JPWO2017195303A1 - Lighting device - Google Patents

Abstract

  The light conversion unit (100) of the illumination device (10) includes a first light conversion member (110) and a second light conversion member (120) that generate heat when converting the optical characteristics of the primary light, and a first light conversion unit (100). A heat transfer suppressing member (130) having a thermal conductivity lower than that of at least one of the light converting member (110) and the second light converting member (120). The first light conversion member (110) is disposed away from the second light conversion member (120). The heat transfer suppression member (130) is disposed at least in part between the first light conversion member (110) and the second light conversion member (120), and the first light conversion member (110) and the second light conversion member. Heat transfer from one of the members (120) to the other of the first light conversion member (110) and the second light conversion member (120) is suppressed.

Description

  The present invention relates to a lighting device.

  The excitation light emitted from the small solid light source is guided by an optical fiber, and the wavelength of the excitation light is converted by a wavelength conversion member disposed at the tip of the optical fiber to emit illumination light having a desired irradiation pattern or color, for example. Lighting devices have been proposed.

  For example, Patent Document 1 discloses a light source that emits excitation light, a light guide member that guides excitation light emitted from the light source, and receives excitation light and absorbs at least part of the received excitation light. A light-emitting device including a wavelength conversion member that emits light having a wavelength different from the wavelength of excitation light (wavelength-converted light) as illumination light is disclosed.

JP 2008-270229 A

  In the wavelength conversion member of Patent Document 1, a plurality of wavelength conversion layers are stacked on each other, each of the wavelength conversion layers converts the wavelength of the excitation light to emit wavelength conversion light, and the plurality of wavelength conversion lights are illumination light. Used as Therefore, illumination light having a good color (color rendering) is realized.

  However, when the first wavelength conversion layer of the plurality of wavelength conversion layers performs wavelength conversion, heat is generated from the first wavelength conversion layer due to conversion loss. This heat is transferred from the first wavelength conversion layer to the second wavelength conversion layer among the plurality of wavelength conversion layers by the laminated structure of the plurality of wavelength conversion layers. Therefore, the wavelength conversion member performs wavelength conversion under a temperature increase due to the total calorific value obtained by adding the calorific values of the wavelength conversion layers.

  The phosphor disclosed as the wavelength conversion member generally has a temperature quenching characteristic that the wavelength conversion efficiency decreases as the temperature of the phosphor increases. The wavelength conversion member emits light when the temperature rises due to the amount of heat generated by the wavelength conversion layer alone and then rises to a higher temperature. Therefore, the wavelength conversion efficiency decreases due to the temperature extinction characteristic, and the brightness of the illumination light decreases.

  For example, it is assumed that the light-emitting device is mounted on an endoscope that requires bright illumination light, and at this time, the wavelength conversion member is disposed at the distal end portion of the endoscope insertion portion. Due to the wavelength conversion layer, the temperature rises locally at the insertion portion. Then, it is conceivable that the wavelength conversion efficiency is lowered due to the temperature quenching characteristic, the brightness of the illumination light is lowered, and the requirement required by the endoscope is not satisfied.

  The present invention has been made in view of these circumstances, and an object thereof is to provide an illuminating device capable of realizing bright illumination light while suppressing concentration of heat.

  One embodiment of the present invention is a lighting device including a light conversion unit that converts an optical characteristic of primary light and emits illumination light, and the light conversion unit absorbs and absorbs part of the primary light. A first light conversion member and a second light conversion member that convert the optical characteristics of the primary light and generate heat when converting the optical characteristics, the first light conversion member, and the second light conversion member. A heat transfer suppression member having a thermal conductivity lower than at least one of the thermal conductivity, and the first light conversion member is disposed apart from the second light conversion member, and the heat transfer The suppression member is disposed at least in part between the first light conversion member and the second light conversion member, and the first light conversion from one of the first light conversion member and the second light conversion member. The transmission of the heat to the other of the member and the second light conversion member is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the illuminating device which can suppress the concentration of heat and can implement | achieve bright illumination light can be provided.

FIG. 1 is a schematic view of an endoscope system having the illumination device according to the first embodiment. FIG. 2 is a diagram schematically illustrating a light conversion unit of the lighting apparatus according to the first embodiment. FIG. 3 is a diagram illustrating an excitation spectrum and an emission spectrum of the first and second light conversion members in the illumination device of the first embodiment. FIG. 4 is a diagram showing the relationship between the temperature and the emission intensity maintenance rate in the first and second light conversion members. FIG. 5 is a diagram schematically showing the primary light, the first converted light, and the second converted light inside the holder in the light conversion unit. FIG. 6 is a diagram illustrating an example of light distribution characteristics of illumination light (first converted light and second converted light) emitted from the light conversion unit. FIG. 7 is a diagram illustrating an example of heat transferred inside the holder. FIG. 8 is a diagram schematically illustrating a light conversion unit in Modification 1 of the first embodiment. FIG. 9 is a diagram schematically illustrating a light conversion unit in Modification 2 of the first embodiment. FIG. 10 is a diagram schematically illustrating a light conversion unit in Modification 3 of the first embodiment. FIG. 11 is a diagram schematically illustrating a light conversion unit in Modification 4 of the first embodiment. FIG. 12 is a diagram schematically illustrating a light conversion unit in Modification 5 of the first embodiment. FIG. 13 is a diagram schematically illustrating the primary light, the first converted light, and the second converted light inside the holder in the light conversion unit of the lighting apparatus according to the second embodiment. FIG. 14 is a diagram schematically illustrating the primary light and the first converted light inside the holder according to Modification 1 of the second embodiment. FIG. 15 is a diagram schematically illustrating a light conversion unit in Modification 2 of the second embodiment. FIG. 16 is a diagram schematically illustrating a light conversion unit of the illumination device according to the third embodiment. FIG. 17 is a schematic view of an endoscope system having the illumination device according to the fourth embodiment.

[First Embodiment]
FIG. 1 is a schematic diagram of an endoscope system 1 having an illumination device 10 according to the first embodiment. The endoscope system 1 includes an illuminating device 10 that irradiates the observation object S with illumination light, and an input unit 30 that is a user interface for setting the illumination light amount of the illumination light, for example. The endoscope system 1 includes an image acquisition device 50 that acquires an image of the observed object S by reflected light from the observed object S, and an image display unit 70 that displays an image of the observed object S. Although the illuminating device 10 of this embodiment is an illuminating device for endoscopes used for the endoscope system 1, it is not necessarily limited to this, It is an illuminating device used for apparatuses other than an endoscope. Also good.

  The endoscope system 1 also includes an endoscope 2, a main body 40, and a connection unit 60 that removably connects the endoscope 2 and the main body 40. The endoscope 2 includes, for example, an insertion portion 20 whose distal end is inserted into a lumen, a gripping portion 21 provided continuously with a proximal end portion of the insertion portion 20, and a universal cord 23 extending from the gripping portion 21. Have. The connection part 60 connects the end part of the universal cord 23 and the main body part 40 detachably. The illumination device 10 and the image acquisition device 50 are disposed across the connection unit 60 and the main body unit 40 from the endoscope 2. The input unit 30 is disposed in the main body unit 40. The image display unit 70 is separate from the insertion unit 20, the main body unit 40, and the connection unit 60.

  The illumination device 10 includes a primary light source 11 that emits primary light, a light source control circuit 12 that controls the primary light source 11, an optical fiber 13 that guides primary light emitted from the primary light source 11, The optical conversion unit 100 converts the optical characteristics of the primary light guided by the optical fiber 13 and emits the converted light as illumination light. The light conversion unit 100 emits illumination light from the light conversion unit 100 to a front irradiation region, and irradiates the observation object S with illumination light.

  The input unit 30 has a user interface for setting the power supply operation (ON / OFF) of the illumination device 10 and the amount of illumination light emitted from the illumination device 10. The input unit 30 may input an instruction regarding control of the endoscope system 1 to each component. An instruction from the user is input to the input unit 30 from an input device such as a keyboard and a mouse (not shown).

  The image acquisition device 50 includes an imaging unit 51 and an image processing circuit 52. The imaging unit 51 includes an imaging device that is, for example, a CCD imager, and is disposed at the distal end of the insertion unit 20 inside the insertion unit 20. The imaging unit 51 reflects the illumination light emitted from the illumination device 10 by the observation object S and converts an optical image obtained from the reflected light into an electrical signal. The image processing circuit 52 is electrically connected to the imaging unit 51 and is disposed in the main body unit 40. The image processing circuit 52 generates an image signal of the observation object S based on the electrical signal output from the imaging unit 51.

  The image display unit 70 is connected to the image processing circuit 52 of the image acquisition device 50. The image display unit 70 is a general display device such as a liquid crystal display, and displays an image of the observation object S based on the image signal generated by the image processing circuit 52.

A detailed configuration of the illumination device 10 will be described.
The illumination device 10 includes the primary light source 11, the light source control circuit 12, the optical fiber 13, and the light conversion unit 100 as described above. The primary light source 11 and the light source control circuit 12 are disposed in the main body 40. The optical fiber 13 is disposed across the main body portion 40 from the endoscope 2 via the connection portion 60. The light conversion unit 100 is disposed at the tip of the insertion unit 20 inside the insertion unit 20.

  The primary light source 11 is optically connected to the light conversion unit 100 via an optical fiber 13 that guides the primary light emitted from the primary light source 11 to the light conversion unit 100. The primary light source 11 includes, for example, a laser diode (hereinafter, referred to as a blue LD 14) that emits blue laser light having an emission wavelength peak of 445 nm, and a light source driving unit 15 for driving the blue LD 14. The blue LD 14 is a first laser light source that emits a first laser beam that is primary light. The primary light in the present embodiment is defined as blue laser light having an emission wavelength peak of 445 nm.

  The light source control circuit 12 is connected to the primary light source 11. The light source control circuit 12 is connected to the input unit 30 and the image acquisition device 50 (image processing circuit 52). The light source control circuit 12 receives light amount control information for illumination light output from the input unit 30 or dimming control information output from the image acquisition device 50. Based on these control information, the light source control circuit 12 transmits a control signal for driving the blue LD 14 at a predetermined drive current and drive interval to the light source drive unit 15. The light source driving unit 15 drives the blue LD 14 based on the control signal.

  The optical fiber 13 is a light guide member that guides the primary light emitted from the primary light source 11 to the light conversion unit 100. The incident end of the optical fiber 13 is connected to the primary light source 11. The exit end of the optical fiber 13 (hereinafter referred to as the optical fiber exit end 16) is connected to the light conversion unit 100. The optical fiber 13 in the present embodiment is, for example, a multimode optical fiber having a core diameter of 50 μm and a numerical aperture FNA = 0.2. The optical fiber 13 includes a core 13a (see FIG. 2), a clad 13b (see FIG. 2) that covers the core 13a, and a jacket (not shown) that covers the clad 13b. The optical fiber exit end 16 side of the optical fiber 13 in a state where the jacket is peeled and the outer peripheral surface of the clad 13b is exposed is inserted into the hollow portion 161 of the first holder 160 described later. Since the primary light is confined in the core 13a, the refractive index of the core 13a is higher than the refractive index of the cladding 13b. For the jacket, for example, a resin such as nylon, acrylic, polyimide, or ETFE is used to improve the mechanical strength of the optical fiber 13 such as tensile resistance and bending resistance.

  The light conversion unit 100 is disposed on the optical fiber output end 16 side. The light conversion unit 100 receives primary light emitted from the optical fiber emitting end 16. Then, the light conversion unit 100 converts a part of the received primary light into first and second converted light having optical characteristics (for example, wavelength characteristics) different from the primary light, and converts the first and second converted lights to Output as illumination light. Therefore, the light conversion unit 100 emits light composed of two light components, that is, a first light component (first converted light) and a second light component (second converted light) as illumination light. The light distribution characteristics of the first and second converted lights emitted from the light conversion unit 100 do not vary depending on the amount of incident primary light, and are constant.

  FIG. 2 is a diagram schematically showing the light conversion unit 100. The light conversion unit 100 includes a first light conversion member 110, a second light conversion member 120, a first heat transfer suppression member 130, a first transparent member 140, a second transparent member 150, and a first holder 160. And a reflection member 170.

  Here, the central axis of the primary light emitted from the optical fiber emitting end 16 is referred to as an optical axis C. The first light conversion member 110, the second light conversion member 120, the first heat transfer suppression member 130, the first transparent member 140, the second transparent member 150, the first holder 160, and the reflection member 170 are The optical axis C is arranged in a rotationally symmetric manner.

  The first and second light conversion members 110 and 120 absorb a part of the primary light and convert the optical characteristics of the absorbed primary light. The first and second light conversion members 110 and 120 emit first and second converted light having optical characteristics different from the optical characteristics of the primary light. For example, the first light conversion member 110 absorbs a part of the primary light and converts the primary light into first converted light having a wavelength range different from that of the primary light. The second light conversion member 120 absorbs the other part of the primary light and converts the primary light into second converted light having a wavelength range different from that of the primary light. Accordingly, the first and second light conversion members 110 and 120 are wavelength conversion members that convert the wavelength of the primary light into first and second wavelength converted light that is first and second converted light having a wavelength range different from that of the primary light. It is. Although details will be described later, the wavelength range of the first converted light is different from the wavelength range of the second converted light. In the present embodiment, the first and second converted lights are emitted from the light conversion unit 100 to the front irradiation area and used as illumination light irradiated to the object S to be observed. Although details will be described later, the first and second light conversion members 110 and 120 generate predetermined heat according to the conversion loss when converting the optical characteristics.

The first and second light conversion members 110 and 120 have the following optical properties and thermal properties.
As shown in FIG. 3, the first light conversion member 110 in the present embodiment absorbs and absorbs part of the primary light (blue laser light) emitted from the primary light source 11 (blue LD 14). The wavelength of the next light is converted into first converted light (first wavelength converted light, yellow fluorescence). The first wavelength converted light is fluorescence having a light emission wavelength peak at 550 nm on the longer wavelength side (yellow region) than the primary light, and has a broadband spectral characteristic with a half-value width of 130 nm. Specifically, the first light conversion member 110 has a phosphor (not shown) represented by a composition of Y ₃ Al ₅ O ₁₂ : Ce (hereinafter referred to as YAG). The first light conversion member 110 is a polycrystallized YAG ceramic. YAG ceramics has a property of hardly diffusing transmitted excitation light and has a high thermal conductivity of about 12 W / mK. In addition to the YAG ceramics, the first light conversion member 110 may be made of a phosphor such as YAG single crystal, ceramics such as LAG: Ce and TAG: Ce.

  As shown in FIG. 3, the second light conversion member 120 in the present embodiment absorbs and absorbs another part of the primary light (blue laser light) emitted from the primary light source 11 (blue LD 14). The converted primary light is converted into a second converted light (second wavelength converted light, green fluorescence). The second wavelength-converted light is fluorescence having a light emission wavelength peak at 540 nm on the longer wavelength side (green region) than the primary light, and has a broadband spectral characteristic with a half-value width of 65 nm. The second light conversion member 120 has a powder phosphor (not shown) and a glass-sealed green phosphor (not shown) including a sealing member that seals the powder phosphor. Specifically, Eu-activated oxynitride phosphor is used as the powder phosphor. The sealing member is, for example, a transparent resin that is an inorganic material such as glass. The second light conversion member 120 has an optical characteristic that transmits at least part of the first converted light.

  The first and second light conversion members 110 and 120 have predetermined efficiency characteristics as internal quantum efficiency (conversion efficiency) for converting the amount of absorbed primary light into the amount of first and second wavelength converted light. Specifically, the first light conversion member 110 (YAG) and the second light conversion member 120 (Eu-activated oxynitride phosphor) have an internal quantum efficiency of approximately 80%. Therefore, when the first and second light conversion members 110 and 120 perform wavelength conversion, the light amount corresponding to approximately 80% is wavelength-converted with respect to the light amount of the primary light absorbed by the first and second light conversion members 110 and 120. The amount of light corresponding to approximately 20% is lost. The amount of light that is lost is converted into heat, and the first and second light conversion members 110 and 120 generate heat. Thus, when the first and second light conversion members 110 and 120 perform wavelength conversion, a conversion loss corresponding to the internal quantum efficiency occurs, and heat corresponding to the conversion loss is generated by the first and second light conversion members 110 and 120. Will occur.

  The first and second light conversion members 110 and 120, which are wavelength conversion members, have a temperature quenching characteristic in which the internal quantum efficiency (conversion efficiency (emission intensity maintenance rate)) decreases due to a temperature increase caused by heat generation at light emission points p1 and p2 described later. Have Specifically, as shown in FIG. 4, the emission intensity maintenance rate of the emission points p1 and p2 of the first and second light conversion members 110 and 120 arranged under the condition of room temperature 25 ° C. is defined as 100%. When the emission point p1 is 150 ° C., the emission intensity maintenance rate is about 80%, and when the emission point p1 is 300 ° C., the emission intensity maintenance rate is about 50%. When the emission point p2 is 150 ° C., the emission intensity maintenance rate is approximately 90%, and when the emission point p2 is 300 ° C., the emission intensity maintenance rate is approximately 75%.

  Therefore, the first and second light conversion members 110 and 120 have a high internal quantum efficiency and have a small amount of heat generated due to conversion loss, or the internal quantum efficiency does not easily decrease as the temperature rises due to heat generation (temperature quenching). It is preferable that it is a member.

  In the internal quantum efficiency of the present embodiment, the ratio of the internal quantum efficiency is preferably 50% or more higher than the ratio of conversion loss. In this case, for example, the first and second light conversion members 110 and 120 include TAG (yellow fluorescence), silicate (green) in addition to YAG (yellow fluorescence) and Eu-activated oxynitride phosphor (green fluorescence). -Orange), α-sialon (yellow fluorescence), β-sialon (green fluorescence), LuAG (green fluorescence), CASN (red fluorescence), and other inorganic fluorescent materials can be used.

  The heat generated from the first and second light conversion members 110 and 120 is efficiently transferred to the first holder 160 by increasing the contact area between the first and second light conversion members 110 and 120 and the first holder 160 described later. Communicated. Accordingly, the first and second light conversion members 110 and 120 having an internal quantum efficiency of about 20% may be used.

  In the temperature quenching characteristics of the present embodiment, for example, the first and second light conversion members 110 and 120 are preferably members having light emission points p1 and p2 of around 150 ° C. and a light emission intensity maintenance rate of approximately 50% or more. In this case, the first and second light conversion members 110 and 120 are oxynitride-based, nitride-based phosphors such as α-sialon (yellow fluorescence), β-sialon (green fluorescence), CASN (red fluorescence), An oxide phosphor such as YAG can be used.

  In this embodiment, it is not necessary to be limited to the combination of the first light conversion member 110 that emits yellow fluorescence and the second light conversion member 120 that emits green fluorescence. For example, the first and second light conversion members 110 and 120 that emit fluorescence of other colors such as green fluorescence and red fluorescence may be combined with each other according to the application for observing the object S to be observed. Further, for example, a secondary absorption structure is arranged in which the first light conversion member 110 emits first fluorescence such as green, and the second light conversion member 120 absorbs the first fluorescence and emits second fluorescence such as red. Also good.

  The thermal conductivity of the first light conversion member 110 (YAG) is, for example, 12 W / m · K, and the thermal conductivity of the second light conversion member 120 (glass-sealed green phosphor) is, for example, 1 W / m · K. Thus, the thermal conductivity of the first light conversion member is higher than the thermal conductivity of the second light conversion member. The thermal conductivity of the first and second light conversion members 110 and 120 is higher than the thermal conductivity of the first heat transfer suppressing member 130.

  The first and second light conversion members 110 and 120 are preferably materials having characteristics that do not deteriorate with respect to the heat generation amount of the first and second light conversion members 110 and 120 themselves. For example, the first and second light conversion members 110 and 120 use, in addition to YAG and glass-sealed green phosphor, an inorganic material having high heat resistance such as single crystal phosphor and ceramic-sealed phosphor. Is preferred.

  For example, considering the heat resistance of the phosphor itself and the heat dissipation to the first holder 160, the second light conversion member 120, which is a green phosphor, may be, for example, a LuAG single crystal. The thermal conductivity of the LuAG single crystal is, for example, 12 W / m · K.

  In the present embodiment, the first light conversion member 110 is more primary light than the second light conversion member 120 in consideration of the primary light absorption rate and the internal quantum efficiency of the first and second light conversion members 110 and 120. And the thickness of the first and second light conversion members 110 and 120 and the second light conversion member 120 so that the first light conversion member 110 wavelength-converts more light than the second light conversion member 120. The concentration of the powder phosphor with respect to the sealing member is adjusted. Therefore, the heat generation amount of the first light conversion member 110 generated by light conversion is larger than the heat generation amount of the second light conversion member 120 generated by light conversion.

  The first and second light conversion members 110 and 120 have a columnar shape, for example, a columnar shape. The diameter of the second light conversion member 120 is larger than the diameter of the first light conversion member 110.

  For example, the diameter of the first light conversion member 110 is 1.0 mm, and the thickness of the first light conversion member 110 is 0.25 mm. As shown in FIG. 2, the first light conversion member 110 includes a circular incident surface 111 on which primary light emitted from the optical fiber emitting end 16 is incident, a circular emission surface 112 facing the incident surface 111, And a side surface 113 that is an outer peripheral surface between the incident surface 111 and the output surface 112. The primary light irradiation area on the incident surface 111 is smaller than the incident surface 111.

  For example, the diameter of the second light conversion member 120 is 1.5 mm, and the thickness of the second light conversion member 120 is 0.25 mm. As shown in FIG. 2, the second light conversion member 120 includes a circular incident surface 121 disposed away from the emission surface 112 of the first light conversion member 110, and a circular emission surface 122 facing the incident surface 121. And a side surface 123 that is an outer peripheral surface between the incident surface 121 and the output surface 122.

  In the direction of the optical axis C, the first light conversion member 110 is disposed away from the second light conversion member 120. The central axis of the first light conversion member 110 is arranged on the same straight line as the central axis of the second light conversion member 120.

As shown in FIG. 2, the first heat transfer suppression member 130 is disposed at least at a part between the first light conversion member 110 and the second light conversion member 120. For example, the first heat transfer suppression member 130 is disposed between the plane on which the incident surface 111 is disposed and the plane on which the incident surface 121 is disposed in the optical axis C direction. In addition, the 1st heat transfer suppression member 130 should just be arrange | positioned in the optical axis C direction between the plane where the output surface 112 is arrange | positioned, and the plane where the entrance plane 121 is arrange | positioned. Thus, the first heat transfer suppression member 130 is interposed between the first light conversion member 110 and the second light conversion member 120 in the direction of the optical axis C, and a part of the first light conversion member 110 (exit surface). 112) and a part of the second light conversion member 120 (incident surface 121). The first heat transfer suppression member 130 is thermally connected to the first light conversion member 110 (the emission surface 112 and the side surface 113) and the second light conversion member 120 (the incident surface 121). The first heat transfer suppression member 130 is also disposed on the side of the side surface 113 of the first light conversion member 110 and is in contact with the side surface 113.
The first heat transfer suppression member 130 suppresses heat transfer from one of the first light conversion member 110 and the second light conversion member 120 to the other of the first light conversion member 110 and the second light conversion member 120. . Emphasizing that the first heat transfer suppression member 130 enhances the heat insulating action between the first and second light conversion members 110 and 120, the first heat transfer suppression member 130 includes the first and second light conversion members 110 and 120. The thermal conductivity is lower than the thermal conductivity of at least one of the above. For example, it is assumed that the thermal conductivity of the first heat transfer suppression member 130 is lower than the thermal conductivity (12 W / m · K, 1 W / m · K) of the first and second light conversion members 110 and 120. In this case, for example, the first heat transfer suppressing member 130 includes a transparent silicone resin having a thermal conductivity of 0.2 W / m · K.

  The first heat transfer suppressing member 130 has an optical characteristic that transmits at least part of the primary light (blue laser light) and the first and second converted lights.

  When the thermal conductivity of the first heat transfer suppression member 130 is lower than only the thermal conductivity (12 W / m · K) of the first light conversion member 110, the first heat transfer suppression member 130 is the first heat transfer suppression member 130. In order to improve the heat resistance of 130 itself, a glass having a high transmittance may be used instead of the silicone resin. The thermal conductivity of this glass is, for example, 1 W / m · K.

  The first heat transfer suppressing member 130 is filled with air through which the primary light and the first and second wavelength converted light pass, and has a gap formed between the first and second light converting members 110 and 120. May be. The thermal conductivity of the first heat transfer suppression member 130 formed by this air is, for example, 0.03 W / m · K.

  The thickness of the first heat transfer suppression member 130 on the optical axis C is thinner than the thickness (0.25 mm, 0.25 mm) of each of the first and second light conversion members 110 and 120 on the optical axis C. In other words, the thickness of the first heat transfer suppression member 130 between the plane on which the exit surface 112 is disposed and the plane on which the entrance surface 121 is disposed is the thickness of each of the first and second light conversion members 110 and 120. Thinner than that. On the optical axis C, the thickness of the first heat transfer suppressing member 130 is, for example, 0.1 mm.

  Here, the thermal resistance value which is the thermal characteristic of the 1st, 2nd light conversion members 110 and 120 and the 1st heat transfer suppression member 130 in this embodiment is demonstrated below.

  The thermal resistance value is a numerical value representing the difficulty of heat transmission in the member, and the larger the numerical value of the thermal resistance value, the more difficult the heat is transmitted.

  Here, when the thermal resistance value is HR, the thickness of the member on the optical axis C is T, and the thermal conductivity is C, the following equation (1) is established.

HR = T / C (1)
HR: [(m ² · K) / W)], T: [m], C: [W / (m · K)].

  The thermal resistance values HR1, HR2, and HR3 of the first and second light conversion members 110 and 120 and the first heat transfer suppression member 130 on the optical axis C in the present embodiment are as follows.

HR1 = 0.25 × 10 ⁻³ [m] / 12 [W / (m · K)] = 2.1 × 10 ⁻⁵ [(m ² · K) / W)]
HR2 = 0.25 × 10 ⁻³ [m] / 1 [W / (m · K)] = 2.5 × 10 ⁻⁴ [(m ² · K) / W)]
HR3 = 0.1 × 10 ⁻³ [m] /0.2 [W / (m · K)] = 5.0 × 10 ⁻⁴ [(m ² · K) / W)]
The thickness T3 of the first heat transfer suppression member 130 on the optical axis C is thinner than the thicknesses T1 and T2 of the first and second light conversion members 110 and 120, but the first heat transfer suppression member 130 on the optical axis C. The thermal conductivity C3 is different from the thermal conductivities C1 and C2 of the first and second light conversion members 110 and 120. For this reason, the thermal resistance value HR3 on the optical axis C is larger than the thermal resistance values HR1 and HR2 on the optical axis C.

  The thermal resistance value HR3 is set in consideration of the combination of the thermal conductivity C3 and the thickness T3 so that the thermal resistance value HR3 is larger than the thermal resistance values HR1 and HR2. The thermal resistance value HR3 is preferably twice or more than the thermal resistance values HR1 and HR2. Accordingly, the first heat transfer suppressing member 130 effectively transmits heat generated from one of the first and second light conversion members 110 and 120 to the other of the first and second light conversion members 110 and 120. Can be suppressed.

  For example, the first and second transparent members 140 and 150 include glass or silicone resin (thermal conductivity: 0.2 W / m · K) having high transmittance. The first and second transparent members 140 and 150 have a property of transmitting at least part of the primary light (blue laser light) and the first and second converted lights. Instead of the first and second transparent members 140 and 150, a transparent region such as a gap may be disposed.

  As shown in FIG. 2, the first transparent member 140 has a truncated cone shape. The first transparent member 140 includes a small circular incident surface 141 on which primary light emitted from the optical fiber output end 16 is incident, a large circular output surface 142 facing the incident surface 141, and the incident surface 141 and the output surface. 142 and a side surface 143 which is an outer peripheral surface between the first and second surfaces. The incident surface 141 is the same size as the optical fiber output end 16 or is larger than the optical fiber output end 16. The incident surface 141 is optically connected to the optical fiber output end 16. The exit surface 142 is in contact with the entrance surface 111. The entire side surface 143 is in contact with the tapered surface 165 that is the inner peripheral surface of the first holder 160.

  As shown in FIG. 2, the second transparent member 150 has a substantially truncated cone shape. The second transparent member 150 includes a concave contact surface 151 on which the second light conversion member 120 is disposed, a large circular emission surface 152 facing the contact surface 151, and an outer periphery between the contact surface 151 and the emission surface 152. And a side surface 153 which is a surface. On the contact surface 151, the second transparent member 150 is in contact with the emission surface 122 and the side surface 123 of the second light conversion member. The entire side surface 153 is in contact with the tapered surface 165 that is the inner peripheral surface of the first holder 160.

  For example, the first holder 160 includes metal brass having a thermal conductivity higher than that of the first and second light conversion members 110 and 120. The thermal conductivity of the first holder 160 is 120 W / m · K. For example, the thermal conductivity (12 W / m · K) of the first light conversion member 110 (YAG) and the second light conversion member 120 ( It is higher than the thermal conductivity (1 W / m · K) of the glass-sealed green phosphor. Since the first holder 160 has no optical restriction such as transmittance, the degree of freedom in selecting the first holder 160 is high. For example, the first holder 160 may be a member having a high thermal conductivity such as a metal such as aluminum or copper or a metal compound such as aluminum nitride. In addition, the 1st holder 160 should just have thermal conductivity higher than the thermal conductivity of the 1st heat-transfer suppression member 130. FIG. The volume of the first holder 160 is larger than the volume of each of the first and second light conversion members 110 and 120, and the surface area of the first holder 160 is larger than the surface area of each of the first and second light conversion members 110 and 120.

  The first holder 160 includes an optical fiber emitting end 16, a first light conversion member 110, a second light conversion member 120, a first heat transfer suppressing member 130, a first transparent member 140, and a second transparent member 150. And hold inside. The first holder 160 has, for example, a cylindrical shape. The first holder 160 includes a cylindrical hollow portion 161 in which the optical fiber output end 16 is disposed, and a cone whose diameter is expanded from the optical fiber output end 16 in the primary light output direction (axial direction). And a trapezoidal hollow portion 162. The hollow portions 161 and 162 continuously extend in the axial direction around the optical axis C, and penetrate the inside of the first holder 160.

  The hollow portion 162 is an opening portion on which the incident surface 141 side of the first transparent member 140 is disposed, and a holder incident portion 163 where primary light is incident and an opening portion on which the emission surface 152 side of the second transparent member 150 is disposed. And a holder emitting part 164 for emitting illumination light. The hollow portion 162 is a through-hole portion penetrating from the holder incident portion 163 to the holder emitting portion 164, and has a tapered shape that increases in diameter from the holder incident portion 163 to the holder emitting portion 164. In other words, the inner peripheral surface forming the hollow portion 162 forms a tapered surface 165. The primary light enters the holder incident portion 163 from the optical fiber exit end 16. The holder emitting unit 164 emits the first and second converted light as illumination light.

  In the hollow portion 162, the first transparent member 140, the first light conversion member 110, the first heat transfer suppression member 130, the second light conversion member 120, in order from the optical fiber exit end 16 side on the optical axis C, The second transparent member 150 is disposed and held. The emission surface 152 of the second transparent member 150 and the end surface of the holder emission part 164 are disposed on substantially the same plane. The exit surface 122 of the second light conversion member 120 is present inside the end surface of the holder exit portion 164.

  At least a part of the first light conversion member 110 and the second light conversion member 120 is disposed on the optical axis C that is the central axis of the primary light incident on the holder incident portion 163. The first light conversion member 110 is disposed between the holder incident portion 163 and the second light conversion member 120. At least a part of the first heat transfer suppression member 130 is disposed between the first light conversion member 110 and the second light conversion member 120 and in a region including the optical axis C. The entire side surface 133 of the first heat transfer suppression member 130 contacts the tapered surface 165 and is thermally connected to the tapered surface 165. The first heat transfer suppressing member 130 contacts the tapered surface 165 from the edge of the incident surface 111 to the edge of the incident surface 121.

  The central axis of the first holder 160 is coaxial with the optical axis C of the primary light emitted from the optical fiber emitting end 16. The first light conversion member 110, the second light conversion member 120, the first heat transfer suppression member 130, the first transparent member 140, and the second transparent member 150 are in the hollow portion 162 with respect to the central axis of the first holder 160. Arranged symmetrically (rotationally symmetric). In the present embodiment, only the edge of the incident surface 111 and the edge of the incident surface 121 are in contact with the tapered surface 165 and the reflecting member 170 over the entire circumference, and the side surface 113 of the first light conversion member 110 and the second light. The side surface 123 of the conversion member 120 is disposed away from the tapered surface 165. As described above, some of the first and second light conversion members 110 and 120 are thermally connected to the first holder 160 and the reflection member 170.

  The taper angle of the first holder 160 is defined by an inclination angle formed by the taper surface 165 that is the inner peripheral surface of the truncated cone and the central axis of the first holder 160. In order to efficiently extract the omnidirectional first and second converted lights from the light conversion unit 100, the taper angle is preferably in the vicinity of 10 ° to 60 °. Specifically, the light conversion unit 100 (first holder 160) in the present embodiment has a taper angle of 25 °, an incident diameter of 0.4 mm, and an output diameter of 2.6 mm.

  A reflective member 170 is formed on the tapered surface 165 of the first holder 160. The reflecting member 170 preferably has a high reflectance and a high thermal conductivity. The reflecting member 170 in the present embodiment is a metal reflecting film (reflecting mirror) in which a tapered surface 165 is thinly plated with a metal such as silver or aluminum. For example, the thermal conductivity of silver is 420 W / m · K, and the thermal conductivity of aluminum is 240 W / m · K. When the primary light, the first converted light, and the second converted light are incident on the reflective member 170, the reflective member 170 reflects them regularly or diffusely. The reflection member 170 changes the light distribution of each of the first and second converted lights by reflection so that the light distribution angles of the first and second converted lights emitted from the holder emitting portion 164 are equal to each other.

  The primary light emitted from the optical fiber emitting end 16 is irradiated most strongly on the optical axis C. The position at which the primary light is most strongly irradiated on the first light conversion member 110 is the position of the intersection between the incident surface 111 of the first light conversion member 110 and the optical axis C where the primary light is irradiated. It is also a position where the intensity of the first converted light that has been partially wavelength-converted by absorbing a part of the primary light is the strongest. This intersection point is defined as a substantial light emission point p1 of the first light conversion member 110. Similarly, the position where the primary light is most strongly irradiated on the second light conversion member 120 is the position of the intersection between the incident surface 121 of the second light conversion member 120 and the optical axis C where the primary light is irradiated. It is also a position where the intensity of the second converted light is the strongest. Therefore, this intersection is defined as a substantial light emitting point p2 of the second light conversion member 120.

(Operation of illumination light when primary light is incident)
With reference to FIGS. 5 and 6, the operation of generating illumination light in the light conversion unit 100 will be described. The primary light is guided by the optical fiber 13 and emitted from the optical fiber emitting end 16 to the light conversion unit 100. The light distribution of the primary light emitted from the optical fiber output end 16 is narrow, and the light distribution half-value angle is about 15 °. The intensity of the primary light is highest on the optical axis C.

  As shown in FIG. 5, the primary light emitted to the light conversion unit 100 passes through the first transparent member 140 and enters the incident surface 111 of the first light conversion member 110 (YAG). A part of the incident primary light is absorbed by the first light conversion member 110 and the other part is transmitted through the first light conversion member 110. The absorbed primary light is wavelength-converted to first converted light (yellow fluorescent light), is generated from an area including the substantial light emitting point p1 of the first light converting member 110, and isotropically emitted.

  As shown in FIG. 5, a part of the first converted light emitted from the first light conversion member 110 to at least one of the side and the front is a first heat transfer suppressing member 130 and a second light conversion member 120. And the second transparent member 150, and the tapered surface 165 of the first holder 160 is irradiated. The first converted light is reflected by the reflecting member 170 on the tapered surface 165, and the traveling direction of the first converted light changes. Then, the first converted light is emitted forward from the emission surface 152 (holder emission part 164) of the second transparent member 150 without re-entering the first light conversion member 110. Although not shown, a part of the first converted light emitted forward does not proceed to the reflecting member 170 but is directly emitted forward from the emission surface 152 (holder emission part 164). That is, a part of the first converted light is emitted without the traveling direction of the first converted light being changed by the reflecting member 170. Further, a part of the first converted light emitted from the substantial light emitting point p1 of the first light converting member 110 to the rear (on the optical fiber emitting end 16 side) proceeds to the reflecting member 170 on the tapered surface 165. Although not shown, the first converted light is reflected by the reflecting member 170, and the traveling direction of the first converted light changes forward. And this 1st conversion light permeate | transmits the 1st light conversion member 110, the 1st heat transfer suppression member 130, the 2nd light conversion member 120, and the 2nd transparent member 150, and the output surface 152 (holder output part 164) Is emitted forward.

  The first converted light is light-distributed and converted by the reflecting member 170, and the component traveling forward from the surroundings increases. Thereby, as shown in FIG. 6, the light distribution with a narrower angle than the isotropic light distribution is realized. At this time, the light distribution half-value angle of the first converted light is 100 ° or less, for example, 72 °.

  On the other hand, the primary light that has not been absorbed by the first light conversion member 110 passes through the first light conversion member 110 and the first heat transfer suppression member 130 as shown in FIG. The incident surface 121 is irradiated. The irradiated primary light is absorbed by the green powder phosphor included in the second light conversion member 120. The absorbed primary light is wavelength-converted to second converted light (green fluorescence), is generated from an area including the substantial light emitting point p2 of the second light conversion member 120, and isotropically emitted. .

  As shown in FIG. 5, a part of the second converted light emitted from the second light conversion member 120 to at least one of the side and the front is transmitted through the second transparent member 150, The taper surface 165 is irradiated. The second converted light is reflected by the reflecting member 170 on the tapered surface 165, and the traveling direction of the second converted light changes. And this 2nd conversion light is radiate | emitted ahead from the output surface 152 (holder radiation | emission part 164), without re-entering into the 1st, 2nd light conversion members 110 and 120. FIG. A portion of the second converted light emitted forward does not travel to the reflecting member 170 but is emitted forward from the direct emission surface 152 (holder emission portion 164). That is, a part of the second converted light is emitted without the traveling direction of the second converted light being changed by the reflecting member 170. Although not shown, a part of the second converted light is emitted backward (from the optical fiber emitting end 16 side) from the substantial light emitting point p2 of the second light converting member 120, and the reflecting member 170 on the tapered surface 165. Proceed to. The second converted light is reflected by the reflecting member 170, and the traveling direction of the second converted light changes forward. And this 2nd conversion light permeate | transmits the 1st light conversion member 110, the 1st heat transfer suppression member 130, the 2nd light conversion member 120, and the 2nd transparent member 150, and the output surface 152 (holder output part 164) Is emitted forward.

  The light emitting point p2 is compared with the light emitting point p1 by the distance between the incident surface 111 and the incident surface 121, in other words, the thickness of the first light conversion member 110 and the first heat transfer suppressing member on the optical axis C. Only the sum of the thickness of 130 is arranged on the emission surface 152 (holder emission part 164) side. However, the light emitting points p <b> 1 and p <b> 2 are arranged at a position that is 2/3 or less of the length of the first holder 160 from the incident surface 141 (holder incident portion 163). Therefore, the second converted light is light-distributed and converted by the reflecting member 170 in the same manner as the first converted light, and a light distribution that is narrower than the isotropic light distribution is realized, and the light distribution angle of the second converted light is realized. Is substantially the same as the light distribution angle of the first converted light. At this time, each of the first and second converted lights is emitted in a state where the light distribution half-value angle of each of the first and second converted lights is 100 ° or less.

  On the optical axis C, the first heat transfer suppression member 130 is thinner than the first and second light conversion members 110 and 120. Therefore, the light emitting point p2 can be disposed close to the light emitting point p1, and the light distribution characteristic of the second converted light can approach the light distribution characteristic of the first converted light. At this time, as shown in FIG. 6, the light distribution half-value angle of the second converted light is 100 ° or less, for example, 76 °. Then, the first and second converted lights having a narrow light distribution are emitted from the holder emitting portion 164 as illumination light.

  Next, heat generated from the light conversion unit 100 and heat transfer will be described with reference to FIG. Here, focusing on the light emitting points p1 and p2, which are the places where the heat is most generated, the transfer of heat generated from the light emitting points p1 and p2 will be described.

  When the primary light absorbed by the first and second light conversion members 110 and 120 is converted into first and second converted light, the first and second light conversion members 110 and 120 generate heat due to the conversion loss. The amount of heat generated is proportional to the amount of primary light incident on the first and second light conversion members 110 and 120.

  Here, the path of heat generated from the first and second light conversion members 110 and 120 and the amount of heat transferred in each path will be described. The amount of heat transferred in each path depends on the thermal conductivity of members arranged around the first and second light conversion members 110 and 120.

  The members disposed around the first light conversion member 110 are, for example, the first heat transfer suppression member 130, the first transparent member 140, the first holder 160, and the reflection member that are thermally connected to the first light conversion member 110. 170. The first heat transfer suppressing member 130 and the first transparent member 140 include a silicone resin having a low thermal conductivity (0.2 W / m · K). The first holder 160 includes brass having a high thermal conductivity (120 W / m · K), and the reflecting member 170 includes silver having a high thermal conductivity (420 W / m · K).

Here, the heat generated from the first light conversion member 110 is transmitted mainly through three paths. These routes are referred to as first, second, and third routes R1, R2, and R3.
In the first path R <b> 1, heat is transferred from the first light conversion member 110 to the second light conversion member 120 via the first heat transfer suppression member 130.
In the second path R <b> 2, heat is transmitted from the first light conversion member 110 to the first holder 160 via the reflection member 170, and is released to the outside from the first holder 160.
In the third path R <b> 3, heat is transmitted from the first light conversion member 110 to the optical fiber 13 through the first transparent member 140 and is released to the outside from the optical fiber 13.
For example, the amount of heat transferred in each path is determined in the order of the second path R2, the first path R1, and the third path R3 in consideration of the thermal conductivity of each member disposed around the first light conversion member 110. Lower. That is, the first heat transfer amount in the first path R1 is smaller than the second heat transfer amount in the second path R2.

  For this reason, the heat generated from the first light conversion member 110 is transmitted to the second path R2 in preference to the first path R1 and the third path R3, and is diffused. Accordingly, the amount of heat transmitted through the second path R2 is greater than the amount of heat transmitted through the first and third paths. For example, it is assumed that the thermal conductivity of the first heat transfer suppressing member 130 is the same as the thermal conductivity of the first transparent member 140. In addition, the thickness (0.1 mm) of the first heat transfer suppressing member 130 on the optical axis C is thinner than the thickness of the first transparent member 140 on the optical axis C. Accordingly, the amount of heat transmitted through the first path R1 is greater than the amount of heat transmitted through the third path R3.

  Further, the members disposed around the second light conversion member 120 are, for example, the first heat transfer suppressing member 130, the second transparent member 150, and the first holder 160 that are thermally connected to the second light conversion member 120. A reflection member 170 is shown. The first heat transfer suppressing member 130 and the second transparent member 150 include a silicone resin having a low thermal conductivity (0.2 W / m · K). The first holder 160 includes brass having a high thermal conductivity (120 W / m · K), and the reflecting member 170 includes silver having a high thermal conductivity (420 W / m · K).

Here, the heat generated from the second light conversion member 120 is transmitted mainly through three paths. These routes are referred to as fourth, fifth, and sixth routes R4, R5, and R6.
In the fourth path R4, heat is transferred from the second light conversion member 120 to the first light conversion member 110 via the first heat transfer suppression member 130.
In the fifth path R <b> 5, heat is transmitted from the second light conversion member 120 to the first holder 160 via the reflecting member 170, and is released to the outside from the first holder 160.
In the sixth path R6, heat is transmitted from the second light conversion member 120 to the second transparent member 150 and is released from the second transparent member 150 to the outside.
For example, the amount of heat transferred in each path is determined in the order of the fifth path R5, the fourth path R4, and the sixth path R6 in consideration of the thermal conductivity of each member disposed around the first light conversion member 110. Lower.

  For this reason, the heat generated from the second light conversion member 120 is transmitted to the fifth path R5 in preference to the fourth path R4 and the sixth path R6 and is diffused. Therefore, the amount of heat transmitted through the fifth path R5 is greater than the amount of heat transmitted through the fourth and sixth paths. For example, it is assumed that the thermal conductivity of the first heat transfer suppressing member 130 is the same as the thermal conductivity of the second transparent member 150. Further, the thickness (0.1 mm) of the first heat transfer suppressing member 130 on the optical axis C is thinner than the thickness of the second transparent member 150 on the optical axis C. Accordingly, the amount of heat transmitted through the fourth path R4 is greater than the amount of heat transmitted through the sixth path R6.

  The first holder 160 is brass, and the volume and surface area of the first holder 160 are larger than those of the first and second light conversion members 110 and 120. Therefore, when heat is continuously generated from the first and second light conversion members 110 and 120, the heat is quickly transferred from the first and second light conversion members 110 and 120 to the first holder 160, and as a result, the first , 2 It is difficult to stay on the light conversion members 110 and 120. The heat is quickly released from the first holder 160 to the outside.

  In the present embodiment, the first heat transfer suppression member 130 is disposed between the first light conversion member 110 and the second light conversion member 120 in the optical axis C direction, and the thermal conductivity of the first heat transfer suppression member 130 is The thermal conductivity of each of the first and second light conversion members 110 and 120 is lower. Therefore, the heat generated from the first and second light conversion members 110 and 120 during light conversion can be suppressed from being concentrated on the first and second light conversion members 110 and 120, and the temperature of the first and second light conversion members 110 and 120 increases. Therefore, it is possible to suppress a decrease in conversion efficiency due to the light and to realize bright illumination light.

  A part of the first and second light conversion members 110 and 120 is thermally connected to the first holder 160 and the reflecting member 170, and the thermal conductivities of the first holder 160 and the reflecting member 170 are the first and second, respectively. It is higher than the thermal conductivity of each of the two light conversion members 110 and 120. Accordingly, heat generated from the first and second light conversion members 110 and 120 during light conversion can be efficiently and preferentially transmitted from the first and second light conversion members 110 and 120 to the first holder 160 and the reflection member 170. That is, the heat generated from the first and second light conversion members 110 and 120 can be dispersed. Even if a large amount of primary light is incident on the first and second light conversion members 110 and 120, most of the heat is emitted from the first and second light conversion members 110 and 120. The conversion members 110 and 120 do not generate much heat and can provide bright illumination light.

  The amount of heat generated by the first light conversion member 110 to which primary light first enters is greater than the amount of heat generated by the second light conversion member 120, but the thermal conductivity of the first light conversion member 110 is that of the second light conversion member 120. Higher than thermal conductivity. Therefore, local heat generated in the light conversion unit 100 is preferentially released from the first light conversion member 110, and a decrease in conversion efficiency of the first light conversion member 110 due to heat can be suppressed. Further, the temperature difference between the first light conversion member 110 and the second light conversion member 120 can be reduced, and illumination light having a stable brightness against heat can be provided.

  For example, the internal quantum efficiencies of the first and second light conversion members 110 and 120 are 50% or more, and when the emission points p1 and p2 of the first and second light conversion members 110 and 120 are 150 ° C., the emission intensity maintenance ratio is It becomes about 50% or more. Therefore, a large amount of primary light can be incident on the light conversion unit 100, and bright illumination light can be provided.

  For example, the first and second light conversion members 110 and 120 are made of an inorganic material having a thermal conductivity higher than that of the resin and having a high heat resistance. As a result, even if a large amount of primary light is incident on the light conversion unit 100 at a high temperature, heat is emitted to the outside due to high thermal conductivity, so that illumination light with stable brightness can be provided.

  The first heat transfer suppression member 130 through which the primary light is transmitted is disposed between the first and second light conversion members 110 and 120. On the optical axis C, the first heat transfer suppression member 130 is the first and second light beams. It is thinner than the conversion members 110 and 120. Therefore, the light emitting point p2 can approach the light emitting point p1, and the light distribution angle of the second converted light can be made substantially the same as the light distribution angle of the first converted light.

  The first and second light conversion members 110 and 120 are disposed inside a first holder 160 having a tapered shape whose diameter increases from the holder incident portion 163 to the holder emitting portion 164. Therefore, the light distribution of the first and second converted light as the illumination light can be narrowed, and the bright illumination light can be irradiated to the observed object S that is away from the holder emitting portion 164 in the optical axis C direction.

  In this embodiment, in addition to the structure including the first light conversion member 110 that emits yellow fluorescence and the second light conversion member 120 that emits green fluorescence, the first light conversion member 110 emits first fluorescence such as green. A structure having a secondary absorption structure that emits and emits second fluorescence such as red light when the second light conversion member 120 absorbs the first fluorescence may be used. The secondary absorption structure is also a non-contact structure in which the first light conversion member 110 is disposed away from the second light conversion member 120. Here, the structure in which the first light conversion member 110 is in contact with the second light conversion member 120 is referred to as a contact structure. In the non-contact structure, the second light conversion member 120 is arranged away from the first light conversion member 110 as compared to the contact structure. Therefore, the amount of green first fluorescence absorbed by the second light conversion member 120 can be reduced, and much green first fluorescence can be used as illumination light.

  The primary light source 11 is not limited to the blue LD 14 and may be an LED. Thereby, the primary light source 11 can be produced at low cost.

  The hollow portion 162 of the first holder 160 may have a columnar shape or a parabolic shape instead of a tapered shape. Thereby, the hollow part 162 can be processed easily and the 1st holder 160 can be produced cheaply.

  The first and second light conversion members 110 and 120 may have a prismatic shape instead of a cylindrical shape. In this case, only the corners of the incident surfaces 111 and 121 arranged in the prism need only be in contact with the tapered surface 165 that is the inner peripheral surface of the first holder 160. Depending on the material of the first and second light conversion members 110 and 120, the prism can be more easily processed than the cylinder by dicing or the like.

  Although not shown, the optical fiber 13 may be omitted, and the emission end of the primary light source 11 may be directly optically connected to the incident surface 141 of the light conversion unit 100, or a spatial optical system having a plurality of lenses may be used. You may arrange | position between the output edge part of the primary light source 11, and the entrance plane 141 of the light conversion unit 100. FIG.

  Each of the first and second light conversion members 110 and 120 is preferably in physical contact with the first holder 160, but is not limited thereto. If heat is transferred from the first light conversion member 110 to the first holder 160, the first light conversion member 110 is close to the first holder 160 even if it is not in physical contact with the first holder 160. May be. In this case, for example, a reflecting member 170, an adhesive layer (not shown), an air layer (not shown), and the like are interposed between the first light conversion member 110 and the first holder 160. The heat generated from the first light conversion member 110 can be transferred from the first light conversion member 110 to the first holder 160 through the reflection member 170, the adhesive layer, the air layer, and the like. Although the first light conversion member 110 and the first holder 160 have been described, the same applies to the second light conversion member 120 and the first holder 160.

  In the present embodiment, the edge of the incident surface 111 of the first light conversion member 110 is in contact with the tapered surface 165 of the first holder 160, and heat is transferred from the first light conversion member 110 to the first holder 160. The edge may be away from the tapered surface 165 if heat is transferred. At this time, the distance between the edge portion and the tapered surface 165 is preferably shorter than the distance between the first light conversion member 110 (exit surface 112) and the second light conversion member 120 (incident surface 121). . Thereby, the amount of heat transferred from the first light conversion member 110 to the first holder 160 can be made larger than the amount of heat transferred from the first light conversion member 110 to the second light conversion member 120. Although the first light conversion member 110 and the first holder 160 have been described, the same applies to the second light conversion member 120 and the first holder 160.

  The first holder 160 may be disposed on the outer peripheral surface of the first holder 160 and may have a fin portion (not shown) that releases heat to the outside. Thereby, the 1st holder 160 can improve heat dissipation efficiency.

  The thermal conductivity of the heat transfer suppressing member may be less than 12 W / m · K. The thermal conductivity of the first holder 160 may be 15 W / m · K or more.

[Modification]
Hereinafter, modifications 1 to 5 of the present embodiment will be described. In each modification, only differences from the present embodiment are mainly described.

  In the first modification shown in FIG. 8, the first light conversion member 110 has, for example, a truncated cone shape, and the entire side surface 113 of the first light conversion member 110 is heated to the tapered surface 165 that is the inner peripheral surface of the first holder 160. Connected. Therefore, the first region where the first light conversion member 110 is thermally connected to the first holder 160 is wider than the second region where the second light conversion member 120 is thermally connected to the first holder 160. . The first region is the entire side surface 113 of the first light conversion member 110, and the second region is the entire periphery of the edge of the incident surface 121 of the second light conversion member 120. In the present modification, the heat generation amount of the first light conversion member 110 is larger than the heat generation amount of the second light conversion member 120.

  Part of the heat generated from the first light conversion member 110 is transmitted to the first holder 160 from the entire side surface 113 of the first light conversion member 110.

  In this modification, the contact area between the first light conversion member 110 and the first holder 160 is larger than that in the first embodiment. Therefore, the amount of heat transferred from the first light conversion member 110 to the first holder 160 can be increased, and the heat dissipation of the first light conversion member 110 that generates a large amount of heat can be improved.

  Further, in this modification, the first heat transfer suppression member 130 has a truncated cone shape, and the entire side surface 133 of the first heat transfer suppression member 130 is thermally applied to the tapered surface 165 that is the inner peripheral surface of the first holder 160. Connected. The emission surface 112 of the first light conversion member 110 is stacked on the first surface 131 of the first heat transfer suppression member 130, and the second surface 132 of the first heat transfer suppression member 130 is stacked on the incident surface 121. The first surface 131 is smaller than the second surface 132. The first surface 131 and the second surface 132 are, for example, circular. For example, primary light and first converted light are incident on the first surface 131, and the second surface 132 emits, for example, primary light and first converted light. The first surface 131 may emit the second converted light, and the second converted light may enter the second surface 132.

  In this modification, the second light conversion member 120 also has a truncated cone shape, for example, and the entire side surface 123 of the second light conversion member 120 is thermally applied to the tapered surface 165 that is the inner peripheral surface of the first holder 160. It may be connected. In this case, the amount of heat transferred from the second light conversion member 120 to the first holder 160 can be increased, and the heat dissipation of the second light conversion member 120 can also be improved.

  9, the light conversion unit 100 is disposed between the first light conversion member 110 and the second light conversion member 120 in the optical axis C direction, and is rotationally symmetrical about the optical axis C. The third transparent member 180 is further included. On the optical axis C, the first transparent member 140, the first light conversion member 110, the third transparent member 180, the first heat transfer suppression member 130, the second light conversion member 120, Two transparent members 150 are arranged. The first heat transfer suppressing member 130 and the third transparent member 180 have a truncated cone shape, and the entire side surface 133 of the first heat transfer suppressing member 130 and the entire side surface 183 of the third transparent member 180 are the first holder 160. It is thermally connected to a tapered surface 165 that is an inner peripheral surface. The emission surface 112 of the first light conversion member 110 is laminated on the first surface 181 of the third transparent member 180, and the second surface 182 of the third transparent member 180 is laminated on the first surface 131 of the first heat transfer suppressing member 130. The second surface 132 of the first heat transfer suppressing member 130 is laminated on the incident surface 121. The third transparent member 180 has glass, for example. The thermal conductivity of the third transparent member 180 is 1 W / m · K. The third transparent member 180 is a transmission member that transmits the primary light and the first and second converted lights. Here, on the optical axis C, the thickness of the first heat transfer suppressing member 130 is 0.05 mm. The first surface 181 is smaller than the second surface 182. The first surface 181 and the second surface 182 are, for example, circular. For example, primary light and first converted light are incident on the first surface 181, and the second surface 182 emits, for example, primary light and first converted light. The first surface 181 may emit the second converted light, and the second converted light may enter the second surface 182.

  The thermal resistance values HR1, HR2, and HR3 on the optical axis C in the present modification are as follows.

HR1 = 0.25 × 10 ⁻³ [m] / 12 [W / (m · K)] = 2.1 × 10 ⁻⁵ [(m ² · K) / W)]
HR2 = 0.25 × 10 ⁻³ [m] / 1 [W / (m · K)] = 2.5 × 10 ⁻⁴ [(m ² · K) / W)]
HR3 = 0.05 × 10 ⁻³ [m] /0.2 [W / (m · K)] = 2.5 × 10 ⁻⁴ [(m ² · K) / W)]
Thus, the thermal resistance value HR3 on the optical axis C is larger than the thermal resistance value HR1 on the optical axis C and is the same as the thermal resistance value HR2 on the optical axis C.

  In the present modification, only one of the second light conversion members 120 has a heat resistance value HR3 that is larger than at least one of the first light conversion member 110 and the second light conversion member 120. The 1st heat transfer suppression member 130 should just be arrange | positioned. Thereby, for example, the first heat transfer suppression member 130 can suppress heat transfer from the first light conversion member 110 to the second light conversion member 120.

  In Modification 3 shown in FIG. 10, the first heat transfer suppressing member 130 and the third transparent member 180 are arranged between the first light conversion member 110 and the second light conversion member 120 in the optical axis C direction. . The first heat transfer suppressing member 130 is disposed on the optical axis C connecting the light emitting point p1 and the light emitting point p2, and the third transparent member 180 is disposed around the first heat transfer suppressing member 130. The third transparent member 180 has a truncated cone shape having, for example, a cylindrical hollow portion in which the first heat transfer suppressing member 130 is disposed. The first heat transfer suppression member 130 has, for example, a cylindrical shape. The first heat transfer suppressing member 130 only needs to have a column shape. The shape of the hollow portion is not particularly limited as long as the first heat transfer suppressing member 130 is disposed. The outer peripheral side surface 133 of the first heat transfer suppressing member 130 is thermally connected to the inner peripheral surface of the third transparent member 180. The entire side surface 183 of the third transparent member 180 is in contact with the tapered surface 165 that is the inner peripheral surface of the first holder 160. The diameter of the first heat transfer suppression member 130 of the present modification is smaller than the minimum diameter of the first heat transfer suppression member 130 of the first embodiment. Since the third transparent member 180 is disposed between the first heat transfer suppressing member 130 and the first holder 160 in the width direction of the light conversion unit 100 orthogonal to the optical axis C, the first heat transfer suppressing member 130 is There is no physical contact with the first holder 160.

  The first heat transfer suppressing member 130 includes, for example, a transparent resin having a thermal conductivity of 0.2 W / m · K. The third transparent member 180 includes, for example, glass having a thermal conductivity of 1 W / m · K.

  In the present modification, the first heat transfer suppressing member 130 is disposed on the optical axis C connecting the light emitting point p1 and the light emitting point p2. Therefore, heat transmitted between the first light conversion member 110 and the second light conversion member 120 on the optical axis C can be preferentially suppressed over heat transmitted on the tapered surface 165 side.

  In Modification 4 shown in FIG. 11, the light conversion unit 100 further includes a heat transfer member 190 that is rotationally symmetrical about the optical axis C. For example, the heat transfer member 190 is disposed between the first light conversion member 110 and the second light conversion member 120 in the optical axis C direction. The heat transfer member 190 is thermally connected to the first light conversion member 110 that generates a large amount of heat, is disposed away from the second light conversion member 120 that generates a small amount of heat, and is an inner peripheral surface of the first holder 160. Thermally connected to the tapered surface 165. The side surface 193 of the heat transfer member 190 is a tapered surface, and the entire side surface 193 is thermally connected to the tapered surface 165. The heat transfer member 190 may be disposed between the side surface 113 of the cylindrical first light conversion member 110 and the tapered surface 165 that is the inner peripheral surface of the first holder 160. The shape of the heat transfer member 190 is not particularly limited as long as the heat transfer member 190 is thermally connected to the first light conversion member 110 and the first holder 160.

  The heat transfer member 190 has a thermal conductivity higher than that of the first light conversion member 110. Such a high thermal conductive member includes, for example, a graphite sheet or zinc oxide. In the graphite sheet, the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction. Therefore, the heat transmitted from the first light conversion member 110 to the heat transfer member 190 is transmitted in the plane direction rather than the thickness direction, that is, transmitted from the heat transfer member 190 to the first holder 160. The thermal conductivity in the plane direction is, for example, 700 W / m · K. Zinc oxide is used as a transparent electrode. The thermal conductivity of zinc oxide is, for example, 25 W / m · K.

  When the heat transfer member 190 is colored like a graphite sheet, for example, the heat transfer member 190 is disposed in a region excluding the optical axis C that is the central axis of the primary light incident on the first holder 160. The For this reason, the heat transfer member 190 has, for example, a donut shape. When the heat transfer member 190 is transparent like zinc oxide used as a transparent electrode, the heat transfer member 190 may also be disposed on the optical axis C.

  When the heat transfer member 190 is disposed between the side surface 113 and the tapered surface 165, the heat transfer member 190 may be colored and non-transparent, or may be transparent.

  The heat generated from the first light conversion member 110 is transmitted to the first holder 160 via the heat transfer member 190 in addition to the second path R2, and is released to the outside from the first holder 160.

  In the present modification, the amount of heat transferred from the first light conversion member 110 to the first holder 160 by the heat transfer member 190 can be increased, and the heat dissipation of the first light conversion member 110 having a large amount of heat generation can be improved.

  In Modification 5 shown in FIG. 12, a heat transfer member 190 is disposed instead of the second transparent member 150. The heat transfer member 190 has a substantially truncated cone shape. The heat transfer member 190 is disposed closer to the holder emitting portion 164 that is the emitting portion side of the light conversion unit 100 than the incident surface 121 side of the second light converting member 120 irradiated with the primary light. The heat transfer member 190 includes a concave contact surface 191 on which the second light conversion member 120 is disposed, a large circular emission surface 192 facing the contact surface 191, and an outer peripheral surface between the contact surface 191 and the emission surface 192. And a side surface 193. The contact surface 191 of the heat transfer member 190 is thermally connected to the emission surface 122 and the side surface 123 of the second light conversion member. The entire side surface 193 is thermally connected to a tapered surface 165 that is an inner peripheral surface of the first holder 160.

  The heat transfer member 190 of this modification is a transmission member that transmits the primary light and the first and second converted lights. The heat transfer member 190 is a transparent ceramic having a thermal conductivity (12 W / m · K) higher than the thermal conductivity (1 W / m · K) of the glass-sealed green phosphor of the second light conversion member 120. . This ceramic is, for example, a YAG ceramic not doped with Ce.

  When the second light conversion member 120 is a resin-encapsulated green phosphor (thermal conductivity: 0.2 W / m · K), the heat transfer member 190 uses transparent glass (thermal conductivity: 1 W / m · K). can do. In this modification, the thermal conductivity of the first light conversion member 110 is higher than the thermal conductivity of the second light conversion member 120.

The heat transfer member 190 is disposed on the opposite side of the second light conversion member 120 from the first light conversion member 110 and on the side of the second light conversion member 120, and is thermally connected to the first holder 160. . Therefore, the heat generated from the second light conversion member 120 is not only transmitted from the second light conversion member 120, which is the fifth path R5, to the first holder 160 via the reflection member 170, but also the second light conversion member 120. The heat is transmitted to the first holder 160 via the heat transfer member 190 and is released to the outside from the first holder 160.
In this modification, heat can be easily escaped from the second light conversion member 120 depending on the arrangement position of the heat transfer member 190. Further, heat can be easily transferred from the second light conversion member 120 to the first holder 160 by the heat transfer member 190, and the heat dissipation of the second light conversion member 120 can be improved. In this modification, the heat transfer member 190 can reduce the amount of heat transferred from the second light conversion member 120 to the first light conversion member 110.

[Second Embodiment]
The second embodiment will be described with reference to FIG. The 1st light conversion member 110 of this embodiment is a wavelength conversion member similarly to 1st Embodiment. Therefore, the first converted light is first wavelength converted light such as yellow fluorescence. The second light conversion member 120 of this embodiment is a light distribution angle conversion member that does not convert the wavelength of the received primary light and emits light having a light distribution angle different from that of the primary light. For example, the second light conversion member 120 is, for example, a diffusion member that converts primary light into primary diffused light in which the spread angle of the primary light is widened. When the second light conversion member 120 converts the light distribution angle of the primary light, a conversion loss occurs, and the second light conversion member 120 absorbs a part of the primary light and generates heat.

  The second light conversion member 120 includes a sealing member (not shown) and a diffusion member (not shown) that is sealed by the sealing member in a state of being dispersed inside the sealing member and has a refractive index lower than the refractive index of the sealing member. Particles. The sealing member has, for example, a silicone resin having a refractive index of 1.4. The diffusion particles include, for example, alumina having a refractive index of 1.76 and an extinction coefficient of less than 0.1. The diffusion particles have a material that absorbs primary light. The diffusing particles have optical properties such as a complex refractive index N that is a combination of a specific refractive index n and an extinction coefficient k.

  The refractive index of the diffusing particles is preferably 1.41 or more. Further, it is more preferable that the difference between the refractive index of the diffusing particles and the refractive index of the sealing member is 0.2 or more, and the refractive index of the diffusing particles is 1.61 or more, thereby diffusing a lot of primary light. Is done. The smaller the extinction coefficient, the smaller the primary light quantity absorbed by the diffusing particles. Therefore, the diffusing particles are preferably made of a material having an extinction coefficient of 0.1 or less.

  The material of the diffusion particles is, for example, an inorganic material such as a metal or an inorganic oxide. Examples of the metal include aluminum, titanium, and zinc. Examples of the inorganic material include reflective diffusion particles or transmission diffusion particles such as titanium oxide, tantalum oxide, and aluminum oxide. The diffusion particles need not be composed of only one type of material, and may be composed of a plurality of types of materials.

  The increasing angle of the spreading angle of the primary light incident on the second light conversion member 120 is mainly the particle size of the diffusion particles, the concentration of the diffusion particles with respect to the sealing member, and the refractive index of the diffusion particles and the sealing member. And the thickness of the second light conversion member 120.

  The above-described particle size, concentration, refractive index, thickness, and the like are set so that the light distribution angle of the first-order diffused light is approximately equal to the light distribution angle of the first converted light emitted from the holder emitting portion 164.

  The second light conversion member 120 converts (diffuses) the light distribution angle with respect to the first converted light.

  In the present embodiment, the first converted light passes through the second light conversion member 120 and is emitted from the holder emitting portion 164 as illumination light. When the first converted light passes through the second light conversion member 120, the light distribution angle of the first converted light is spread by the second light conversion member 120, but is disposed in front of the second light conversion member 120. The reflection member 170 makes a narrow angle. Therefore, the light distribution characteristic of the first converted light approaches the light distribution characteristic shown in FIG.

  The second light conversion member 120 is irradiated with primary light that is not absorbed by the first light conversion member 110 and passes through the first light conversion member 110. The primary light is converted into primary diffused light by the second light conversion member 120. Although not shown, a part of the primary diffused light passes through the first heat transfer suppression member 130 from the incident surface 121 of the second light conversion member 120 and travels toward the first light conversion member 110. The primary diffused light is wavelength-converted by the first light conversion member 110 and emitted from the holder emitting portion 164 as first converted light (illumination light). Another part of the primary diffused light is emitted from at least one of the emission surface 122 and the side surface 123 of the second light conversion member 120. A portion of the primary diffused light does not travel to the reflecting member 170 but passes through the second transparent member 150 and is directly emitted forward from the emitting surface 152 (holder emitting portion 164). The other part of the primary diffused light is reflected by the reflecting member 170, and the traveling direction of the primary diffused light changes. The primary diffused light passes through the second transparent member 150 and is emitted forward from the holder emitting portion 164 without entering the first and second light conversion members 110 and 120 again. The light distribution angle of the primary diffused light becomes a narrow angle depending on the particle diameter, concentration, refractive index, thickness, and the like. Therefore, the light distribution characteristic of the first-order diffused light approaches the light distribution characteristic of the first converted light shown in FIG.

  When the second light conversion member 120 converts the light distribution angle of the primary light, a conversion loss occurs, and the second light conversion member 120 absorbs a part of the primary light and generates heat. Since this heat transfer is the same as in the first embodiment, a description thereof is omitted here.

  In the present embodiment, even if the first and second light conversion members 110 and 120 having different light conversion characteristics are arranged, the first and second light conversion members 110 and 120 are converted by the first heat transfer suppression member 130 during light conversion. It can suppress that the heat | fever generated from concentrates on the 1st, 2nd light conversion members 110,120. Moreover, the fall of the conversion efficiency accompanying the temperature rise of the 1st, 2nd light conversion members 110 and 120 can be suppressed, and the bright illumination light in which the light distribution of the primary diffused light aligned with the light distribution of the 1st converted light is realizable.

  The second light conversion member 120 is disposed inside the first holder 160 having a tapered shape whose diameter increases from the holder incident portion 163 to the holder emitting portion 164. Therefore, the light distribution of the primary diffused light can be narrowed, the light distribution angle conversion amount by the second light conversion member 120 can be suppressed within a predetermined range, in other words, the concentration of the diffused particles can be reduced, and the second light conversion member Heat generation due to 120 conversion loss can be reduced.

[Modification]
Hereinafter, modified examples 1 and 2 of the present embodiment will be described. In each modification, only differences from the present embodiment are mainly described. In FIG. 14, the second converted light (second wavelength converted light) that has been wavelength-converted by the second light conversion member 120 is omitted for clarity of illustration.

  In the first modification shown in FIG. 14, the first light conversion member 110 is a light distribution angle conversion member (diffusion member) similarly to the second light conversion member 120 of the second embodiment, and the second light conversion member 120 is the first light conversion member 120. It is a wavelength conversion member like 1 embodiment.

  Therefore, the 1st light conversion member 110 is a diffusion member which converts primary light into primary diffused light which extended the spreading angle of primary light, for example. When the first light conversion member 110 converts the light distribution characteristic of the primary light, a conversion loss occurs, and the first light conversion member 110 absorbs a part of the primary light and generates heat. The configuration of the first light conversion member 110 such as a sealing member and diffusing particles (not shown) is substantially the same as the configuration of the second light conversion member 120 of the second embodiment, and thus description thereof is omitted here.

  In this modification, the primary light first irradiates the first light conversion member 110 and is converted into primary diffused light by the first light conversion member 110. The primary diffused light passes through the first heat transfer suppression member 130 and the second light conversion member 120. A part of the primary diffused light is reflected by the reflecting member 170, and the traveling direction of the primary diffused light changes. The primary diffused light is transmitted through the second transparent member and emitted forward from the holder emitting portion 164 without re-entering the first and second light conversion members 110 and 120 and the first heat transfer suppressing member 130. Is done. Further, another part of the first-order diffused light does not travel to the reflecting member 170 but passes through the second transparent member and is directly emitted forward from the emitting surface 152 (holder emitting portion 164). That is, the primary diffused light is emitted without the traveling direction of the primary diffused light being changed by the reflecting member 170. Although not shown, another part of the primary diffused light irradiated on the second light conversion member 120 is wavelength-converted by the second light conversion member 120 and transmitted through the second transparent member 150 for second conversion. The light is emitted from the holder emitting portion 164 as light (illumination light).

  In this modification, when the primary diffused light irradiates the second light conversion member 120, the irradiation region 124 on the incident surface 121 can be expanded by diffusion. Therefore, local heat generation in the second light conversion member 120 with respect to the amount of primary light incident on the light conversion unit 100 can be alleviated, and a decrease in conversion efficiency of the second light conversion member 120 can be suppressed.

  In the second modification illustrated in FIG. 15, the light conversion unit 100 further includes a second heat transfer suppression member 220 and a third light conversion member 230. The second heat transfer suppression member 220 and the third light conversion member 230 are disposed rotationally symmetrically about the optical axis C. In order from the optical fiber emitting end 16 side, the first transparent member 140, the first light conversion member 110, the first heat transfer suppression member 130, the second light conversion member 120, the second heat transfer suppression member 220, and the third light conversion member. 230 and the second transparent member 150 are disposed. The second heat transfer suppression member 220 has a truncated cone shape, and the third light conversion member 230 has a cylindrical shape. The third light conversion member 230 may have a truncated cone shape. The entire side surface 223 of the second heat transfer suppressing member 220 and the entire periphery of the edge of the incident surface 231 of the third light conversion member 230 are thermally connected to a tapered surface 165 that is the inner peripheral surface of the first holder 160. The exit surface 122 of the second light conversion member 120 is laminated on the first surface 221 of the second heat transfer suppression member 220, and the second surface 222 of the second heat transfer suppression member 220 is the entrance surface 231 of the third light conversion member 230. Laminate to. The third light conversion member 230 is disposed on the concave contact surface 151, and the emission surface 232 and the side surface 233 of the third light conversion member 230 are in contact with the contact surface 151. The first surface 221 is smaller than the second surface 222. The first surface 221 and the second surface 222 are, for example, circular. For example, primary light and first and second converted light are incident on the second surface 221, and the second surface 222 emits, for example, primary light and first and second converted light. The first surface 221 may emit light whose optical characteristics have been converted by the third light conversion member 230, and light whose optical characteristics have been converted by the third light conversion member 230 may be incident on the second surface 222. The circular entrance surface 231 is the same size as the circular exit surface 232. For example, primary light and first and second converted light are incident on the incident surface 231, and the outgoing surface 232 emits, for example, first and second converted light and light whose optical characteristics have been converted by the third light converting member 230. .

  For example, the third light conversion member 230 may be a wavelength conversion member or a light distribution angle conversion member.

The second heat transfer suppressing member 220 includes a transparent silicone resin having a thermal conductivity of 0.2 W / m · K. The thermal resistance value of the second heat transfer suppression member 220 is substantially the same as the thermal resistance value HR3 of the first heat transfer suppression member 130. Note that the thermal conductivity of the first and second heat transfer suppression members 130 and 220 may be different from each other because of the magnitude relationship between the heat generation amounts of the first, second and third light conversion members 110, 120 and 230. The thermal resistance values of the two heat transfer suppression members 130 and 220 may be different from each other,
For example, it is assumed that the heat generation amount of the first light conversion member 110 is larger than the heat generation amount of the second light conversion member 120 and the heat generation amount of the second light conversion member 120 is larger than the heat generation amount of the third light conversion member 230. The thermal resistance value HR3 of the first heat transfer suppression member 130 disposed between the first light conversion member 110 and the second light conversion member 120 is between the second light conversion member 120 and the third light conversion member 230. The thermal conductivity and thickness of each of the first and second heat transfer suppression members 130 and 220 may be set so as to be larger than the thermal resistance value of the second heat transfer suppression member 220 disposed. Therefore, the heat transfer from the first light conversion member 110 that generates the most heat to the second and third light conversion members 120 and 230 can be suppressed by the first heat transfer suppression member 130.

  In this modification, the first and second heat transfer suppression members 130 and 220 can reduce the amount of heat transferred from the first, second, and third light conversion members 110, 120, and 230 to the other light conversion members, and heat can be reduced. It can be easily transmitted to the first holder 160. Therefore, it is possible to suppress the heat generated from the first, second, and third light conversion members 110, 120, and 230 from being concentrated on the first, second, and third light conversion members 110, 120, and 230 during the light conversion. , 3 The light conversion members 110, 120, and 230 can suppress a decrease in conversion efficiency due to a temperature rise, and provide bright illumination light.

  For example, one heat transfer suppressing member may be disposed between any of the three layers of the first, second, and third light conversion members 110, 120, and 230. Thereby, the amount of heat transferred from one light conversion member to the other light conversion member can be reduced.

[Third Embodiment]
A third embodiment will be described with reference to FIG. In the present embodiment, the light conversion unit 100 has a cylindrical second holder 240 that is separate from the first holder 160 and covers the first holder 160. The second holder 240 covers the first holder 160 when the first holder 160 is inserted into the second holder 240. At this time, the second holder 240 is thermally connected to the first holder 160. The second holder 240 may be brass like the first holder 160. In addition, since the calorific value of the 2nd light conversion member 120 which is a diffusion member mentioned later is smaller than the calorific value of the 1st light conversion member 110, the 2nd holder 240 does not need to be a member whose heat conductivity is as high as brass.

  The first light converting member 110 having a prismatic shape (for example, a cylindrical shape) is disposed in the vicinity of the holder emitting portion 164 in a state where the edge portion of the incident surface 111 is in contact with the tapered surface 165 over the entire circumference. For example, the emission surface 112 is arranged on the same plane as the holder emission part 164. Therefore, the second transparent member 150 is omitted, and the first transparent member 140 is filled in the hollow portion 162. As described in the first embodiment, the first light conversion member 110 is a wavelength conversion member such as a phosphor.

  The second light conversion member 120 is disposed at the end of the second holder 240. As described in the second embodiment, the second light conversion member 120 is a light distribution angle conversion member such as a diffusion member. Under the diffusion conditions of the diffusing member, the particle size, concentration, refractive index, thickness, etc. are set so that the primary diffused light has a wide light distribution.

  In a state where the second holder 240 covers the first holder 160, the first heat transfer suppression member 130 is formed between the first light conversion member 110 and the second light conversion member 120. The first heat transfer suppressing member 130 of the present embodiment uses an air layer having a thermal conductivity lower than the thermal conductivity (0.2 W / m · K) of the silicone resin.

  Since the 1st light conversion member 110 is arrange | positioned in the holder emission part 164 vicinity, the light distribution of the 1st conversion light radiate | emitted from the holder emission part 164 becomes a wide light distribution. The first converted light is further diffused by the second light conversion member 120.

  The primary light that is not absorbed by the first light conversion member 110 and irradiates the second light conversion member 120 is converted into a broad-distributed primary diffused light depending on the particle size, concentration, refractive index, thickness, etc. of the diffusion member. Is done.

  Most of the heat generated from the first light conversion member 110 is mainly transmitted to the first holder 160 and released to the outside from the first holder 160 through the second holder 240.

  Most of the heat generated from the second light conversion member 120 is mainly transmitted to the second holder 240 and released to the outside from the second holder 240.

  The first heat transfer suppressing member 130 uses an air layer. Therefore, the amount of heat transferred between the first and second light conversion members 110 and 120 can be reduced by the first heat transfer suppressing member 130.

  The first and second light conversion members 110 and 120 are held by a first holder 160 and a second holder 240 that are separate from each other. Based on the amount of heat generated by each of the first and second light conversion members 110 and 120, the materials of the first holder 160 and the second holder 240 can be selected as appropriate. Thereby, heat dissipation efficiency can be improved by the combination of materials.

  The first and second light conversion members 110 and 120 are disposed on the holder emitting portion 164 side. Therefore, the first converted light with the wide light distribution and the primary diffused light with the wide light distribution can be provided, and the light distribution characteristic of the first converted light and the light distribution characteristic of the primary diffused light can be made equal to each other.

[Fourth Embodiment]
The fourth embodiment will be described with reference to FIG. In this embodiment, two primary light sources are arranged. For convenience of explanation, they are referred to as primary light sources 11 and 11a. The primary light source 11 is the same as the primary light source 11 in the first embodiment. The primary light source 11a further includes a laser diode (hereinafter referred to as blue-violet LD 14a) that emits blue-violet laser light having an emission wavelength peak of 405 nm, and a light source driving unit 15a for driving the blue-violet LD 14a. . The blue-violet LD 14a is a second laser light source that emits second laser light that is primary light. The primary light in this embodiment is defined as blue laser light having an emission wavelength peak of 445 nm and blue-violet laser light having an emission wavelength peak of 405 nm.

  The light source control circuit 12 transmits a control signal for driving the blue LD 14 and the blue-violet LD 14a at a predetermined drive current and drive interval to the light source drive units 15 and 15a. Under the control of the light source control circuit 12, the blue LD 14 and the blue-violet LD 14a are switched and driven, or the blue LD 14 and the blue-violet LD 14a are driven simultaneously.

  The illuminating device 10 further includes an optical coupler 18 that combines the blue laser light emitted from the blue LD 14 and the blue-violet laser light emitted from the blue-violet LD 14 a and causes the combined light to enter the optical fiber 13. . The optical coupler 18 includes, for example, an optical demultiplexer.

  In the present embodiment, two optical fibers 13 are arranged, each incident end of the optical fiber 13 is connected to an optical coupler 18, and each optical fiber exit end 16 is independent from each other. Connected to. The primary light emitted from the optical coupler 18 enters each optical fiber 13 and is guided to each optical conversion unit 100 by each optical fiber 13. Each of the light conversion units 100 emits illumination light. The optical fibers 13 are separate from each other. The light conversion units 100 are separate from each other.

  The first light conversion member 110 that is YAG is hardly excited with respect to the blue-violet laser light and hardly generates yellow fluorescence. However, the first light conversion member 110 absorbs at least a part of the blue-violet laser light and generates heat.

  The second light conversion member 120, which is a glass-sealed green phosphor, excites the blue-violet laser light in the same manner as the blue laser light, generates green fluorescence with a predetermined conversion efficiency, and generates heat by the conversion loss. Occur. The second light conversion member 120 may include glass that is sealed in a state where the green phosphor and the diffusing particles are mixed.

  In the present embodiment, the operation of the illumination device 10 when only the blue LD 14 is driven is the same as the operation described in the first embodiment, and thus the description thereof is omitted. In addition, when the 2nd light conversion member 120 has glass as mentioned above, each light distribution angle of the 1st, 2nd conversion light and the primary diffused light which is blue laser diffused light becomes mutually equal.

  When only the blue-violet LD 14a is driven, most of the blue-violet laser beam is not absorbed by the first light conversion member that is YAG. A part of the blue-violet laser light is absorbed by the second light conversion member 120, which is a glass-sealed green phosphor, and wavelength-converted to green fluorescence. The light distribution characteristic of the second converted light by the blue-violet LD 14a is substantially equal to the light distribution characteristic of the second converted light by the blue LD 14. As described above, when the second light conversion member 120 includes glass, the light distribution angles of the second converted light and the primary diffused light that is blue-violet laser diffused light are equal to each other.

  When the blue LD 14 and the blue-violet LD 14a are driven simultaneously, the first and second converted lights that have been wavelength-converted by the blue laser light and the second converted light that has been wavelength-converted by the blue-violet laser light are the blue LD 14 and the blue-violet light. It is emitted as illumination light at a predetermined ratio according to the drive ratio with the LD 14a. Blue laser light and blue-violet laser light that are not absorbed by the first and second light conversion members 110 and 120 are also emitted as illumination light.

  When the drive ratio between the blue LD 14 and the blue violet LD 14a is changed, the ratio between the blue laser light and the blue violet laser light is changed, and the color of the illumination light is adjusted.

  In the present embodiment, the heat transfer when only the blue LD 14 is driven is the same as the heat transfer described in the first embodiment, and thus the description thereof is omitted.

  When only the blue-violet LD 14a is driven, the first light conversion member 110, which is YAG, does not absorb most of the blue laser light, but absorbs part of the blue laser light and generates heat. Moreover, the 2nd light conversion member 120 which is a glass sealing green fluorescent substance generate | occur | produces a heat | fever according to a predetermined wavelength conversion loss with a blue laser beam.

  As described above, when the second light conversion member 120 includes glass and only the blue LD 14 or the blue-violet LD 14a is driven, the second light conversion member is caused by the wavelength conversion loss of the green phosphor and the diffusion particles that are alumina. Heat is generated by the light distribution angle conversion loss.

  When only the blue-violet LD 14 a is driven, the heat generation amount of the second light conversion member 120 is larger than the heat generation amount of the first light conversion member 110. Similarly to the first embodiment, the heat transfer from the first light conversion member 110 to the second light conversion member 120 is suppressed by the first heat transfer suppression member 130, and the heat is transmitted with priority to the first holder 160. Is done. For this reason, the 1st heat transfer suppression member 130 suppresses effectively that one heat of the 1st and 2nd light conversion members 110 and 120 is transmitted to the other of the 1st and 2nd light conversion members 110 and 120. And reduction in wavelength conversion efficiency can be reduced.

  When the blue LD 14 and the blue-violet LD 14a are driven, heat generated from the first and second light conversion members 110 and 120 by two types of primary light moves between the first and second light conversion members 110 and 120. Is suppressed by the first heat transfer suppressing member 130 and is transmitted with priority to the first holder 160.

  In this embodiment, since the blue-violet LD 14a is added, two types of primary light can be switched and emitted, and the color of the illumination light can be switched. Thereby, the illumination light according to the observation mode of the to-be-observed body S can be provided.

  Even when blue-violet laser light is used, heat generated from the first and second light conversion members 110 and 120 can be prevented from concentrating on the first and second light conversion members 110 and 120, and the temperature rises. On the other hand, a decrease in conversion efficiency can be reduced, and bright illumination light can be provided.

  Even when blue laser light and blue-violet laser light are used simultaneously, heat generated from the first and second light conversion members 110 and 120 is concentrated on the first and second light conversion members 110 and 120. It is possible to suppress the decrease in conversion efficiency with respect to the temperature rise, and bright illumination light can be provided. Moreover, the illuminating device 10 which can adjust the color of illumination light can be provided by adjusting the ratio of blue laser light and blue-violet laser light.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, A various improvement and change are possible within the range which does not deviate from the summary of this invention.

Claims (24)

An illumination device having a light conversion unit that converts the optical characteristics of primary light and emits illumination light,
The light conversion unit is:
A first light conversion member and a second light conversion member that absorb part of the primary light, convert the optical characteristics of the absorbed primary light, and generate heat when converting the optical characteristics;
A heat transfer suppressing member having a thermal conductivity lower than the thermal conductivity of at least one of the first light conversion member and the second light conversion member;
Comprising
The first light conversion member is disposed away from the second light conversion member,
The heat transfer suppression member is disposed at least at a part between the first light conversion member and the second light conversion member, and the first light conversion member and the second light conversion member are connected to the first light conversion member. A lighting device that suppresses transmission of the heat to the other of the one light conversion member and the second light conversion member. The light conversion unit further includes a holder that holds the first light conversion member and the second light conversion member inside, and has a heat conductivity higher than the heat conductivity of the heat transfer suppression member,
A part of the first light conversion member is thermally connected to the holder;
In the transfer of heat generated from the first light conversion member, the first transfer amount of the heat transferred from the first light conversion member to the second light conversion member via the heat transfer suppression member is The lighting device according to claim 1, wherein the second amount of heat transferred from the first light conversion member to the holder is less than the second transfer amount. The holder is
A holder incident part on which the primary light is incident;
A holder emitting section for emitting the illumination light;
Have
At least a part of the first light conversion member and the second light conversion member is disposed on an optical axis that is a central axis of the primary light incident on the holder incident portion,
The first light conversion member is disposed between the holder incident portion and the second light conversion member,
The lighting device according to claim 2, wherein at least a part of the heat transfer suppression member is disposed in a region between the first light conversion member and the second light conversion member and including the optical axis.   The lighting device according to claim 3, wherein the heat transfer suppressing member is further disposed on a side of the first light conversion member. The first light conversion member converts the optical characteristics of the absorbed primary light and emits first converted light having optical characteristics different from the optical characteristics of the primary light,
The lighting device according to claim 3, wherein the heat transfer suppressing member has an optical characteristic that transmits at least a part of the primary light and the first converted light.   The lighting device according to claim 5, wherein the thermal conductivity of the heat transfer suppressing member is lower than the thermal conductivity of the first light conversion member.   The lighting device according to claim 6, wherein the thermal conductivity of the heat transfer suppressing member is less than 12 W / m · K.   The lighting device according to claim 7, wherein the heat transfer suppressing member has resin, glass, or a gap.   The thermal resistance value of the heat transfer suppression member on the optical axis is greater than the thermal resistance value of each of the first and second optical conversion members on the optical axis, or the first optical conversion member on the optical axis. The lighting device according to claim 3, wherein the lighting device has a larger thermal resistance value. The first and second light conversion members convert the optical characteristics of the absorbed primary light to emit first and second converted lights having optical characteristics different from the optical characteristics of the primary light,
The holder is
A through-hole portion penetrating the holder from the holder entrance portion to the holder exit portion;
A reflective member that is disposed on the inner peripheral surface of the through-hole portion and reflects the first converted light and the second converted light;
Have
The reflection member changes the light distribution of each of the first and second converted lights by reflection so that the light distribution angles of the first and second converted lights emitted from the holder emitting section are equal to each other. The lighting device according to claim 3.   The lighting device according to claim 10, wherein a thickness of the heat transfer suppressing member on the optical axis is thinner than a thickness of each of the first and second light conversion members on the optical axis. The intersection of the first incident surface of the first light conversion member to which the primary light is irradiated and the optical axis is defined as a substantial first light emission point of the first light conversion member, and the primary light is irradiated. When the intersection of the second incident surface of the second light conversion member and the optical axis is a substantial second light emission point of the second light conversion member,
The first light emission point and the second light emission point are arranged at a position that is 2/3 or less of the length of the holder from the holder incident part,
The lighting device according to claim 10, wherein each of the first and second converted lights is emitted in a state where a light distribution half-value angle of each of the first and second converted lights is 100 ° or less.   The lighting device according to claim 2, wherein the thermal conductivity of the holder is higher than the thermal conductivity of the first light conversion member and the thermal conductivity of the second light conversion member. The volume of the holder is larger than the volume of each of the first and second light conversion members,
The lighting device according to claim 13, wherein a surface area of the holder is larger than a surface area of each of the first and second light conversion members. The amount of heat generated by the first light conversion member is greater than the amount of heat generated by the second light conversion member,
The lighting device according to claim 13, wherein the thermal conductivity of the first light conversion member is higher than the thermal conductivity of the second light conversion member.   The illumination according to claim 15, wherein a first area where the first light conversion member is thermally connected to the holder is wider than a second area where the second light conversion member is thermally connected to the holder. apparatus. The light conversion unit further includes a heat transfer member having a thermal conductivity higher than the thermal conductivity of the first light conversion member,
The lighting device according to claim 15, wherein the heat transfer member is thermally connected to the first light conversion member and the holder. The light conversion unit further includes a heat transfer member having a heat conductivity higher than the heat conductivity of the second light conversion member,
The heat transfer member is disposed closer to the light output unit of the light conversion unit than the second incident surface of the second light conversion member to which the primary light is irradiated, and the heat transfer member is disposed between the second light conversion member and the holder. The lighting device according to claim 15, which is thermally connected.   The lighting device according to claim 13, wherein the thermal conductivity of the holder is 15 W / m · K or more. At least one of the first light conversion member and the second light conversion member is a wavelength conversion member that converts the wavelength of the primary light into wavelength converted light having a wavelength range different from that of the primary light,
The lighting device according to claim 1, wherein the wavelength conversion member has a characteristic that the wavelength conversion efficiency decreases due to a temperature increase caused by heat generation.   2. The illumination according to claim 1, wherein any one of the first light conversion member and the second light conversion member is a light distribution angle conversion member that emits light having a light distribution angle different from the primary light. apparatus.   The lighting device according to claim 21, wherein the first light conversion member and the second light conversion member are formed of an inorganic material. A primary light source that emits the primary light;
The primary light source has a first laser light source that emits a first laser light that is the primary light,
The illumination according to claim 1, wherein the primary light source is optically connected to the light conversion unit via an optical fiber that guides the primary light emitted from the primary light source to the light conversion unit. apparatus. The primary light source further includes a second laser light source that emits a second laser light that is the primary light having a wavelength different from that of the first laser light,
The illuminating device according to claim 23, further comprising an optical coupler that multiplexes the first laser light and the second laser light and makes the combined light enter the optical fiber.

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