TW202403225A - Fluorescent body device and light source module - Google Patents

Abstract

A fluorescent body device (1) comprises: a substrate member (10); and a wavelength conversion member (20) provided on the substrate member (10) and having a fluorescent section (21) and a light reflection section (22). The fluorescent section (21) has a light input surface (211) and a light output surface (212). The light reflection section (22) is provided so as to surround the fluorescent section (21) when observed from the direction of the light output surface (212). The main component of the fluorescent section (21) is a YAG fluorescent ceramic containing Ce3+. The main component of the light reflection section (22) is a light reflective ceramic. The Ce3+ concentration of the YAG fluorescent ceramic is 0.005-0.02%, and the thickness of the YAG fluorescent ceramic is 350-820 [mu]m.

Description

Phosphor components and light source modules

The invention relates to a phosphor element and a light source module.

Light source modules that use solid light-emitting elements such as LEDs (Light Emitting Diodes) or semiconductor lasers as light sources are used in projectors, endoscopes, vehicle headlights, lighting devices, or liquid crystal display devices. This type of light source module includes, for example, a light source and a phosphor element that uses the light emitted by the light source as excitation light to emit fluorescent light. In this case, light source modules used in projectors, endoscopes, etc. require high brightness, so semiconductor lasers are used as light sources.

As such a phosphor element, Patent Document 1 discloses an optical component including a light-transmitting member and a wavelength conversion member having a fluorescent part and a light-reflecting part arranged above the light-transmitting member. [Known technical documents] [Patent Document]

Patent Document 1: Japanese Patent Application Publication No. 2019-53130

[Problems to be solved by this invention]

On the other hand, in the phosphor element, light of a predetermined color is generated from the fluorescent part by irradiating the excitation light to the fluorescent part, and output light mixed with the excitation light and the generated light is emitted. Depending on the application, the chromaticity of the output light may be required to converge within a predetermined range. Furthermore, in certain applications, there are cases where it is required to make the angular dependence of the chromaticity of the output light small.

In view of these problems, an object of the present invention is to provide a phosphor element and the like in which the chromaticity of output light has small angle dependence. [Technical means to solve problems]

In order to achieve the above object, an aspect of the phosphor element of the present invention includes: a substrate member; and a wavelength conversion member having a fluorescent part and a light reflecting part, which are provided on the substrate member; the fluorescent part has a light incident surface and the light exit surface; when viewed from the direction of the light exit surface, the light reflection part is arranged around the phosphor part; the main component of the phosphor part is YAG phosphor ceramic containing Ce ³⁺ ; the The main component of the light reflective part is light reflective ceramic; the Ce ³⁺ concentration of the YAG phosphor ceramic is 0.005% or more and 0.02% or less; the thickness of the YAG phosphor ceramic is 350 μm or more and 820 μm or less.

In order to achieve the above object, one aspect of the light source module of the present invention includes the phosphor element described above. [Effects of the present invention]

According to the present invention, it is possible to provide a phosphor element, etc., in which the chromaticity of the output light has small angle dependence.

In addition, the implementation forms described below all show general cases or specific cases. The numerical values, shapes, materials, structural elements, arrangement positions and connection forms of the structural elements, steps, the order of the steps, etc. shown in the following embodiments are only examples and are not intended to limit the present invention. In addition, among the components of the following embodiments, components that are not described in the independent claims will be described as arbitrary components.

In addition, each diagram is a schematic diagram only and is not a strictly defined diagram. In addition, in each drawing, substantially the same structure is given the same reference numeral, and repeated description is omitted or simplified. In addition, in this specification, linear expansion rate and linear expansion coefficient have the same meaning.

In addition, in this specification, terms indicating the shape of elements, such as rectangle or circle, and numerical ranges do not merely indicate strictly defined expressions, but refer to substantially equivalent ranges, including, for example, differences of a few %. Performance.

In addition, in this specification, terms such as "upper" and "lower" do not refer to the absolute upper (vertical upper) and lower (vertical lower) spatial cognition, but refer to the order of stacking in a stacked structure. Use terms that accurately define relative positional relationships. In addition, terms such as "above" and "below" are applicable not only to the case where "two components are arranged with a gap from each other, and there are other components between the two components", but also when "the two components are arranged closely to each other" , two constituent elements are in contact".

(implementation form) [composition] First, the structure of the phosphor element 1 according to the embodiment will be described using FIG. 1 . FIG. 1 is a diagram showing the structure of the phosphor element 1 of this embodiment. In FIG. 1 , (a) is a plan view of the phosphor element 1, and (b) is a cross-sectional view of the phosphor element 1 taken along the line Ib-Ib in (a).

As shown in FIG. 1 , the phosphor element 1 of this embodiment includes a substrate member 10 and a wavelength conversion member 20 provided on the substrate member 10 . The substrate member 10 and the wavelength conversion member 20 are in direct thermal contact. The wavelength conversion member 20 is provided in direct contact with the top surface of the substrate member 10 . That is, there is no adhesive member such as an adhesive layer or a joint member such as a bonding layer between the substrate member 10 and the wavelength conversion member 20 . In addition, in this embodiment, the surface of the contact surface of the substrate member 10 that brings the substrate member 10 and the wavelength conversion member 20 into contact, or the contact surface of the wavelength conversion member 20 that brings the wavelength conversion member 20 and the substrate member 10 into contact is not perfect. Smooth situation. In this case, even if there is a partial space between the substrate member 10 and the wavelength conversion member 20, if there is a portion where the substrate member 10 and the wavelength conversion member 20 are in direct physical contact, it is still regarded as direct thermal contact. Furthermore, in this case, air exists in the above-mentioned part of the space. By bringing the substrate member 10 and the wavelength conversion member 20 into direct thermal contact, the heat generated by the wavelength conversion member 20 can be efficiently dissipated to the substrate member 10 , so that a highly efficient phosphor element 1 can be realized. In addition, by bringing the substrate member 10 and the wavelength conversion member 20 into direct thermal contact, the phosphor element 1 having a simple structure without using an adhesive member such as an adhesive layer or a joining member such as a bonding layer can be realized.

The substrate member 10 includes a light-transmitting base material 11 and a dielectric material multilayer film 12 and an anti-reflection film 13 provided on the light-transmitting base material 11 . Furthermore, the wavelength conversion member 20 is provided with a fluorescent part 21 that emits fluorescent light, and a light reflecting part 22 that reflects light.

The light-transmitting base material 11 of the substrate member 10 is a light-transmitting substrate and has a first surface 11a (top surface), which is the surface on the wavelength conversion member 20 side, and a second surface 11b (backward to the first surface 11a). bottom surface).

The light-transmitting substrate 11 is preferably a substrate with high light transmittance. Specifically, the light-transmitting base material 11 is preferably a transparent substrate with a transmittance high enough to allow the opposite side to be seen through the light-transmitting base material 11 . For example, the visible light transmittance of the light-transmitting base material 11 is preferably 60% or more, more preferably 80% or more, and further preferably 90% or more, but it is not limited to this form. In addition, the light-transmitting substrate 11 is preferably a substrate with high heat resistance. As such transparent substrates, an aluminum oxide substrate formed of Al ₂ O ₃ , an aluminum nitride substrate formed of AlN, or a gallium nitride substrate formed of GaN can be used. In this case, the main component of the material constituting the light-transmitting base material 11 is Al ₂ O ₃ , AlN, or GaN. In addition, the transparent substrate with high heat resistance and light transmittance is not limited to these transparent substrates, and may also be a transparent substrate such as a sapphire substrate or a glass substrate. As an example, the shape of the light-transmitting base material 11 is a rectangular thin plate with a length of 7.0 mm, a width of 7.0 mm, and a thickness of 1.0 mm.

The dielectric material multilayer film 12 is provided on the first surface 11a of the light-transmitting base material 11. In this embodiment, the dielectric material multilayer film 12 serves as the uppermost surface film of the substrate member 10 .

The dielectric material multilayer film 12 has a structure in which a plurality of dielectric material films are laminated, reflects specific light, and transmits other specific light. The dielectric material multilayer film 12 of this embodiment reflects the light emitted by the phosphor fluorescence of the phosphor part 21 of the wavelength conversion member 20 and transmits the excitation light incident on the phosphor element 1 . For example, when the fluorescent part 21 is made of yellow phosphor and the excitation light incident on the fluorescent element 1 is ultraviolet light or blue light, the dielectric material multilayer film 12 at least converts the light emitted by the fluorescent part 21 The yellow light is reflected and the ultraviolet or blue light of the excitation light is transmitted.

By disposing the dielectric material multilayer film 12 on the first surface 11a side (wavelength conversion member 20 side) of the light-transmitting base material 11 in this way, the fluorescent part of the wavelength conversion member 20 can be converted into light by the dielectric material multilayer film 12. Among the light emitted by 21, the light that has been directed to the substrate member 10 is reflected. Thereby, the light emitted from the fluorescent part 21 from the fluorescent element 1 can be increased.

The anti-reflection film 13 is provided on the second surface 11 b of the light-transmitting base material 11 . In this embodiment, the anti-reflection film 13 is a surface film serving as the lowermost layer of the substrate member 10 .

The anti-reflection film 13 may be a single-layer film or a multi-layer film. As an example, the antireflection film 13 is made of silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), aluminum oxide ( A multilayer film composed of at least two dielectric material films such as Al ₂ O ₃ ) and aluminum nitride (AlN).

By providing the anti-reflection film 13 on the second surface 11 b of the light-transmitting base material 11 in this way, the reflection of light incident on the phosphor element 1 from the second surface 11 b side of the light-transmitting base material 11 can be suppressed. Thereby, the light incident on the light-transmitting base material 11 from the second surface 11b side of the light-transmitting base material 11 can be efficiently introduced into the light-transmitting base material 11 . Specifically, the excitation light incident on the phosphor element 1 in order to cause the phosphor portion 21 to emit fluorescent light can be efficiently introduced into the light-transmitting base material 11 .

The wavelength conversion member 20 is provided on the substrate member 10 , more specifically, above the substrate member 10 .

The fluorescent portion 21 of the wavelength conversion member 20 is a light-emitting layer that emits light and is excited by excitation light to fluoresce light of a predetermined wavelength in the visible light range. As an example, the fluorescent part 21 is a yellow phosphor layer composed of yellow phosphor. In this case, the yellow phosphor layer, that is, the fluorescent portion 21, uses light with a shorter wavelength than yellow light (for example, ultraviolet to blue light) as excitation light to emit fluorescence. That is, in the yellow phosphor layer, the wavelength of the excitation light is converted into yellow light with a longer wavelength than the excitation light.

The fluorescent part 21 is a phosphor layer formed only of phosphor. Specifically, the phosphor portion 21 is a phosphor ceramic layer composed of a single crystal phase phosphor after sintering, and the main component is phosphor ceramic. As will be described later, the phosphor portion 21 is a yellow phosphor layer formed of a YAG (yttrium aluminum garnet) phosphor containing Ce ³⁺ . That is, the main component of the phosphor part 21 is YAG phosphor ceramic containing Ce ³⁺ ; more specifically, the phosphor part 21 is a member formed only of YAG phosphor ceramic containing Ce ³⁺ . In other words, the fluorescent part 21 does not have an adhesive or the like. In addition, the Ce ³⁺ concentration of the YAG phosphor ceramic containing Ce ³⁺ in the fluorescent part 21 is 0.005% or more and 0.02% or less. By setting the Ce ³⁺ concentration to 0.005% or more and 0.02% or less, it becomes a YAG phosphor ceramic with less temperature quenching (a decrease in the conversion efficiency of the phosphor due to temperature rise), so it is possible to achieve high efficiency. Phosphor element 1.

In this way, by using the phosphor ceramic layer as the phosphor portion 21, heat resistance and heat dissipation can be improved. In addition, by using a phosphor ceramic layer as the fluorescent part 21, light loss caused by scattering of fluorescent light can be suppressed, so the conversion efficiency of the fluorescent part 21 can be improved. In this embodiment, the fluorescent part 21 is a phosphor ceramic layer formed only of a single crystal phase.

The fluorescent part 21 contains a crystal phase having a garnet structure. More specifically, in this embodiment, the fluorescent part 21 is composed only of a crystal phase having a garnet structure. That is, the fluorescent portion 21 of this embodiment does not include a crystal phase having a structure different from the garnet structure. The garnet structure is a crystal structure represented by the general formula of A ₃ B ₂ C ₃ O ₁₂ . For element A, use rare earth elements such as Ca, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Lu; for element B, use elements such as Mg, Al, Si, Ga and Sc; for element C , using elements such as Al, Si and Ga. Examples of such garnet structures include YAG (yttrium aluminum garnet), LuAG (gallium aluminum garnet), Lu ₃ Ga ₂ (AlO ₄ ) ₃ (gallium aluminum garnet), and Y ₃ Ga ₂ (AlO ₄ ). ₃ (yttrium gallium aluminum garnet), Lu ₂ CaMg ₂ Si ₃ O ₁₂ (yttrium gallium aluminum garnet) and TAG (terbium aluminum garnet), etc. As a Ce ³⁺ activated phosphor, it is appropriate to use this garnet structure. In this embodiment, the material of the phosphor constituting the phosphor part 21 is (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ (that is, (Y _1-x Ce _x ) ₃ Al ₅ O ₁₂ ) The crystal phase represented by (0.00005≦x<0.0002) is composed of YAG; the fluorescent part 21 is a phosphor ceramic layer formed only of sintered YAG. Specifically, the fluorescent part 21 is a yellow phosphor layer formed of YAG phosphor.

In addition, the crystal phase constituting the fluorescent part 21 may also be a solid solution of a plurality of garnet crystal phases with different chemical compositions. Examples of such solid solutions include the garnet crystal phase represented by (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ (0.00005≦x<0.0002) and the garnet crystal phase represented by (Lu _1-d Ce _d ) ₃ Solid solution of garnet crystal phase represented by Al ₂ Al ₃ O ₁₂ (0.00005≦d<0.0002) ((1-a)(Y _1-x Ce _x ) ₃ Al ₅ O ₁₂・a(Lu _1-d Ce _d ) ₃ Al ₂ Al ₃ O ₁₂ (0＜a＜1)). Examples of such solid solutions include the garnet crystal phase represented by (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ (0.00005≦x<0.0002) and the garnet crystal phase represented by (Lu _1-z Ce _z ) ₂ CaMg ₂ Si ₃ O ₁₂ (0.00005≦z<0.0002) solid solution of garnet crystal phase ((1-b)(Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂・b(Lu _1-z Ce _z ) ₂ CaMg ₂ Si ₃ O ₁₂ (0＜b＜1)) etc. By making the fluorescent part 21 consist of a solid solution of a plurality of garnet crystal phases with different chemical compositions, the fluorescence spectrum of the fluorescent light emitted by the fluorescent part 21 is broadened and the green light component is increased. with red light component. Therefore, the phosphor element 1 that emits output light with a wide color gamut can be provided.

In addition, the crystal phase constituting the fluorescent portion 21 may include a crystal phase whose chemical composition is shifted from the crystal phase represented by the general formula A ₃ B ₂ C ₃ O ₁₂ described above. Examples of such crystal phases include (Y _1-x Ce _x ) which is rich in aluminum relative to the crystal phase represented by (Y _1-x Ce x ) ₃ Al ₂ Al ₃ O ₁₂ (0.00005≦x<0.0002 ₎ . ₃ Al _2+δ Al ₃ O ₁₂ (δ is a positive number). Examples of such crystal phases include (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ (0.00005≦x<0.0002) which is _yttrium- rich. _x ) _3+ζ Al ₂ Al ₃ O ₁₂ (ζ is a positive number), etc. These crystal phases deviate in chemical composition from the crystal phase represented by the general formula A ₃ B ₂ C ₃ O ₁₂ , but maintain the garnet structure. Since the fluorescent part 21 is composed of a crystalline phase that shifts the chemical composition, regions with different refractive indexes are generated in the fluorescent part 21 , so the excitation light and fluorescent light are further scattered, increasing the light-emitting area of the fluorescent part 21 become smaller.

Furthermore, as the material constituting the phosphor portion 21, the following materials that are Cr ³⁺ activated phosphors can also be used. This material is composed of Y ₃ Al ₂ (AlO ₄ ) ₃ : Cr ³⁺ , La ₃ Al ₂ (AlO ₄ ) ₃ : Cr ³⁺ , Gd ₃ Al ₂ (AlO ₄ ) ₃ : Cr ³⁺ , Y ₃ Ga ₂ (AlO ₄ ) ₃ : Cr ³⁺ , La ₃ Ga ₂ (AlO ₄ ) ₃ : Cr ³⁺ , Gd ₃ Ga ₂ (AlO ₄ ) ₃ : Cr ³⁺ , Y ₃ Sc ₂ (AlO ₄ ) ₃ : Cr ³⁺ , La ₃ Sc ₂ (AlO ₄ ) ₃ : Cr ³⁺ , Gd ₃ Sc ₂ (AlO ₄ ) ₃ : Cr ³⁺ , Y ₃ Ga ₂ (GaO ₄ ) ₃ : Cr ³⁺ , La ₃ Ga ₂ (GaO ₄ ) ₃ : Cr ³⁺ , (Gd,La) ₃ Ga ₂ (GaO ₄ ) ₃ : Cr ³⁺ , Gd ₃ Ga ₂ (GaO ₄ ) ₃ : Cr ³⁺ , Y ₃ Sc ₂ (GaO ₄ ) ₃ : Cr ³⁺ , La ₃ Sc ₂ (GaO ₄ ) ₃ : Cr ³⁺ , Gd ₃ Sc ₂ (GaO ₄ ) ₃ : Cr ³⁺ , (Gd,La) ₃ (Ga,Sc) ₂ (GaO ₄ ) At least one selected from the group consisting of ₃ : Cr ³⁺ , Ga ₂ O ₃ : Cr ³⁺ , and (Ga,Sc) ₂ O ₃ : Cr ³⁺ . In addition, the fluorescent part 21 may also be a solid solution of a Cr ³⁺ activated phosphor material.

The density of the phosphor part 21 (that is, the density of the YAG phosphor ceramic) is preferably not less than 90% and not more than 100% of the theoretical density, more preferably not less than 95% and not more than 100% of the theoretical density, and further preferably not less than 98% of the theoretical density. Above 100% below. Here, the theoretical density is the density in which the atoms in the layer are ideally arranged. In other words, the theoretical density is a value calculated based on the crystal structure assuming that there are no voids in the fluorescent part 21 . For example, when the density of the fluorescent part 21 is 99%, the remaining 1% corresponds to the void. That is, the higher the density of the fluorescent part 21 is, the fewer the gaps are. If the density of the fluorescent portion 21 is within the above range, the total amount of fluorescent light emitted by the fluorescent portion 21 increases, so that a fluorescent element 1 that emits a greater amount of light can be provided.

In addition, the density of the fluorescent part 21 is preferably 4.10g/cm ³ or more and 4.55g/cm ³ or less, more preferably 4.32g/cm ³ or more and 4.55g/cm ³ or less, further preferably 4.46g/cm 3 or more and 4.55g/cm ³ g/cm ³ or less. As shown in this embodiment, when the fluorescent part 21 is composed of YAG, if the density of the fluorescent part 21 is within the above range, the density of the fluorescent part 21 becomes 90% to 100% and 95% of the theoretical density respectively. % or more and less than 100%, and 98% or more and less than 100%. By setting the density of the fluorescent part 21 within the above range, the fluorescent part 21 can efficiently convert the absorbed excitation light into fluorescent light. That is, the fluorescent part 21 with high luminous efficiency is realized.

The fluorescent portion 21 has a rectangular shape in plan view, but is not limited to this shape. The fluorescent part 21 may also be circular in plan view. As an example, the plan view shape of the fluorescent part 21 is a rectangle with a length of 0.8 mm and a width of 0.8 mm.

In addition, the thickness of the fluorescent part 21 (that is, the thickness of the YAG phosphor ceramic) is 350 μm or more and 820 μm or less. This thickness is very thick, thereby ensuring heat dissipation from the side of the fluorescent part 21 . In addition, the thickness of the fluorescent part 21 is constant, but is not limited to this form. In addition, the thickness of the fluorescent part 21 may be 350 μm or more and 805 μm or less, or may be 400 μm or more and 805 μm or less.

The fluorescent part 21 has a light incident surface 211, a light exit surface 212, and side surfaces (four side surfaces 213 to 216). The light incident surface 211 is a surface on which the excitation light for exciting the fluorescent part 21 is incident, and is the bottom surface of the fluorescent part 21 . The light exit surface 212 is the surface from which the fluorescent part 21 emits fluorescent light, and is the top surface of the fluorescent part 21 . That is, the light incident surface 211 and the light exit surface 212 are surfaces facing away from each other. The four side surfaces 213 to 216 are lateral surfaces of the fluorescent part 21 . Each of the four side surfaces 213 to 216 is a plane orthogonal to the light incident surface 211 and the light exit surface 212 . The two side surfaces 213 and 215 are surfaces facing away from each other, and the two side surfaces 214 and 216 are surfaces facing away from each other.

When viewed from the direction of the light exit surface 212 , that is, when viewed from above, the light reflecting portion 22 of the wavelength converting member 20 is provided around the fluorescent portion 21 . In this embodiment, when viewed from above, the light reflecting portion 22 entirely surrounds the fluorescent portion 21 . That is, the light reflecting portion 22 is in contact with the entire four side surfaces 213 to 216 of the fluorescent portion 21 . Specifically, since the fluorescent part 21 has a rectangular plan view shape, the light reflecting part 22 has a rectangular opening. Specifically, the light reflecting portion 22 has a plan view shape of a rectangular frame having a rectangular opening and a rectangular outer shape. In addition, the plan view shape of the light reflecting portion 22 is not limited to a rectangular frame shape, and may also be annular or the like. As an example, the outer shape of the light reflecting portion 22 is 7.0 mm in length and 7.0 mm in width in plan view. In addition, in this embodiment, the thickness of the light reflection part 22 is the same as the thickness of the fluorescent part 21, but it is not limited to this form.

The light reflecting part 22 is in thermal contact with the fluorescent part 21. That is, the fluorescent part 21 and the light reflecting part 22 are provided so that the heat generated in the fluorescent part 21 can be conducted to the light reflecting part 22. In this embodiment, the light reflecting part 22 is in physical contact with the fluorescent part 21. Specifically, the entire inner peripheral side surface of the light reflecting portion 22 is brought into contact with the outer peripheral side surface of the fluorescent portion 21 . That is, the fluorescent portion 21 is provided to fill the opening of the light reflecting portion 22 .

In addition, the thickness (height) of the light reflection part 22 is the same as the thickness (height) of the fluorescent part 21, but it is not limited to this form. That is, the thickness of the light reflecting part 22 may be lower than the thickness of the fluorescent part 21 , or may be higher than the thickness of the fluorescent part 21 . However, the light reflecting portion 22 is preferably provided so as not to reach the top surface of the fluorescent portion 21 . That is, the light reflecting portion 22 is preferably formed so that the material (adhesive, etc.) constituting the light reflecting portion 22 does not protrude from the top surface of the fluorescent portion 21 .

The main component of the light reflective part 22 is light reflective ceramics, and the main component of the light reflective ceramics is alumina ceramics. That is, here, the light reflecting portion 22 is composed of a ceramic layer made of a ceramic material such as aluminum oxide (aluminum oxide (Al ₂ O ₃ )). More specifically, the light reflecting portion 22 is an alumina ceramic layer formed only of alumina. In other words, the light reflecting part 22 does not have an adhesive or the like. In this embodiment, the light reflection part 22 reflects the light of the wavelength in the visible light band, so it is white. That is, the light reflecting part 22 is a white ceramic layer. In addition, if the light reflection part 22 has the function of reflecting visible light, it does not need to be made of ceramics. For example, the light reflection part 22 may also be made of white resin or metal containing light reflective particles.

Inside the light reflecting part 22 (that is, the light reflecting ceramic), there are countless light scattering parts 23 for scattering and reflecting light. Specifically, when the light reflecting part 22 is a ceramic layer, there are countless voids (air layers) as the light scattering part 23 inside the ceramic layer in order to scatter and reflect light.

The density of the light reflective portion 22 (that is, the density of the light reflective ceramic) is preferably 98% or less of the theoretical density, more preferably 95% or less, and further preferably 90% or less.

The fluorescent part 21 of this embodiment is a phosphor ceramic layer formed only of sintered phosphors, and the light reflecting part 22 is a ceramic layer made of alumina ceramic. This makes it easy to integrate the fluorescent part 21 and the light reflecting part 22 .

Next, the structure of the light source module 100 using the phosphor element 1 of this embodiment and the optical function of the phosphor element 1 will be described using FIG. 2 . FIG. 2 is a diagram showing the structure of the light source module 100 of this embodiment.

The light source module 100 of this embodiment includes a phosphor element 1 and a light source 2 that emits light incident on the phosphor element 1 . The light source module 100 can be used as a light-emitting device provided in an endoscope, for example.

The light source 2 is an excitation light source and emits excitation light for causing the fluorescent part 21 of the wavelength conversion member 20 to emit light. The phosphor contained in the fluorescent part 21 is excited by the excitation light emitted from the light source 2 and emits fluorescent light. In this embodiment, the light source module 100 is a transmission-type light-emitting device that transmits the excitation light incident on the phosphor element 1 through the phosphor element 1 . That is, the excitation light incident on the phosphor element 1 is transmitted through the wavelength conversion member 20 . Therefore, the light source 2 is arranged so that the light emitted by the light source 2 is transmitted through the phosphor element 1 . Specifically, the light source 2 is arranged below the phosphor element 1 (on the substrate member 10 side).

As the light source 2, for example, a semiconductor laser that emits laser light of ultraviolet light or blue light can be used. Laser light has good linear propagation, so by using a semiconductor laser as the light source 2, the laser light (excitation light) can be incident on the fluorescent part 21 at a desired incident angle. In addition, the light source 2 is not limited to a semiconductor laser, and may also be other solid light emitting devices such as LEDs, or an excitation light source other than solid light emitting devices.

In the light source module 100 configured in this manner, the light emitted from the light source 2 is incident on the phosphor element 1, so that the phosphor element 1 emits output light of a predetermined color. More specifically, output light of a predetermined color is emitted from the light exit surface 212 of the fluorescent part 21 .

Specifically, in this embodiment, the light (excitation light) emitted from the light source 2 is incident on the back surface of the substrate member 10 . The light (excitation light) incident on the light source 2 of the substrate member 10 is transmitted through the substrate member 10 and reaches the fluorescent part 21 of the wavelength conversion member 20 . That is, the excitation light emitted from the light source 2 enters the fluorescent part 21 from the light incident surface 211 of the fluorescent part 21 . At this time, the outer dimensions of the fluorescent part 21 are preferably the same as the spot size (spot size of the excitation light) when the light emitted from the light source 2 is incident on the fluorescent part 21 .

In this embodiment, the excitation light of the light source 2 is blue light, and the fluorescent part 21 is a yellow phosphor layer. In this case, the blue light of the light source 2 enters the fluorescent part 21 . Thereby, the yellow phosphor (YAG phosphor) of the fluorescent part 21 absorbs part of the blue light of the light source 2 and is excited, and emits yellow light as fluorescent light. In the fluorescent part 21, the yellow light is mixed with the blue light of the light source 2 that has not been absorbed by the yellow phosphor to become white light, and the white light is emitted from the fluorescent part 21 as output light. That is, the output light (white light) is taken out from the wavelength converting member 20 .

On the substrate member 10, a dielectric material multilayer film 12 is formed that reflects the yellow light emitted by the fluorescent portion 21 and transmits the blue light of the excitation light. With this configuration, the light of the yellow light emitted by the fluorescent part 21 that goes to the light source 2 side is reflected by the dielectric material multilayer film 12 and travels to the side opposite to the light source 2 side.

In addition, a white light reflecting portion 22 is formed around the fluorescent portion 21 . With this configuration, the light traveling toward the lateral side among the output light (white light) emitted from the fluorescent part 21 is reflected by the light reflecting part 22, returns to the fluorescent part 21, and is radiated to the outside from the fluorescent part 21. . Thereby, the amount of light taken out from the fluorescent part 21 can be increased.

In addition, in this embodiment, the phosphor element 1 is a remote phosphor type, and the phosphor element 1 and the light source 2 are spatially separated and arranged. Thereby, it is possible to control the influence of the phosphor element 1 (especially the phosphor part 21 ) by the heat generated in the light source 2 .

In addition, in FIG. 2 , the light emitted from the light source 2 is incident perpendicularly on the back surface of the substrate member 10 , but it may be incident obliquely on the back surface of the substrate member 10 .

For example, when the light source module 100 is used as an endoscope, a light guide (not shown) is provided above the phosphor element 1, and the output light incident on the light guide is used as the endoscope. Use light. The more light that is incident on the light guide member among the output light output from the phosphor element 1, the higher the utilization efficiency of the output light. The light guide is an optical component composed of lenses, rod integrators, etc.

In addition, as mentioned above, the output light is white light, so the light source module 100 of this embodiment is a white light source module.

[Comparison with comparative examples] Next, the operation and effect of the phosphor element 1 of this embodiment will be described in comparison with the phosphor element 1x of the comparative example. FIG. 3 is a diagram showing the structure of the phosphor element 1x of the comparative example.

As shown in FIG. 3 , the phosphor element 1x of the comparative example includes a substrate member 10 and a wavelength conversion member 20x arranged above the substrate member 10 . In addition, the wavelength conversion member 20x is composed of a fluorescent part 25x and an adhesive 26x.

In the phosphor element 1x of the comparative example configured in this way, as shown in FIG. 3 , in the same manner as the phosphor element 1 of the present embodiment described above, by making the excitation light incident on the fluorescent part of the wavelength conversion member 20x 25x and emits white light.

FIG. 4 is a diagram showing a table of components of the phosphor element 1 of this embodiment and the phosphor element 1x of the comparative example.

The wavelength conversion member 20x included in the phosphor element 1x of the comparative example is different from the wavelength conversion member 20 of the embodiment in that it does not include the light reflecting portion 22 . In addition, as shown in FIG. 4 , the density of the light reflection portion 22 included in the wavelength conversion member 20 of the embodiment is 81.1% of the theoretical density.

The light-emitting area is approximately 0.34mm ² in the comparative example and approximately 0.64mm ² (0.8mm×0.8mm) in the embodiment. In addition, as shown in FIGS. 3 and 4 , the fluorescent portion 25x is a phosphor particle, more specifically, a phosphor particle composed of YAG. The adhesive 26x is a material used to hold and adhere the fluorescent part 25x above the substrate member 10, and is, for example, a transparent ZnO crystal.

In the comparative example, the refractive index of the wavelength conversion member 20x formed by the fluorescent part 25x and the adhesive 26x is approximately 1.95, and the refractive index of the fluorescent part 21 is 1.83.

The Ce ³⁺ concentration of the YAG constituting the fluorescent part 25x in the comparative example is approximately 0.1%, and the Ce ³⁺ concentration of the YAG constituting the fluorescent part 21 in the embodiment is 0.01%. The thickness of the wavelength conversion member 20x in the comparative example is approximately 20 μm, and the thickness of the fluorescent part 21 in the embodiment is 500 μm or more and 700 μm or less. In addition, the density of the fluorescent part 21 is 98.8% of the theoretical density.

In the luminescence image, the distribution of brightness when excitation light is irradiated is displayed as a gradient. In the embodiment, it was found that the entire fluorescent part 21 (that is, the entire approximately 0.64 mm ² of 0.8 mm×0.8 mm) emits light uniformly.

Here, the light emission characteristics will be described using FIG. 5 . FIG. 5 is a graph showing the light emission characteristics of the phosphor element 1 of this embodiment and the phosphor element 1x of the comparative example.

The horizontal axis of FIG. 5 represents the electric power (input electric power) input to emit the excitation light from the light source 2 . The vertical axis of FIG. 5 represents the total luminous flux of light incident on the light guide provided above the phosphor element 1 and the phosphor element 1x and emitted from the light guide. In addition, below, the light emitted from this light guide may be called light guide light.

As shown in FIG. 5 , regardless of the input power, the total luminous flux of the light guide light based on the output light output from the phosphor element 1 is larger than the total luminous flux of the light guide light based on the output light output from the phosphor element 1x. Higher luminous flux. For example, when the input power is about 6W, the total luminous flux of the light guide light based on the output light output from the phosphor element 1 is larger than the total luminous flux of the light guide light based on the output light output from the phosphor element 1x 30% higher. Furthermore, for example, when the input power is about 13 W, the total luminous flux of the light guide light based on the output light output from the phosphor element 1 is larger than that of the light guide light based on the output light output from the phosphor element 1x. The total luminous flux is 46% higher. In this way, the main reason why the phosphor element 1 of this embodiment has higher light emission characteristics than the phosphor element 1x of the comparative example will be described below.

The fluorescent element 1 is provided with a light reflecting portion 22 . Therefore, among the output light (white light) emitted from the fluorescent part 21 , the light traveling toward the lateral side is reflected by the light reflecting part 22 , returns to the fluorescent part 21 , and is emitted from the fluorescent part 21 to the outside. That is, it is suppressed that the light traveling toward the lateral side among the output light (white light) emitted from the fluorescent part 21 becomes unusable light. Therefore, the total luminous flux of the light guide light based on the output light output from the phosphor element 1 becomes higher.

In addition, in the phosphor element 1, a phosphor ceramic layer is used as the phosphor portion 21. Therefore, the heat resistance and heat dissipation of the fluorescent part 21 can be improved, and the luminous efficiency of the fluorescent part 21 is less likely to be reduced due to heat. In particular, if the density of the fluorescent part 21 (that is, the density of the YAG phosphor ceramic) is within the above range, it is unlikely that the luminous efficiency of the fluorescent part 21 will be reduced due to heat. In addition, by using a phosphor ceramic layer as the fluorescent part 21, light loss caused by scattering of fluorescent light can be suppressed, so the conversion efficiency of the fluorescent part 21 can be improved. Therefore, the total luminous flux of the light guide light based on the output light output from the phosphor element 1 becomes higher.

In this way, the phosphor element 1 of this embodiment has higher light emission characteristics than the phosphor element 1x of the comparative example.

[Angle dependence of chromaticity] Here, the angle dependence of the chromaticity of the output light of the phosphor element 1 of this embodiment will be further described.

Here, in order to examine the influence of the Ce ³⁺ concentration and thickness of the fluorescent part 21 on the angle dependence of the chromaticity of the output light, Review Examples 1 to 7 and Examples 1 to 1 were produced. 4 phosphor components, i.e. 11 samples. The phosphor elements of Review Examples 1 to 7 and Examples 1 to 4 were each produced so that the Ce ³⁺ concentration and thickness were different.

First, using the phosphor element 1a of Example 1, the structures of the phosphor elements of Review Examples 1 to 7 and Examples 1 to 4 will be described.

FIG. 6 is a cross-sectional view of the phosphor element 1a of Example 1. The fluorescent element 1a includes a substrate member 10a and a fluorescent part 21a. The substrate member 10 a has a structure in which the anti-reflection film 13 is removed from the substrate member 10 , that is, it has a light-transmitting base material 11 and a dielectric material multilayer film 12 provided on the light-transmitting base material 11 . Here, the phosphor portion 21a of the phosphor element 1a has a structure that is in contact with the phosphor element except for the point where it is in contact with the upper side of the dielectric material multilayer film 12 and the point where the light reflection portion 22 is not provided around it. The fluorescent part 21 included in 1 has the same structure. In addition, in the fluorescent part 21a of Example 1, the Ce ³⁺ concentration is 0.01% and the thickness is 705 μm.

The phosphor elements of Review Examples 1 to 7 and Examples 2 to 4 each have the same structure as the phosphor element 1a except for the Ce ³⁺ concentration and thickness of the phosphor part. More specifically, the Ce ³⁺ concentration and thickness of the fluorescent part were 0.08% and 225 μm in Review Example 1, 0.08% and 125 μm in Review Example 2, and 0.08% and 57 μm in Review Example 3, respectively. In addition, the Ce ³⁺ concentration and thickness of the fluorescent part were respectively 0.03% and 666 μm in Review Example 4, 0.03% and 400 μm in Review Example 5, and 0.03% and 300 μm in Review Example 6. In addition, the Ce ³⁺ concentration and thickness of the fluorescent part were 0.01% and 659 μm in Example 2, 0.01% and 400 μm in Example 3, 0.01% and 805 μm in Example 4, and 0.01 in Review Example 7. % and 300μm.

In addition, the phosphor elements of Examples 1 to 4 are equivalent to the phosphor element 1 of this embodiment from the viewpoint of Ce ³⁺ concentration and thickness.

Here, the manufacturing method of the phosphor element of Review Example 1 - Review Example 7, and Example 1 - Example 4 is demonstrated. Table 1 shows the target composition, raw materials used, and raw material blending ratios of the phosphor parts (YAG phosphor ceramics) used in the phosphor elements of Review Examples 1 to 7, and Examples 1 to 4. table.

[Table 1] Goal composition Ce ³⁺ concentration Raw materials used and raw material blending ratio Y ₂ O ₃ Al ₂ O ₃ CeO ₂ Review Example 1 ~ Review Example 3 (Y _0.9992 Ce _0.0008 ) ₃ Al ₅ O ₁₂ 0.08% 24.1990g 18.2090g 0.0295g Review Example 4 ~ Review Example 6 (Y _0.9997 Ce _0.0003 ) ₃ Al ₅ O ₁₂ 0.03% 24.2111g 18.2090g 0.0111g Example 1 to Example 4, and Review Example 7 (Y _0.9999 Ce _0.0001 ) ₃ Al ₅ O ₁₂ 0.01% 24.2156g 18.2090g 0.0037g

First, the raw materials are prepared.

For each sample, each raw material used shown in Table 1 was put into a plastic container (hereinafter referred to as a container) with a capacity of 1 L. At this time, each raw material and alumina beads (φ10 mm) were put into the container. The amount of alumina balls is an amount that fills approximately 1/3 of the volume of the container.

Then, an amount of pure water sufficient to soak the alumina beads was put into the container. Ball mill mixing was performed for 12 hours using a container rotating device (BALL MILL ANZ-51S manufactured by Nitto Scientific Co., Ltd.).

Furthermore, in Review Examples 1 to 7 and Examples 1 to 3, after ball milling and mixing, the slurry mixed raw materials were dried using a dryer. Specifically, the above-mentioned mixed raw materials were flowed onto a NAFLON (registered trademark) sheet (thickness 0.05 mm) laid to cover the inner wall of a metal barrel, and the mixed raw materials were put into a dryer set at 150°C. 6 hours to dry.

Thereafter, the dried mixed raw materials are recovered and granulated using a mortar and pestle. Specifically, the dried mixed raw materials are put into a mortar and ground to form mixed raw material powder. Furthermore, using a pipette, 0.18 mL of a binder solution (5 wt.% PVA (polyvinyl alcohol) solution) was added in small portions to 10 g of the mixed raw material powder, and kneaded using a pestle. That is, the binder liquid is dispersed throughout the mixed raw material powder. Thereafter, the mixed raw material powder was classified using a nylon mesh to obtain granulated powder. In addition, the opening diameter of the nylon mesh was set to 155 μm. In this way, raw materials for the powdery phosphor parts (YAG phosphor ceramics) of Review Examples 1 to 7 and Examples 1 to 3 were obtained. In addition, regarding Example 4, after ball milling and mixing, the slurry mixed raw materials were granulated by a spray drying device. More specifically, a slurry mixed raw material to which 0.5 wt.% of a binder (such as PVA (polyvinyl alcohol)) is added is granulated by a spray drying device. The average particle diameter of the obtained granulated powder was 45 μm. In this way, the raw material of the powdery phosphor part (YAG phosphor ceramic) of Example 4 was obtained.

Next, molding is performed.

First, the molding of Review Examples 1 to 7 and Examples 1 to 3 will be described. Initially, each raw material is molded into a cylindrical shape using a manual hydraulic press (manufactured by Riken Seiki Co., Ltd.) and a mold (φ13mm). The pressure applied to the sample during molding is 6 MPa. Next, a cold isostatic press (CIP (Cold Isostatic Press)) device is used to formally shape the raw material. Let the pressure during formal molding be 250MPa. In addition, the molded body after formal molding is subjected to a binder removal process (heating treatment in the atmosphere) for the purpose of removing the binder (polyvinyl alcohol) used during granulation. The conditions for the binder removal treatment are 500°C and 10 hours. Next, the molding of Example 4 will be described. The raw material of Example 4 was molded in the same manner as the raw materials of Review Example 1 to Review Example 7 and Examples 1 to 3, respectively, except for the following points. This point is based on the use of a mold (φ60mm) when using a manual hydraulic press (manufactured by Riken Seiki Co., Ltd.).

Furthermore, calcining is performed.

First, the calcination of Review Examples 1 to 7 and Examples 1 to 3 will be described. The molded bodies after the binder removal process are separately calcined using a vertical tubular atmosphere furnace. The calcination temperature was set to 1725°C. Let the calcination time be 4 hours. In addition, the calcining gas environment was a mixed gas of 97 vol.% nitrogen and 3 vol.% hydrogen. In addition, the flow rate of the mixed gas was set to 1 L/min. Next, the calcination in Example 4 will be described. The raw material of Example 4 after the binder removal treatment was calcined using a vertical tubular atmosphere furnace under the following conditions. The conditions are: the calcination temperature is 1700°C or more and 1725°C or less, the calcination time is 4 hours or more and 24 hours or less, and the calcination gas environment is a mixture of 95 vol.% or more and 97 vol.% or less nitrogen and 3 vol.% or more and 5 vol.% or less hydrogen. The mixed gas and the flow rate of the mixed gas are 1L/min or more and 5L/min or less.

Further, grinding is performed.

Each calcined sample was mirror-polished using a grinding device (DFD6340 manufactured by DISCO). The thickness after mirror polishing makes the sample with a Ce ³⁺ concentration of 0.08% fall into three levels: 225 μm (Example 1), 125 μm (Example 2), and 57 μm (Example 3). The sample with a Ce ³⁺ concentration of 0.03% was divided into three levels: 666 μm (Inspection Example 4), 400 μm (Inspection Example 5), and 300 μm (Inspection Example 6). The sample with a Ce ³⁺ concentration of 0.01% was divided into four levels: 705 μm (Example 1), 659 μm (Example 2), 400 μm (Example 3), 805 μm (Example 4), and 300 μm (Review Example 7). .

Finally, make the cut.

Each polished sample was cut using a cutting device (DAD3350 manufactured by DISCO). The samples of Review Examples 1 to 7 and Examples 1 to 3 were cut into squares with a side of 7 mm. The sample of Example 4 was cut into a square with a side of 10 mm. In this way, the fluorescent parts of Review Examples 1 to 7 and Examples 1 to 4 were produced.

The density of each produced fluorescent part was evaluated individually.

Here, the density of each fluorescent part is evaluated by Archimedes' method. Furthermore, assuming that the theoretical density of YAG was 4.55 g/cm ³ , the ratio of each fluorescent part to the theoretical density was calculated.

Samples with a Ce ³⁺ concentration of 0.08% (Review Examples 1 to 3), 0.03% samples (Review Examples 4 to 6), and 0.01% samples (Examples 1 to 4 and The densities of review example 7) are 4.450g/cm ³ , 4.476g/cm ³ and 4.512g/cm ³ respectively. In addition, the ratios to the theoretical density of samples with Ce ³⁺ concentrations of 0.08%, 0.03%, and 0.01% were 97.8%, 98.4%, and 99.2%, respectively.

In order to examine the influence of the Ce ³⁺ concentration and thickness of the fluorescent part on the angular dependence of the chromaticity of the output light, as shown in Figure 6, a spectrometer was used to measure the angle along the front direction (hereinafter referred to as the 0° direction) and The chromaticity of the output light output in the oblique direction (hereinafter referred to as the 45° direction). In addition, the output light output in the 0° direction and the 45° direction is equivalent to the above-mentioned light incident on the light guide. More specifically, the chromaticity of the output light was measured as follows.

Each cut sample was placed above the substrate member 10a, and phosphor elements of Review Examples 1 to 7 and Examples 1 to 4 were produced. From the substrate member 10a side, the phosphor elements of Review Examples 1 to 7 and Examples 1 to 4 were irradiated with laser light of 0.83W through the light source 2. The laser light irradiation spot area is 4mm ² . In addition, here, the light-transmitting base material 11 is a substrate made of sapphire; the samples of Review Examples 1 to 7 and Examples 1 to 3 are 7mm×7mm rectangular, and the sample of Example 4 is 10mm. ×10mm rectangle, thickness 500μm. Furthermore, the dielectric material multilayer film 12 is a film that transmits blue light and reflects light in a wavelength range of 480 nm to 780 nm with a reflectivity of 90% or more.

By irradiation with laser light, the angular dependence of the chromaticity of the output light outputted from the phosphor elements of Test Examples 1 to 7 and Examples 1 to 4 was measured. These output lights were measured using an integrating sphere (manufactured by Niem Corporation) and a multi-channel spectrometer (MCPD-7000, manufactured by Otsuka Electronics Co., Ltd.). In addition, here, no light reflecting portion is provided in each phosphor element. However, the inventor speculates that the chromaticity of the output light and the angle dependence of the chromaticity of the output light are the same as when the light reflecting portion is provided.

FIG. 7 is a graph showing the angle dependence of the chromaticity of the output light of the phosphor elements of Review Examples 1 to 3. FIG.

FIG. 8 is a graph showing the angle dependence of the chromaticity of the output light of the phosphor elements of Review Examples 4 to 6. FIG.

9 is a graph showing the angle dependence of the chromaticity of the output light of the phosphor elements of Examples 1 to 4 and Review Example 7.

In addition, xy chromaticity diagrams are shown in FIGS. 7 to 9 , and the xy chromaticity diagrams respectively show the chromaticity of the output light of the phosphor element in the 0° direction and the 45° direction. In Figures 7 to 9, a chain of dots in a rectangle representing a part of the xy chromaticity diagram is enlarged and displayed.

In addition, FIGS. 7 to 9 show rectangular dotted lines; this dotted line shows the allowable chromaticity range when a light source module equipped with a phosphor element is used, for example, in an endoscope. When this light source module is used in an endoscope, both the output light in the 0° direction and the output light in the 45° direction are used as light for the endoscope. Therefore, it is judged that by making both the chromaticity in the 0° direction and the chromaticity in the 45° direction converge within this chromaticity range (rectangular dotted line), the light source module can be used as a light-emitting device for endoscopes. . Furthermore, if the difference between the chromaticity of the output light output from the fluorescent part in the 0° direction and the chromaticity of the 45° direction is smaller (that is, the angle dependence of the chromaticity is smaller), the output light from the endoscope can be The angle dependence of the chromaticity of light is small. Therefore, a light source module including a phosphor element with small angular dependence of the chromaticity of the output light can be said to have higher performance as a light-emitting device for endoscopes.

In addition, Table 2 is a table showing the xy coordinates of the chromaticity of the output light of the phosphor elements of Review Examples 1 to 3. Table 3 is a table showing the xy coordinates of the chromaticity of the output light of the phosphor elements of Review Examples 4 to 6. Table 4 is a table showing the xy coordinates of the chromaticity of the output light of the phosphor elements of Examples 1 to 4 and Review Example 7.

[Table 2] Chroma Review example 1 0° direction Review example 1 45° direction Review example 2 0° direction Review example 2 45° direction Review example 3 0° direction Review example 3 45° direction x 0.39100 0.39300 0.31200 0.35100 0.18600 0.28600 y 0.52900 0.53300 0.36800 0.44900 0.09600 0.31100

[table 3] Chroma Review example 4 0° direction Review example 4 45° direction Review example 5 0° direction Review example 5 45° direction Review example 6 0° direction Review example 6 45° direction x 0.40400 0.40500 0.38039 0.38062 0.35200 0.35827 y 0.55600 0.55700 0.51569 0.51677 0.45693 0.47020

[Table 4] Chroma Example 1 0° direction Example 1 45° direction Example 2 0° direction Example 2 45° direction Example 3 0° direction Example 3 45° direction Example 4 0° direction Example 4 45° direction Review example 7 0° direction Review example 7 45° direction x 0.36400 0.36500 0.36100 0.36200 0.30851 0.31051 0.35999 0.36047 0.27464 0.28118 y 0.48300 0.48500 0.47700 0.47900 0.36660 0.37170 0.49309 0.49522 0.29282 0.30864

First, using FIG. 7 , the phosphor elements of Review Examples 1 to 3 in which the Ce ³⁺ concentration of the fluorescent part is the highest concentration of 0.08% will be described. In Figure 7, only the phosphor element of Example 2 was examined, and the chromaticity in the 0° direction and the chromaticity in the 45° direction converged within the chromaticity range (rectangular dotted line). However, compared to Review Example 2, in Review Example 1 in which the thickness of the fluorescent part is increased by 100 μm, the chromaticity in the 0° direction and the chromaticity in the 45° direction do not converge within the chromaticity range. Similarly, in Review Example 3 in which the thickness of the fluorescent part was reduced by 68 μm compared to Review Example 2, the chromaticity in the 0° direction did not converge within the chromaticity range.

In this way, when the Ce ³⁺ concentration of the fluorescent part is the highest concentration of 0.08%, even if the thickness of the fluorescent part is changed by about 100 μm, it is still impossible to achieve both the chromaticity in the 0° direction and the chromaticity in the 45° direction. Converged in the chromatic range.

Furthermore, in the phosphor element of Review Example 2, it was also clearly found that the difference between the chromaticity in the 0° direction and the chromaticity in the 45° direction was very large.

Next, using FIG. 8 , the phosphor elements of Review Examples 4 to 6 in which the Ce ³⁺ concentration of the fluorescent part is a high concentration of 0.03% will be described.

In Figure 8, only the phosphor element of Example 6 was examined, and the chromaticity in the 0° direction and the chromaticity in the 45° direction converged within the chromaticity range (rectangular dotted line). However, compared to Review Example 6, in Review Example 5 in which the thickness of the fluorescent part is increased by 100 μm, and in Review Example 4 in which the thickness of the fluorescent part is increased by 366 μm, the chromaticity in the 0° direction and the color in the 45° direction are The degree does not converge within the chromaticity range.

In this way, when the Ce ³⁺ concentration of the fluorescent part is as high as 0.03%, if the thickness of the fluorescent part changes by more than 100 μm, both the chromaticity in the 0° direction and the chromaticity in the 45° direction cannot be converged. in the chromatic range.

Furthermore, in the phosphor element of Review Example 6, it was also clearly found that the difference between the chromaticity in the 0° direction and the chromaticity in the 45° direction was very large.

Furthermore, the phosphor elements of Examples 1 to 4 and Test Example 7 in which the Ce ³⁺ concentration of the fluorescent part is as low as 0.01% will be described using FIG. 9 .

As shown in FIG. 9 , for all the phosphor elements of Examples 1 to 4, the chromaticity in the 0° direction and the chromaticity in the 45° direction converge within the chromaticity range (rectangular dotted line). Different from Review Examples 1 to 6 shown in Figures 7 and 8, in the phosphor elements of Examples 1 to 4, even if the thickness of the phosphor portion is significantly changed from 400 nm to 805 nm, the colors in the two directions are The degree still converges within the chromaticity range. That is, it is shown that “in the phosphor elements of Examples 1 to 4 in which the Ce ³⁺ concentration of the phosphor part is as low as 0.01%, even if the thickness of the phosphor part changes, the chromaticity in the two directions remains the same. Not easy to change".

In addition, it is clear that in the phosphor element of Review Example 7, the chromaticity in the 0° direction and the chromaticity in the 45° direction converge within the chromaticity range (dashed line of the rectangle), but the chromaticity in the 0° direction is different from that of 45°. The difference in chromaticity in the ° direction is very large. On the other hand, it is shown that "in all the phosphor elements of Examples 1 to 4, the difference between the chromaticity in the 0° direction and the chromaticity in the 45° direction is very small, that is, the angle dependence of the chromaticity is small." .

Here, regarding the angular dependence of chromaticity, a comparison is made between the phosphor element of Review Example 6 (refer to Figure 8) and the phosphor element of Example 2 (refer to Figure 9), which exhibit the same level of chromaticity. . The angular dependence of the chromaticity of the phosphor element of Example 2 is smaller than the angular dependence of the chromaticity of the phosphor element of Examination Example 6. That is, it is shown that "within the same range of chromaticity, the phosphor element of Example 2, which has a very low Ce ³⁺ concentration in the phosphor part, has smaller angle dependence of chromaticity."

In this way, in Examples 1 to 4, by setting the Ce ³⁺ concentration to 0.01% and the thickness to 350 μm or more and 820 μm or less, the angular dependence of the chromaticity of the output light is better than that in Review Examples 1 to 7. Small phosphor components. This principle will be explained using Figure 10A.

Figure 10A is a diagram illustrating the effects of Ce ³⁺ concentration and thickness on excitation light and fluorescence.

In FIG. 10A , the fluorescent part after changing the Ce ³⁺ concentration and thickness, and the excitation light (blue light) and fluorescent light (yellow light) reaching the fluorescent part are illustrated. The ratio of the lengths of the solid arrows representing blue light and the dashed arrows representing yellow light shows the ratio of the blue light intensity to the yellow light intensity of the output light.

In Figure 10A, the fluorescent part with high Ce ³⁺ concentration and thick thickness is equivalent to review example 4; the fluorescent part with high Ce ³⁺ concentration and thin thickness is equivalent to review example 6. In addition, the fluorescent part with low Ce ³⁺ concentration and thick thickness corresponds to Example 2; the fluorescent part with low Ce ³⁺ concentration and thin thickness corresponds to Review Example 7.

In addition, even if the fluorescent part has the same thickness, the length of the dotted arrow (yellow light) is longer when the Ce ³⁺ concentration is higher, that is, the yellow light intensity of the output light is greater. This is because those with a higher Ce ³⁺ concentration have a higher absorption rate of blue light and are easier to convert into yellow light. Similarly, even for fluorescent parts with the same Ce ³⁺ concentration, if the thickness is thicker, the length of the dotted arrow (yellow light) is longer, that is, the yellow light intensity of the output light is greater. This is because thicker ones are more likely to absorb blue light and convert it into yellow light.

In Review Example 4, in the 0° direction and the 45° direction, the difference in the ratio between the length of the solid arrow (blue light) and the length of the dotted arrow (yellow light) is small, so the angular dependence of the chromaticity is small. However, due to the high intensity of yellow light, the output light is almost yellow light. As shown in Figure 8, the chromaticity in the 0° direction and the chromaticity in the 45° direction do not converge within the chromaticity range.

In Review Example 6, compared to Review Example 4, the intensity of yellow light is lower in the 0° direction and the 45° direction, so the output light is close to white light. However, the ratio of the length of the solid arrow (blue light) to the length of the dotted arrow (yellow light) is different in the 0° direction and the 45° direction, so the angle dependence of chromaticity is large.

In Example 2, compared to Review Example 6, the intensity of yellow light is lower in the 0° direction and the 45° direction, so the output light is close to white light. Furthermore, in the 0° direction and the 45° direction, the difference in the ratio between the length of the solid arrow (blue light) and the length of the dotted arrow (yellow light) is small, so the angular dependence of the chromaticity is small.

In Review Example 7, compared to Review Example 6, the intensity of blue light is higher in the 0° direction and the 45° direction, so the output light becomes white light containing a large amount of blue light. However, the ratio of the length of the solid arrow (blue light) to the length of the dotted arrow (yellow light) is different in the 0° direction and the 45° direction, so the angle dependence of chromaticity is large.

In this way, by controlling both the Ce ³⁺ concentration and the thickness of the fluorescent part, in Examples 1 to 4, compared with Review Examples 1 to 7, angle dependence of the chromaticity of the output light was achieved. Small phosphor components.

As shown in Figures 7 to 9, it is also clear that in Review Examples 1 to 7, it is difficult to make both the chromaticity in the 0° direction and the chromaticity in the 45° direction converge within the chromaticity range and the color in the 0° direction. The difference between the chromaticity and the chromaticity in the 45° direction is very large. Especially as shown in Figures 7 and 8, in the range where the Ce ³⁺ concentration is very high, there is a significant change in the chromaticity of the output light due to a thickness change of about 100 μm. The chromaticity in the 0° direction is different from the chromaticity in the 45° direction. The difference in chromaticity is very large and other issues.

Regarding these problems, after repeated careful review, the inventors of the present case found that according to the mechanism shown in Figure 10A, the chromaticity in the 0° direction and the 45° direction is achieved to converge within the chromaticity range, and the chromaticity is angle-dependent. The phosphor elements of Examples 1 to 4 have low resistance.

As mentioned above, the phosphor elements of Examples 1 to 4 are equivalent to the phosphor element 1 of this embodiment from the viewpoint of Ce ³⁺ concentration and thickness. Therefore, like the phosphor elements of Examples 1 to 4, in the phosphor element 1 of this embodiment, the chromaticity in the 0° direction and the 45° direction converges within the chromaticity range, and the angle of the chromaticity Little dependence on phosphor components.

[Influence of the thickness and surface roughness of the fluorescent part] Here, the influence of the thickness and surface roughness of the phosphor part 21 (ie, YAG phosphor ceramic) on the characteristics of the phosphor element 1 will be further described. First, the influence of the thickness of the fluorescent part 21 is examined.

In order to examine the influence of the thickness of the fluorescent part 21, 9 types of samples (9 types of phosphor elements) were produced. These 9 types of samples have different thicknesses of the fluorescent part. Six types of samples among the nine types of samples have the same structure as the phosphor element 1 shown in FIG. 1 , that is, the thickness of the fluorescent portion 21 of these six types of samples is 350 μm or more and 820 μm or less. Specifically, the designed thicknesses of the fluorescent parts 21 of the six samples are 575 μm, 641 μm, 680 μm, 747 μm, 753 μm, and 802 μm respectively. In the following, the sample with the designed thickness of the fluorescent part 21 of 575 μm is called the sample 575 μm, the sample with the designed thickness of 641 μm is called the sample 641 μm, and the sample with the designed thickness of 680 μm is called the sample. 680 μm, a sample with a design thickness of 747 μm is called a sample 747 μm, a sample with a design thickness of 753 μm is called a sample 753 μm, and a sample with a design thickness of 802 μm is called a sample 802 μm. In addition, the remaining three types of samples among the nine types of samples have the same structure as the phosphor element 1 shown in FIG. 1 except that the thickness of the phosphor part is different. Here, these three types of samples The thickness of the fluorescent part is larger than 820μm. Specifically, the design thicknesses of the fluorescent parts of the three samples are 826 μm, 873 μm, and 918 μm. In the following, the sample with a designed thickness of the phosphor part of 826 μm is called sample 826 μm, the sample with a designed thickness of 873 μm is called sample 873 μm, and the sample with a designed thickness of 918 μm is called sample 918 μm. situation.

Here, the manufacturing methods of these 9 types of samples are explained. First, YAG phosphor ceramics used in the phosphor parts of each of the nine samples were produced. The target composition of the YAG phosphor ceramic used in the fluorescent part is the same as the YAG phosphor ceramic used in the phosphor elements of Examples 1 to 4 and Review Example 7. In addition, the YAG phosphor ceramic used in the phosphor part was produced by the same method as the YAG phosphor ceramic used in the phosphor element of Example 4 until the calcining step (calcining step) was performed. The YAG phosphor ceramic that has been subjected to the calcination step is then processed into a shape of 0.8 mm in length, 0.8 mm in width, and 1 mm in height using a grinding device (DFD6340 made by DISCO) and a cutting device (DAD3350 made by DISCO). above. Next, a mold (φ13 mm) was prepared, and Al ₂ O ₃ powder with an average primary particle diameter of 0.28 μm was put into the mold. Thereafter, the shape-processed YAG phosphor ceramic was placed in the Al ₂ O ₃ powder filled in the mold. In addition, at this time, the shaped YAG phosphor ceramic was placed near the center of the Al ₂ O ₃ powder filled in the mold so that the height direction was approximately perpendicular to the ground. Then, it is molded into a roughly cylindrical shape using a manual hydraulic press (manufactured by Riken Seiki Co., Ltd.). The pressure applied to the sample during molding was set to 6 MPa. Next, formal molding is carried out using a cold isostatic press (CIP) device. Let the pressure during formal molding be 250MPa. In this way, the shape-processed YAG phosphor ceramic was placed in the Al ₂ O ₃ powder to produce a composite molded body. The produced composite molded body is calcined using a box-type atmospheric atmosphere furnace. The calcining temperature is 1200°C to 1300°C. Let the calcination time be 2 hours. In this way, a composite ceramic composed of the shape-processed YAG phosphor ceramic and the Al ₂ O ₃ ceramic was produced. The produced composite ceramics were changed into nine thicknesses using a grinding device (DFD6340 manufactured by DISCO). The nine types of composite ceramics with changed thicknesses were each processed into a square shape with a length of 7.0 mm and a width of 7.0 mm using a cutting device (DAD3350 manufactured by DISCO) with the YAG phosphor ceramic placed approximately in the center. . Then, the shape-processed composite ceramics were placed on a light-transmitting substrate with a dielectric material multilayer film and an anti-reflective film, respectively, to prepare the above nine types of samples. In addition, sample 575 μm, sample 641 μm, sample 680 μm, sample 747 μm, sample 753 μm, and sample 802 μm are phosphor elements having the same structure as the phosphor element 1 shown in FIG. 1 , that is, This is a sample corresponding to the phosphor element 1.

These nine types of samples are samples in which the thickness of the fluorescent part (thickness in the vertical direction in Figure 1) was changed. The total luminous flux of the output light outputted from each of the nine types of samples was measured.

FIG. 10B is a graph showing the total luminous flux of the output light of nine samples with different thicknesses of the fluorescent parts. Here, the total luminous flux of the output light of each of the nine samples was measured when the power input to emit the excitation light was 5.2 W. Table 5 is a table showing the thickness of the fluorescent part and the total luminous flux of the output light of nine types of samples. [table 5] Fluorescent part thickness (μm) 575 641 680 747 753 802 826 873 918 Total luminous flux (lm) 1262 1246 1275 1288 1274 1275 1219 1258 1373 As shown in Figure 10B and Table 5, it is clear that the total luminous flux of the output light output from the nine types of samples is all above 930 lm, more specifically, all is above 1200 lm. Furthermore, it was shown that the total luminous flux tends to become higher as the thickness of the fluorescent part becomes thicker.

In addition, when the light source module 100 including the phosphor element 1 of this embodiment is used in an endoscope, for example, the total luminous flux of the output light output from the phosphor element 1 is required to be 930 lm or more. The six types of samples (i.e., sample 575 μm, sample 641 μm, sample 680 μm, sample 747 μm, sample 753 μm, and sample 802 μm) with a thickness of 350 μm or more and 820 μm or less of the fluorescent part 21 are equivalent to the present invention. Samples of the phosphor element 1 of the embodiment; the total luminous flux of the output light of these six samples is all 930 lm or more. Therefore, the phosphor element 1 of this embodiment (each of the six types of samples) is an element whose total luminous flux of output light is high enough to be usable in an endoscope. In addition, from the perspective of the total luminous flux, the three samples with the thickness of the fluorescent part larger than 820 μm are also samples in which the total luminous flux of the output light is high enough to be used in an endoscope. In addition, it has been shown with reference to FIG. 9 and others that the phosphor element 1 of this embodiment is a phosphor element in which the chromaticity in the 0° direction and the 45° direction converges within the chromaticity range, and the angular dependence of the chromaticity is small. Therefore, in this embodiment, by setting the Ce ³⁺ concentration to 0.01% and the thickness to 350 μm or more and 820 μm or less, a phosphor element with a small angle dependence of the chromaticity of the output light and a high total luminous flux of the output light is realized. 1.

Furthermore, the color temperature of the output light output from each of the nine types of samples was measured. FIG. 10C is a graph showing the color temperatures of nine samples with different thicknesses of the fluorescent parts. In addition, in FIG. 10C , the approximate straight line calculated by the least squares method based on the color temperatures of the nine samples is represented by a one-dot chain line. Table 6 is a table showing the thickness of the fluorescent part and the color temperature of the output light of nine types of samples. [Table 6] Fluorescent part thickness (μm) 575 641 680 747 753 802 826 873 918 Color temperature(K) 6606 6144 5910 5709 5557 5481 5422 5245 4995 As shown in Figure 10C and Table 6, it is clear that the color temperatures of the output light output from the nine types of samples are all above 4500K and below 7000K. Furthermore, it was shown that the color temperature tends to become smaller as the thickness of the fluorescent part becomes thicker.

When the light source module 100 including the phosphor element 1 of this embodiment is used as an endoscope, for example, the color temperature of the output light output from the phosphor element 1 is preferably 3500K or more and 15000K or less, more preferably 4500K. Above 7000K and below, it should further be in the range above 5050K and below 5810K. The three types of samples (namely, sample 747 μm, sample 753 μm, and sample 802 μm) in which the thickness of the fluorescent part 21 is 747 μm or more and 802 μm or less are, as described above, equivalent to the phosphor element 1 of this embodiment. The color temperatures of the output light of these three samples are all above 5050K and below 5810K, that is, they are all values within the above-mentioned more suitable range. In addition, calculated using the approximate straight line in FIG. 10C , if the thickness of the fluorescent part is in the range of 726 μm or more and 902 μm or less, it is estimated that the color temperature is a value within the above-mentioned more suitable range. In addition, the phenomenon that the color temperature changes due to the change in the thickness of the fluorescent part is as explained in FIG. 10A and so on. In this way, in the phosphor element 1 of this embodiment (for example, these three types of samples), by setting the thickness of the phosphor part 21 to 726 μm or more and 820 μm or less, the color temperature of the output light can be in a more appropriate range, and as follows As shown in Figure 9, the angle dependence of the chromaticity of the output light is small. Therefore, the phosphor element 1 of this embodiment can be more easily used in an endoscope. In addition, the thickness of the fluorescent part 21 is not limited to the above-mentioned form. It may be 750 μm or more and 820 μm or less, it may be 770 μm or more and 820 μm or less, or it may be 790 μm or more and 820 μm or less.

Next, the influence of the surface roughness of the fluorescent part 21 is examined.

In order to examine the influence of the surface roughness of the fluorescent part 21, four types of samples having the same structure as the fluorescent element 1 shown in FIG. 1 were produced. These four types of samples were obtained by changing the surface roughness of the light incident surface 211 and the light exit surface 212 of the fluorescent part 21 respectively. Here, the manufacturing methods of these four types of samples are explained. First, YAG phosphor ceramics used in the phosphor portions 21 of each of the four types of samples were produced. The target composition of the YAG phosphor ceramic used in the phosphor part 21 is the same as the YAG phosphor ceramic used in the phosphor elements of Examples 1 to 4 and Review Example 7. In addition, the YAG phosphor ceramic used in the phosphor part 21 was used in the phosphor elements of Examples 1 to 3 and Review Example 7 until the calcining step (calcining step) was performed. Fluorescent ceramics are made in the same way. Regarding the steps after the calcination step of these four types of samples, they are produced through the same steps as the above-mentioned nine types of samples, except that the particle size of the grinding wheel is changed in the grinding step of the composite ceramics. Made in the same way. Then, the total luminous flux of the output light outputted from each of the four types of samples was measured.

FIG. 10D is a graph showing the total luminous flux of the output light of four types of samples with different surface roughness of the fluorescent part 21 . Here, the total luminous flux of the output light of each of the four types of samples was measured when the power input to emit the excitation light was 5.2 W.

In addition, the surface roughness of each of the four types of samples was made different by grinding as follows. A sample (hereinafter referred to as sample (1400/8000)) was produced in which the light exit surface 212 was ground with a grinding wheel grit of No. 1400, and the light incident surface 211 was ground with a grinding wheel grit of No. 8000. A sample (hereinafter referred to as sample (600/600)) was produced in which the light exit surface 212 was ground with a grinding wheel grit of No. 600, and the light incident surface 211 was ground with a grinding wheel grit of No. 600. A sample (hereinafter referred to as sample (1400/1400)) was produced in which the light exit surface 212 was ground with a grinding wheel grit of No. 1400, and the light incident surface 211 was ground with a grinding wheel grit of No. 1400. A sample (hereinafter referred to as sample (4000/4000)) was produced in which the light exit surface 212 was ground with a grinding wheel grit of No. 4000, and the light incident surface 211 was ground with a grinding wheel grit of No. 4000.

In addition, two samples (1400/8000), two samples (600/600), two samples (1400/1400), and three samples (4000/4000) were produced.

In addition, the horizontal axis of FIG. 10D shows the grit size of the grinding wheel used for grinding the light exit surface 212 of each of the four samples. Further, in FIG. 10D , the correlation between the grinding wheel grain size and the surface roughness (more specifically, the arithmetic mean roughness Ra) is shown. That is, the Ra of each of the light exit surface 212 and the light entrance surface 211 of the sample (600/600) is 145 nm. The Ra of each of the light exit surface 212 and the light entrance surface 211 of the sample (1400/1400) is 137 nm. The Ra of the light exit surface 212 of the sample (1400/8000) is 137 nm. In addition, the Ra of the light incident surface 211 of the sample (1400/8000) is 11 nm. The Ra of each of the light exit surface 212 and the light entrance surface 211 of the sample (4000/4000) is 20 nm.

In addition, the sample (1400/8000) serves as a reference sample and has a very high total luminous flux. For other samples, it is also appropriate to obtain the same total luminous flux as the sample (1400/8000).

The average of the total luminous flux of 2 samples (600/600), the average of the total luminous flux of 2 samples (1400/1400), and the average of the total luminous flux of 3 samples (4000/4000), respectively The same as the average of the total luminous flux of the two samples (1400/8000).

As shown in FIG. 10D , by setting the Ra of the light incident surface 211 to 20 nm or more, the total luminous flux can be obtained to the same extent as that of the reference sample (1400/8000). In addition, from the review by the present inventors, it became clear that by setting the Ra of the light incident surface 211 to 500 nm or less, the same level of total luminous flux as that of the reference sample (1400/8000) can be obtained. Furthermore, it is also clear from FIG. 10D that by setting the Ra of the light incident surface 211 to 20 nm or more and 145 nm or less, the same total luminous flux as that of the reference sample (1400/8000) can be obtained. In addition, the Ra of the light incident surface 211 of the reference sample (1400/8000) is 11 nm. Compared with the sample (1400/8000) where the Ra of the light incident surface 211 is 11 nm, the number of steps or the cost for manufacturing the sample where the Ra of the light incident surface 211 is 20 nm or more is reduced. That is, it is possible to realize a phosphor element 1 that outputs light at a low cost and has a total luminous flux equivalent to that of the reference sample (1400/8000).

[Characteristics of the light reflecting part] Furthermore, the light reflection part 22 is demonstrated in more detail. Here, the manufacturing method and physical properties of the light reflecting portion 22 will be described.

In [Characteristics of the light reflecting portion], three samples of the light reflecting portion 22 were produced. Here, three samples in which the calcination temperatures described below were changed were produced.

As the raw material for each sample, Al ₂ O ₃ powder having an α-type crystal system with an average particle diameter of 0.2 μm was used.

This Al ₂ O ₃ powder was molded into a cylindrical shape using a manual hydraulic press (manufactured by Riken Seiki Co., Ltd.) and a mold (φ13 mm). When Al ₂ O ₃ powder is molded, the pressure applied to each sample is 6 MPa. Then, the molded samples were each formally formed using a cold pressure equalizing and pressing device. During formal molding, the pressure applied to each sample was 250MPa. In addition, no adhesive is used during molding and formal forming. In this way, a molded body of the raw material of the light reflecting portion 22 is obtained.

Furthermore, the molded body is calcined in an atmospheric electric furnace. The calcination temperature is in the range of about 1100°C to about 1500°C. By changing the calcination temperature, three samples with different densities were produced.

Next, the density of each calcined sample was evaluated by Archimedes' method. In addition, the theoretical density of Al ₂ O ₃ was set to 3.95 g/cm ³ , and the ratio of the sample to the theoretical density was calculated.

The densities of each of the three samples are 3.230g/cm ³ , 3.788g/cm ³ , and 3.950g/cm ³ . In addition, the ratios of the three samples to the theoretical density were 81.1%, 95.0%, and 100%. In addition, below, the sample with a density of 3.230 g/cm ³ will be called a first sample, a sample with a density of 3.788 g/cm ³ will be called a second sample, and a sample with a density of 3.950 g/cm ³ will be called the first sample. The sample is called the third sample. In addition, the higher the calcination temperature, the higher the density of the sample, that is, the higher the ratio of the sample to the theoretical density.

As mentioned above, the density of the light reflective portion 22 in this embodiment (that is, the density of the light reflective ceramic) only needs to be 98% or less of the theoretical density. Therefore, the first sample and the second sample correspond to the light reflective portion 22 . As mentioned above, the main component of the light reflective part 22 is light reflective ceramics, so the main components of the first and second samples corresponding to the light reflective part 22 are also light reflective ceramics.

Furthermore, the light reflectivity in the visible light range was measured for three samples of the light reflecting portion 22 .

FIG. 11 is a graph showing relative values of light reflectance of the first to third samples. In addition, FIG. 11 shows the first and second samples corresponding to the light reflecting portion 22 and the third sample not corresponding to the light reflecting portion 22 .

In addition, the relative value of the light reflectance was measured as follows. The visible light reflectance (relative value of light reflectance) of each sample was evaluated with a fluorescence spectrometer (JASCO Corporation, FP-6500). Here, the ratio of the reflection intensity of light in the wavelength range of 400 nm to 800 nm of each sample to the reflection intensity of light in the wavelength range of 400 nm to 800 nm of the plate-shaped barium sulfate member was measured as the light reflectance. Relative value. That is, the relative value of light reflectivity refers to the relative reflectivity.

As shown in Figure 11, it is shown that the sample with a lower ratio relative to the theoretical density has a higher relative value of light reflectance. As described above, in the phosphor element 1 of this embodiment, the light traveling along the lateral side among the output light (white light) emitted from the fluorescent part 21 is reflected by the light reflecting part 22 and returns to the fluorescent part 21. Emitted from the fluorescent part 21 to the outside. Therefore, the higher the relative value of the light reflectivity of the light reflecting portion 22 is, the more the output light output from the phosphor element 1 is increased.

In this embodiment, the density of the sample corresponding to the light reflective portion 22 (that is, the density of the light reflective ceramic) is preferably 98% or less of the theoretical density, more preferably 95% or less, and further preferably 90% or less. By setting the density of the light-reflective ceramics, which is the main component of the light-reflecting portion 22, within the above range, the relative value of the light reflectance can be increased.

Next, the surface conditions of the three samples of the light reflecting part 22 were observed with a scanning electron microscope. The observation magnification was set to 5000 times.

Fig. 12 is a diagram showing images showing the surface conditions of the first to third samples. In addition, FIG. 12 shows the first and second samples corresponding to the light reflecting portion 22 and the third sample not corresponding to the light reflecting portion 22 .

As shown in Figure 12, the sample with a lower ratio to the theoretical density, that is, the sample with a lower calcination temperature, has smaller voids in the sample. In particular, the size of the gaps corresponding to the first and second samples of the light reflecting portion 22 is 100 nm or more and 2000 nm or less. As described above, since the main component of the first and second samples corresponding to the light reflective portion 22 is the light reflective ceramic, the size of the voids in the light reflective ceramic of this embodiment is 100 nm or more and 2000 nm or less.

By setting the size of the gap, that is, the size of the light scattering portion 23, within this range, the output light (white light) emitted from the fluorescent portion 21 can be reflected by light scattering, as shown in FIG. 11 , which can improve the relative value of light reflectivity.

In addition, the size of the voids in the light-reflective ceramics of this embodiment is not limited to the above-mentioned embodiment. The average size of the voids is preferably not less than 100 nm and not more than 10,000 nm, more preferably not less than 100 nm and not more than 5,000 nm, further preferably not less than 100 nm and not more than 2,000 nm. If the average size of the voids is within the above range, the output light (white light) emitted from the fluorescent part 21 can be reflected by light scattering, so that the relative value of the light reflectance can be improved.

[Review of the influence of the light reflection part on the output light] Furthermore, the influence of the density of the light reflection portion 22 (that is, the density of the light reflective ceramic) of the present embodiment on the light-emitting area of the phosphor element 1 and the total luminous flux of the output light is examined. First, the impact on the light-emitting area is explained.

In [Examination of the Influence of the Light Reflection Part on Output Light], three samples having the same structure as the phosphor element 1 shown in FIG. 1 were produced. These three samples are samples in which the density of the light reflecting portion 22 was changed respectively.

FIG. 13 is a diagram showing the luminescence images of three samples having different densities of the light reflecting portions 22 . In addition, FIG. 13 shows the luminescence image when there is no aperture (Aperture) when capturing the luminescence image, and the luminescence image when there is the aperture. In addition, similar to Figure 4, in the luminescence image, the distribution of brightness when excitation light is irradiated is displayed as a gradient. The lighter the color, the higher the brightness, and the darker the color, the lower the brightness. In addition, in each of the six luminescence images, the brightness distribution of the (a)-(a) line is displayed as spectrum A, and the brightness distribution of the (b)-(b) line is displayed as spectrum B.

In addition, the three samples having different densities of the light reflecting portions 22 are specifically as follows.

For the three samples, the light reflecting part 22 was calcined at 1200°C, 1250°C and 1300°C respectively. By calcining at different calcining temperatures, three samples having different densities of the light reflecting portions 22 are produced.

The ratio of the light reflecting portion 22 to the theoretical density of the sample calcined at 1200° C. is approximately 89%, and this sample is hereinafter referred to as the sample (1200° C.). The ratio of the light reflecting portion 22 of the sample calcined at 1250° C. to the theoretical density is approximately 92%, and this sample is hereinafter referred to as the sample (1250° C.). The ratio of the light reflecting portion 22 of the sample calcined at 1300° C. to the theoretical density is approximately 95%, and this sample is hereinafter referred to as the sample (1300° C.).

As explained in Figure 11, if the calcination temperature is higher, that is, the ratio relative to the theoretical density is higher, the light reflectivity decreases. Among the three samples illustrated in Figure 13, the light reflectance also decreases in the order of sample (1200°C), sample (1250°C) and sample (1300°C). Therefore, as shown in Figure 13, the sample (1300°C), that is, the sample with a ratio of about 95% to the theoretical density, has lower light reflectivity, lower fluorescence and excitation light than the other two samples. Enter into the light reflecting part 22 . Therefore, the sample (1300°C) has a larger light-emitting area than the other two samples.

Furthermore, the degree of expansion of the light-emitting area will be described using FIG. 14 .

FIG. 14 is a graph showing the area of the fluorescent part 21 (fluorescent part area), the light emitting area, and the value obtained by dividing the light emitting area by the fluorescent part area of three samples having different densities of the light reflecting part 22. In addition, the value obtained by dividing the light-emitting area by the area of the fluorescent part is expressed as "light-emitting area/fluorescent part area". The fluorescent part area and the light-emitting area correspond to the left vertical axis, and the value obtained by dividing the light-emitting area by the fluorescent part area corresponds to the right vertical axis. Furthermore, FIG. 14 shows the correlation between the firing temperature of the light reflecting part 22 and the ratio to the theoretical density.

In each of the three samples, the light-emitting area is larger than the fluorescent area. However, the value obtained by dividing the luminous area by the area of the phosphor is the largest in the sample calcined at 1300°C (sample (1300°C)), and the sample showing the largest expansion of the luminous area is the sample (1300°C). ).

If the light reflectivity of the light reflecting portion 22 is low, the light-emitting area of the fluorescent portion 21 will be expanded. As a result, the output light incident on the light guide provided above the fluorescent element 1 will be reduced. That is, the utilization efficiency of the output light decreases.

Therefore, the higher the reflectivity of the light reflecting portion 22 is, the better, that is, the lower the density of the light reflecting portion 22 is, the better. For example, it is preferable that the density of the light reflective portion 22 (that is, the density of the light reflective ceramic) is 98% or less of the theoretical density. Furthermore, the density of the light reflective portion 22 (that is, the density of the light reflective ceramic) is more preferably 95% or less, further preferably 90% or less. With such a structure, the light reflectance of the light reflection part 22 can be improved, and the expansion of the light emitting area of the fluorescent part 21 can be suppressed. As a result, the output light incident on the light guide member provided above the phosphor element 1 is increased, and the phosphor element 1 with improved utilization efficiency of the output light is realized.

Next, the influence of the density of the light reflective portion 22 (that is, the density of the light reflective ceramic) on the total luminous flux of the output light of the phosphor element 1 will be described.

FIG. 15 is a diagram showing an example of the luminescence characteristics of three samples having different densities of light reflecting portions 22 .

The horizontal axis of FIG. 15 represents the power input (power input) in order to emit excitation light from the light source 2 . The vertical axis of Figure 15 represents the total luminous flux of the output light of each of the three samples. In the case of no opening (no AP), measure the total luminous flux of all output lights of each of the three samples. On the one hand, when there is an opening (AP), the total luminous flux of the output light passing through the opening (AP) among the output lights of each of the three samples is measured. In addition, the output light that has passed through the opening (AP) is also the output light that is incident on the light guide.

As shown in Figure 15, in the case of no opening (no AP), if the total luminous flux of the output light of each of the three samples is the same input power, it will be the same. However, in the case of openings (with AP), the total luminous flux of the sample (1300℃) is about 15% lower than the total luminous flux of the sample (1200℃) and the sample (1250℃) respectively. .

FIG. 16 is a diagram showing another example of the luminescence characteristics of three samples having different densities of the light reflecting portions 22 .

The horizontal axis of FIG. 16 represents the electric power input to emit excitation light from the light source 2 (input electric power). The vertical axis of FIG. 16 represents the ratio of the total luminous flux of the output light in the case where there is an opening (with AP) to the total luminous flux of the output light in the case where there is no opening (without AP) for each of the three samples.

As shown in Figure 16, in the sample (1300°C), the ratio of the total luminous flux of the output light in the case of the opening (with AP) to the total luminous flux of the output light in the case of no opening (without AP) is larger than that of the other cases. 2 samples were lower. That is, due to the opening (AP), the total luminous flux of the output light of the sample (1300°C) is greatly reduced compared with the other two samples. As shown in Figure 14, the sample (1300°C) has a larger luminous area than the other two samples. Therefore, the proportion of the output light that cannot pass through the opening (AP) among the output light of the sample (1300°C) becomes larger than that of the other two samples. Therefore, due to the provision of the opening (AP), compared with the other two samples, the total luminous flux of the output light of the sample (1300°C) passing through the opening (AP) is greatly reduced. For example, when the input power is 5.2W, compared with the other two samples, at the sample (1300°C), the total luminous flux of the output light in the case of having an opening (with AP) is relative to that of the case without opening (without AP). The ratio of the output light to the total luminous flux of the situation is reduced by 4%.

As shown in FIGS. 15 and 16 , if the ratio of the light reflecting portion 22 to the theoretical density is lower, that is, if the light reflectivity of the light reflecting portion 22 is higher, the output light passing through the opening (AP) can be reduced. As the ratio increases, the output light incident on the light guide increases. That is, the phosphor element 1 with high output light utilization efficiency can be realized.

[Inspection of the light reflectivity of the light reflecting part] In [Inspection of the light reflectivity of the light reflecting part], ten samples of the light reflecting part 22 were further produced. In addition, these 10 samples are different from the first to third samples mentioned above, but they are the same except for the Al ₂ O ₃ powder used as the raw material and the calcination temperature. How to make it.

These 10 samples are classified into 2 types of samples. These two types of samples were produced using different types of Al ₂ O ₃ powders. One of the two types of samples includes 5 samples, and these 5 samples are called the 4th to 8th samples for identification. The other type of sample among the two types of samples includes 5 samples. For the purpose of identification, these 5 samples are called the 9th to 13th samples.

In addition, in the 4th to 8th samples, TM-5D (Daimei Chemical Industry Co., Ltd.) was used as the Al ₂ O ₃ powder; in the 9th to 13th samples, AKP-700 (Sumitomo Chemical Co., Ltd.) was used as the Al powder. ₂ O ₃ powder. The average primary particle diameter of TM-5D is 0.2μm, and the average primary particle diameter of AKP-700 is less than 0.17μm.

Furthermore, the calcination temperature when preparing the 4th to 13th samples is demonstrated. The 4th and 9th samples were calcined at 1150°C respectively. The 5th and 10th samples were calcined at 1200°C respectively. The 6th and 11th samples were calcined at 1250°C respectively. The 7th and 12th samples were calcined at 1300°C respectively. The 8th and 13th samples were calcined at 1400°C respectively.

FIG. 17 is a graph showing the relative values of light reflectance of the fourth to eighth samples. Fig. 18 is a graph showing the relative values of light reflectance of the ninth to thirteenth samples. The method for measuring the relative value of light reflectance is the same as for the first to third samples. In addition, in FIGS. 17 and 18 , the reflectance of the barium sulfate member for each measurement wavelength is set to 1, and the relative values of the light reflectance of the fourth to thirteenth samples are shown. In addition, in Figures 17 and 18, the calcination temperature is shown in parentheses.

As shown in Figures 17 and 18, in any one of the fourth to thirteenth samples, compared with the long wavelength range (for example, the wavelength range of 500 nm to 800 nm), the short wavelength range (for example, 400 nm to 450 nm) is (wavelength range), the relative value of light reflectivity decreases. However, in the 4th to 7th samples, and the 9th and 10th samples, the decrease in the relative value of the light reflectance in the short wavelength range is suppressed, that is, the same value is displayed in the entire visible light range. Relative value of degree of light reflectance.

In this way, it is preferable that the relative value of the reflectance of light of short wavelength is high relative to the relative value of reflectance of light of long wavelength. Specifically, when the relative value of the long-wavelength light reflectance (that is, the relative reflectance) is 100%, it is preferable to set the relative value of the short-wavelength light reflectance (that is, the relative reflectance) to 95% or more.

As an example, long wavelength is a wavelength ranging from 500nm to 800nm; short wavelength is a longer wavelength and shorter wavelength, which is a wavelength ranging from 400nm to 450nm. In this case, for example, the long wavelength is 700nm and the short wavelength is 400nm. When the relative value of the light reflectance of the long wavelength (700nm) is 100%, the relative value of the light reflectance of the short wavelength (400nm) is above 95. In the fourth sample, the relative values of the light reflectance of long wavelength (700nm) and short wavelength (400nm) are 1.01 and 0.98 respectively. If the relative value of the long wavelength (700nm) light reflectance of 1.01 is 100%, the relative value of the short wavelength (400nm) light reflectance of 0.98 becomes 97%. That is, in the fourth sample, when the relative value (relative reflectance) of the long-wavelength light reflectance is 100%, the relative value (relative reflectance) of the short-wavelength light reflectance is satisfied to be 95%. above. In addition, the same is true for the 5th to 7th samples, and the 9th and 10th samples.

As shown in the 4th to 7th samples, and the 9th and 10th samples, in the light reflection part 22, when the relative value (relative reflectance) of the long wavelength light reflectance is 100%, The relative value (relative reflectance) of short-wavelength light reflectivity is sufficient to be 95% or more. With this structure, the light reflectance of the light reflecting part 22 can be improved over a wider wavelength range, and the expansion of the light emitting area of the fluorescent part 21 can be suppressed. As a result, the output light incident on the light guide member provided above the phosphor element 1 is increased, and the phosphor element 1 with improved utilization efficiency of the output light is realized.

[Effects, etc.] Invention 1 is a phosphor element 1 including a substrate member 10 and a wavelength conversion member 20; the wavelength conversion member 20 has a fluorescent part 21 and a light reflection part 22 and is provided on the substrate member 10. The fluorescent part 21 has a light incident surface 211 and a light exit surface 212; the light reflection part 22 is provided around the fluorescent part 21 when viewed from the direction of the light exit surface 212. The main component of the fluorescent part 21 is YAG phosphor ceramic containing Ce ³⁺ . The main component of the light reflecting part 22 is light reflective ceramics. The Ce ³⁺ concentration of YAG phosphor ceramics is 0.005% or more and 0.02% or less. The thickness of YAG phosphor ceramic is between 350μm and 820μm.

As shown in FIGS. 9 and 10A , by controlling both the Ce ³⁺ concentration and the thickness of the fluorescent part, in Examples 1 to 4, compared with Review Examples 1 to Review Examples 7, higher light output was achieved. A phosphor element with small angle dependence of chromaticity. The phosphor elements of Examples 1 to 4 described above are equivalent to the phosphor element 1 from the viewpoint of the Ce ³⁺ concentration and thickness of the phosphor part. Therefore, the phosphor element 1 of this embodiment also has the above-mentioned structure, and is an element in which the chromaticity of the output light has small angle dependence.

Furthermore, as shown in FIG. 9 , in Examples 1 to 4, both the chromaticity in the 0° direction and the chromaticity in the 45° direction converged within the above-mentioned chromaticity range (rectangular dotted line). The phosphor elements of the above-mentioned Examples 1 to 4 are elements equivalent to the phosphor element 1. That is, the phosphor element 1 can output light that is converged in the chromaticity range and can be used as an endoscope.

As described above, the phosphor element 1 of this embodiment is an element that outputs output light that converges within a chromaticity range that can be used as an endoscope, and that has a small angular dependence of the chromaticity of the output light. Since the angular dependence of the chromaticity is small, when the fluorescent element 1 is used in an endoscope, the angular dependence of the chromaticity of the light output from the endoscope can be reduced. The phosphor element 1 is used as an endoscope and has higher performance. In addition, as shown in FIG. 10B and Table 5, there are six types of samples (samples equivalent to the phosphor element 1) in which the thickness of the phosphor part 21 (that is, the thickness of the YAG phosphor ceramic) is 350 μm or more and 820 μm or less. The total luminous flux of the output light is above 930lm. Therefore, the phosphor element 1 of this embodiment is an element whose total luminous flux of output light is high enough to be used in an endoscope. To sum up, in this embodiment, the phosphor element 1 with small angular dependence of the chromaticity of the output light and high total luminous flux of the output light is realized; these phosphor elements 1 are used as endoscopes , for components with further higher performance.

Invention 2 is the phosphor element 1 according to Invention 1, wherein the density of the light-reflective ceramic is 95% or less of the theoretical density.

Thereby, as shown in FIG. 11, the light reflectance of the light reflection part 22 (light reflective ceramics) is improved. Therefore, among the output light (white light) emitted from the fluorescent part 21 , the light traveling toward the lateral side is reflected by the light reflecting part 22 , returns to the fluorescent part 21 , and is emitted from the fluorescent part 21 to the outside. Therefore, the output light output from the phosphor element 1 can be increased. Therefore, for example, as shown in FIG. 5 , the total luminous flux of the light guide light based on the output light output from the phosphor element 1 can be further improved.

Invention 3 is the phosphor element 1 according to Invention 1 or 2, wherein in the light-reflective ceramic, when the relative reflectivity of long-wavelength light is 100%, the long-wavelength light is shorter than the short-wavelength light. The relative reflectivity of light is over 95%.

Thereby, as shown in FIGS. 17 and 18 , the light reflectance of the light reflecting portion 22 can be improved over a wider wavelength range, and the expansion of the light-emitting area of the fluorescent portion 21 can be suppressed. As a result, the output light incident on the light guide member provided above the phosphor element 1 is increased, and the phosphor element 1 with improved utilization efficiency of the output light is realized.

Invention 4 is the phosphor element 1 according to any one of Inventions 1 to 3, wherein the density of the YAG phosphor ceramic is 98% or more of the theoretical density.

Thereby, the heat resistance and heat dissipation of the fluorescent part 21 can be improved, and the luminous efficiency of the fluorescent part 21 is less likely to be reduced due to heat. In addition, by using a phosphor ceramic layer as the fluorescent part 21, light loss caused by scattering of fluorescent light can be suppressed, so the conversion efficiency of the fluorescent part 21 can be improved. Therefore, the output light output from the phosphor element 1 can be increased. Therefore, for example, as shown in FIG. 5 , the total luminous flux of the light guide light based on the output light output from the phosphor element 1 can be further improved.

Invention 5 is the phosphor element 1 according to any one of Inventions 1 to 4, wherein the YAG phosphor ceramic has a thickness of 726 μm or more and 820 μm or less.

As shown in FIG. 10C and Table 6, the color temperatures of three types of samples (samples equivalent to the phosphor element 1) in which the thickness of the phosphor part 21 (the thickness of the YAG phosphor ceramic) is 726 μm or more and 820 μm or less are: Above 5050K and below 5810K. Therefore, the color temperature of each output light of the phosphor element 1 of this embodiment (such as these three types of samples) is in a more suitable range, so it is easier to use it in an endoscope.

Invention 6 is the phosphor element 1 according to any one of Inventions 1 to 5, wherein the arithmetic mean roughness Ra of the light incident surface 211 is 20 nm or more and 500 nm or less.

Thereby, as explained in FIG. 10D , the output light of the phosphor element 1 can obtain the same total luminous flux as the output light of the reference sample (1400/8000). In addition, by this, the number of steps and cost for manufacturing the phosphor element 1 of this embodiment can be reduced compared to the sample (1400/8000) in which the Ra of the light incident surface 211 is 11 nm. That is, it is possible to realize a phosphor element 1 that outputs light at a low cost and has a total luminous flux equivalent to that of the reference sample (1400/8000).

Invention 7 is the phosphor element 1 according to any one of Inventions 1 to 6, wherein the main component of the light reflective ceramic is alumina ceramic. The size of the voids in the light reflective ceramic is from 100 nm to 2000 nm.

Thereby, by adjusting the size of the gap, that is, arranging the light scattering portion 23 to be located in this range, the output light (white light) emitted from the fluorescent portion 21 can be reflected by light scattering, so as shown in Figure 11 As shown, the relative value of light reflectivity can be improved.

Invention 8 is a light source module 100 provided with any one of the phosphor elements 1 of Inventions 1 to 7.

As described above, the phosphor element 1 is an element in which the chromaticity of the output light has little dependence on the angle. The light source module 100 including the phosphor element 1 also has a small angle dependence of the chromaticity of the output light. Furthermore, the phosphor element 1 is also an element that outputs output light that is converged in a chromaticity range that can be used as an endoscope, and that has a small angular dependence of the chromaticity of the output light. Therefore, the light source module 100 is also a module that outputs output light that converges in the chromaticity range and can be used as an endoscope, and the chromaticity of the output light has small angle dependence.

(Other embodiments) The phosphor element 1 of the present invention has been described above based on the embodiment. However, the present invention is not limited to the above embodiment. As long as the embodiments do not deviate from the gist of the present invention, various modifications to the embodiments that can be thought of by those skilled in the art and other embodiments constructed by combining the constituent elements of different embodiments are all included in the present invention. range.

For example, in the above-mentioned Embodiments 1 and 2, the substrate member 10 includes the dielectric material multilayer film 12 and the anti-reflection film 13 in addition to the light-transmitting base material 11, but it is not limited to this form. Specifically, the substrate member 10 may not include the dielectric material multilayer film 12 and the anti-reflection film 13 and may be composed of only the light-transmitting base material 11 .

In addition, in the above-described embodiment, the light source module 100 is a transmission-type light-emitting device that transmits the excitation light incident on the phosphor element 1 through the phosphor element 1. However, the light source module 100 is not limited to this form. For example, the light source module 100 may also be a reflective light-emitting device in which the excitation light incident on the phosphor element 1 is not transmitted through the phosphor element 1 but is reflected by the phosphor element 1 . That is, the light source module 100 may be configured so that the light emitted from the light source 2 is reflected by the wavelength conversion member 20 . In this case, the substrate member 10 on which the wavelength conversion member 20 is formed becomes a reflective substrate, and the excitation light is irradiated from above the wavelength conversion member 20 .

In addition, in the above embodiment, the light source module 100 is a fixed light-emitting device that does not move the phosphor element 1, but it is not limited to this form. Specifically, the light source module 100 may be a rotary light-emitting device that rotates the phosphor element 1 . In this case, the phosphor element 1 can be used as a rotating phosphor wheel, for example.

In addition, the substrate member 10 and the wavelength conversion member 20 may also be bonded through a transparent adhesive layer. By bonding the substrate member 10 and the wavelength conversion member 20 via a transparent adhesive layer, and fixing the wavelength conversion member 20 to the substrate member 10, a phosphor element with high physical reliability can be realized.

These phosphor elements will be described below using FIG. 19 .

FIG. 19 is a diagram showing the structure of another example of the phosphor element 3. In FIG. 19 , (a) is a plan view of the phosphor element 3, and (b) is a cross-sectional view of the phosphor element 3 taken along line XIXb-XIXb in (a).

The phosphor element 3 of this other example is different from the phosphor element 1 of the above embodiment in that it is provided with a transparent adhesive layer 30 . That is, the phosphor element 3 includes the substrate member 10 , the wavelength conversion member 20 , and the transparent adhesive layer 30 .

As shown in FIG. 19 , the wavelength conversion component 20 is disposed above the substrate component 10 . Here, the substrate component 10 and the wavelength conversion component 20 are bonded by a transparent adhesive layer 30 . In another example, the light reflection portion 22 of the substrate member 10 and the wavelength conversion member 20 are bonded through the transparent adhesive layer 30; the substrate member 10 and the fluorescent portion 21 of the wavelength conversion member 20 are not bonded through the transparent adhesive layer. 30 and bonding.

A rectangular opening 31 (air layer) is provided in the transparent adhesive layer 30 . Specifically, the transparent adhesive layer 30 has a plan view shape of a rectangular frame with a rectangular opening 31 and a rectangular outer shape. In addition, when viewed from above, the outer shape of the opening 31 is larger than the outer shape of the fluorescent part 21 , and the fluorescent part 21 is included in the opening 31 . In other words, when viewed from above, the fluorescent part 21 and the transparent adhesive layer 30 do not overlap. The fluorescent part 21 is provided above the rectangular opening 31 so that the fluorescent part 21 does not contact the transparent adhesive layer 30 .

The thickness of the transparent adhesive layer 30 is not particularly limited, but is preferably 0.5 μm or more and 50 μm or less. In a preferred embodiment, the thickness of the transparent adhesive layer 30 is between 5 μm and 10 μm.

In this other example, when a light source equivalent to the light source 2 is provided, the light emitted from the light source is incident on the back surface of the substrate member 10 . The light incident on the light source of the substrate member 10 is transmitted through the substrate member 10 and the opening 31 and reaches the fluorescent part 21 of the wavelength conversion member 20 .

At this time, the yellow phosphor (YAG phosphor) of the fluorescent part 21 absorbs part of the blue light from the light source and is excited, and emits yellow light as fluorescence. In the fluorescent part 21, this yellow light is mixed with the blue light of the light source that has not been absorbed by the yellow phosphor to become white light, and this white light is emitted from the fluorescent part 21 as output light. That is, the output light (white light) is taken out from the wavelength converting member 20 .

The refractive index of the fluorescent part 21 and the refractive index of the opening 31 (air layer) located below the fluorescent part 21 have different values. Therefore, the light of the yellow light emitted by the fluorescent part 21 that goes to the light source side is reflected at the interface between the fluorescent part 21 and the opening part 31 due to the difference in refractive index, and goes to the side opposite to the light source side. Therefore, the total luminous flux of the output light taken out from the wavelength converting member 20 can be made higher.

In addition, in the above-mentioned other example, the fluorescent part 21 is not in contact with the transparent adhesive layer 30, but it is not limited to this form. For example, the substrate member 10 and the fluorescent part 21 of the wavelength conversion member 20 may also be bonded through the transparent adhesive layer 30 . In this case, the opening 31 is not provided, and not only the substrate member 10 and the fluorescent part 21 are bonded through the transparent adhesive layer 30 , but the substrate member 10 and the light reflecting part 22 are also bonded through the transparent adhesive layer 30 . bonding. In this case, the heat generated in the fluorescent part 21 due to the irradiation of the excitation light is also dissipated through the transparent adhesive layer 30, so it is unlikely that the luminous efficiency of the fluorescent part 21 is reduced due to heat.

In addition, the Ce ³⁺ concentration of YAG phosphor ceramics can also be within the following range.

The Ce ³⁺ concentration of YAG phosphor ceramic is preferably not less than 0.001% and not more than 0.05%, more preferably not less than 0.002% and not more than 0.04%, further preferably not less than 0.005% and not more than 0.02%. As described above, the lower the concentration, the smaller the angle dependence of the chromaticity of the output light becomes.

In addition, the thickness of the YAG phosphor ceramic is preferably not less than 100 μm and not more than 1500 μm, more preferably not less than 200 μm and not more than 1000 μm, further preferably not less than 350 μm and not more than 820 μm. As described above, when the Ce ³⁺ concentration of the YAG phosphor ceramic is 0.005% or more and 0.02% or less, the angle dependence of the chromaticity of the output light is reduced by making the thickness fall within the above range. In addition, the thickness of the YAG phosphor ceramic may be 350 μm or more and 805 μm or less, it may be 400 μm or more and 805 μm or less, or it may be 659 μm or more and 805 μm or less. As shown in FIG. 9 , by making the thickness fall within the above range, the angular dependence of the chromaticity of the output light becomes smaller.

In addition, the main component of a component means the component that contains the most by weight among the components constituting the component. For example, when the constituent element is the fluorescent part 21, the main component of the fluorescent part 21 refers to the component that contains the most by weight among the components constituting the fluorescent part 21. In the embodiment, it is a YAG fluorescent light containing Ce ³⁺ . Light body ceramics.

Furthermore, more specifically, the main component preferably contains 50% by weight or more of the components constituting the component, more preferably 80% by weight or more, and further preferably 90% by weight or more.

In addition, various changes, substitutions, additions, omissions, etc. can be made to the above-described embodiment within the scope of the invention or its equivalent scope.

1,1x,1a,3: phosphor element 10,10a:Substrate component 100:Light source module 11: Transparent substrate 11a:Side 1 11b: Side 2 12: Dielectric material multilayer film 13: Anti-reflection film 2:Light source 20,20x: Wavelength conversion component 21,21a,25x:fluorescent part 211:Light incident surface 212:Light exit surface 213~216: Side 22:Light reflection part 23:Light scattering part 26x:Binder 3: Phosphor components 30:Transparent adhesive layer 31:Opening part

FIG. 1 is a diagram showing the structure of a phosphor element according to the embodiment. FIG. 2 is a diagram showing the structure of the light source module according to the embodiment. FIG. 3 is a diagram showing the structure of a phosphor element of a comparative example. FIG. 4 is a diagram showing a table of structural elements of the phosphor element of the embodiment and the phosphor element of the comparative example. FIG. 5 is a graph showing the luminescence characteristics of the phosphor element of the embodiment and the phosphor element of the comparative example. FIG. 6 is a cross-sectional view of the phosphor element of Example 1. FIG. 7 is a graph showing the angle dependence of the chromaticity of the output light of the phosphor elements of Review Examples 1 to 3. FIG. FIG. 8 is a graph showing the angle dependence of the chromaticity of the output light of the phosphor elements of Review Examples 4 to 6. FIG. 9 is a graph showing the angle dependence of the chromaticity of the output light of the phosphor elements of Examples 1 to 4 and Review Example 7. Figure 10A is a diagram illustrating the effects of Ce ³⁺ concentration and thickness on excitation light and fluorescence. FIG. 10B is a graph showing the total luminous flux of the output light of nine samples with different thicknesses of the fluorescent parts. FIG. 10C is a graph showing the color temperatures of nine samples with different thicknesses of the fluorescent parts. FIG. 10D is a graph showing the total luminous flux of the output light of a plurality of four types of samples with different surface roughness of the fluorescent part. FIG. 11 is a graph showing relative values of light reflectance of the first to third samples. Fig. 12 is a diagram showing images showing the surface conditions of the first to third samples. FIG. 13 is a diagram showing the luminescence images of three samples with different densities of light reflecting parts. FIG. 14 is a graph showing the area of the fluorescent part, the light-emitting area, and the value of dividing the light-emitting area by the area of the fluorescent part for each of three samples with different densities of light-reflecting parts. FIG. 15 is a diagram showing an example of the light-emitting characteristics of three samples having different densities of light-reflecting parts. FIG. 16 is a diagram showing another example of the light-emitting characteristics of three samples having different densities of light-reflecting parts. FIG. 17 is a graph showing the relative values of light reflectance of the fourth to eighth samples. Fig. 18 is a graph showing the relative values of light reflectance of the ninth to thirteenth samples. FIG. 19 is a diagram showing the structure of another example of a phosphor element.

1:Fluorescent element

10:Substrate components

11: Transparent substrate

11a:Side 1

11b: Side 2

12: Dielectric material multilayer film

13: Anti-reflection film

20:Wavelength conversion component

21: Fluorescence Department

211:Light incident surface

212:Light exit surface

213~216: Side

22:Light reflection part

23:Light scattering part

Claims (8)

A phosphor element includes: a substrate member; and a wavelength conversion member having a fluorescent part and a light reflecting part, which is provided on the substrate member; the fluorescent part has a light incident surface and a light exit surface; from the light exit surface When viewed ⁱⁿ the direction of ; The Ce ³⁺ concentration of the YAG phosphor ceramic is not less than 0.005% and not more than 0.02%; the thickness of the YAG phosphor ceramic is not less than 350 μm and not more than 820 μm. The phosphor component of claim 1, wherein, The density of the light reflective ceramic is less than 95% of the theoretical density. The phosphor component of claim 1, wherein, In this light-reflective ceramic, when the relative reflectance of long-wavelength light is 100%, the relative reflectivity of short-wavelength light having a shorter wavelength than the long wavelength is 95% or more. The phosphor component of claim 1, wherein, The density of the YAG phosphor ceramic is more than 98% of the theoretical density. The phosphor component of claim 1, wherein, The thickness of the YAG phosphor ceramic is 726 μm or more and 820 μm or less. The phosphor component of claim 1, wherein, The arithmetic mean roughness of the light incident surface is 20 nm or more and 500 nm or less. The phosphor component of any one of claims 1 to 6, wherein, The main component of the light reflective ceramic is alumina ceramic; The size of the voids in the light-reflective ceramic is from 100 nm to 2000 nm. A light source module, wherein, Containing the phosphor element according to any one of claims 1 to 7.