JP2008293691A - Light emitting device, and optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a light emitting device usable as a point light source, and formed by reducing luminous energy of scattering light without contributing to light emission in an optical fiber including a phosphor; and an optical fiber capable of efficiently converting excitation light to light having a desired wavelength. <P>SOLUTION: The optical fiber included in this light emitting device is configured by forming a light emitting region between a core region and a clad region, and forming a reflecting film outside the clad region. Scattering light in a boundary between the core region and the light emitting region of the optical fiber is reflected by the boundary between the core region and the clad region and the boundary between the clad region and the reflecting film, and emitted to the light emitting region again. Accordingly, the scattering light can be efficiently utilized as excitation light of the phosphor in the light emitting region. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device and an optical fiber, and more particularly to a light emitting device that can be used as a point light source and an optical fiber that can efficiently convert excitation light into light of a desired wavelength.

  An illuminating device using light emission obtained by irradiating a phosphor with excitation light may be replaced with illumination such as a fluorescent lamp, a halogen lamp, or a high intensity discharge (HID) lamp by development of an excellent phosphor or excitation light source. It has been attracting attention.

In addition, a point light source in which such a lighting device is applied and an optical fiber is used to separate a light source portion and a wavelength conversion member containing a phosphor that emits illumination light has been developed (Patent Document 1).
JP 2005-205195 A

  The excitation light applied to the phosphor may be excited on the phosphor or scattered on the phosphor surface. There is also excitation light that leaks from the side surface of the optical fiber without reaching the phosphor. In order to improve the light emission efficiency of the light emitting device, it is desired to reduce the amount of scattered light and excitation light that do not contribute to light emission as much as possible.

  Even when a light-emitting device using an optical fiber is used as a point light source, it is desirable to reduce the amount of scattered light that does not contribute to light emission as much as possible. In the point light source of Patent Document 1, excitation light emitted from an excitation light source is transmitted to a wavelength conversion member including a fluorescent material mixed with a covering member to efficiently convert the wavelength of the excitation light. However, if it is possible to reduce the excitation light that does not contribute to light emission by scattering in the wavelength converting member and not exciting the phosphor, the luminous efficiency can be further increased.

  Accordingly, an object of the present invention is a light-emitting device that can be used as a point light source, and a light-emitting device that reduces the amount of scattered light that does not contribute to light emission in an optical fiber including a phosphor, and excitation light that has a desired wavelength. It is to provide an optical fiber that can be converted efficiently.

  The present invention is a light emitting device including an excitation light source that emits excitation light and an optical fiber. The optical fiber includes a cladding region formed outside a core region, and a reflective film formed outside the cladding region. The present invention relates to a light emitting device in which a light emitting region including a phosphor is formed at least partially in contact with a core region between the core region and the cladding region, and the core region has a higher refractive index than the cladding region.

  In the light emitting device of the present invention, the reflective film preferably contains silver and / or a silver alloy.

  In the light emitting device of the present invention, the material constituting the core region and the cladding region is preferably a resin.

  In the light emitting device of the present invention, the material constituting the core region preferably includes polymethyl methacrylate.

  In the light emitting device of the present invention, it is preferable that the material constituting the cladding region contains a fluorine resin.

  In the light emitting device of the present invention, the light emitting region includes a rare earth activated oxide, a rare earth activated nitride, and semiconductor nanoparticles that emit light having a wavelength of 450 to 700 nm by absorbing excitation light having a wavelength of 380 to 480 nm. It is preferable to include one or more selected phosphors.

  Further, according to the present invention, a cladding region is formed outside the core region, a reflective film is formed outside the cladding region, and the light emitting region containing the phosphor is at least partially in contact with the core region and the cladding region. The phosphor is formed by absorbing the excitation light having a wavelength of 380 to 480 nm to emit light having a wavelength of 450 to 700 nm, and the core region relates to an optical fiber having a refractive index larger than that of the cladding region.

  The present invention was created to solve the above-described problems. Scattered light at the boundary between the core region and the light emitting region of the optical fiber is reflected between the boundary between the core region and the cladding region, and between the cladding region and the reflective film. The light is reflected by the boundary and can be irradiated again to the light emitting region. Then, the scattered light can be efficiently used as excitation light for the phosphor in the light emitting region. Therefore, the light emitting device of the present invention can reduce the amount of scattered light that does not excite the phosphor and does not contribute to light emission, and can efficiently utilize the excitation light from the excitation light source.

  Hereinafter, in the drawings of the present application, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, size, and width in the drawings are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensions.

  In the present invention, the “refractive index” is calculated using, for example, a critical angle method for the core and clad raw material before being processed into a fiber shape, and specifically measured using an Abbe refractometer (manufactured by Atago Co., Ltd.). be able to.

  In addition, the measurement of the emission peak wavelength, emission spectrum, and absorbed excitation light in the phosphor is performed by performing total luminous flux emission spectrum measurement and light absorption spectrum measurement on the phosphor using an integrating sphere. (Reference: Journal of the Illuminating Society of Japan, Vol. 83, No. 2, 1999, p87-93, Measurement of quantum efficiency of NBS standard phosphor, Kazuaki Okubo et al.). For example, a spectrophotometer (manufactured by Horiba, Ltd.) can be used to measure the wavelength of the phosphor light and the wavelength of the excitation light of the light emitting device.

[Light emitting device]
FIG. 1 is a side view schematically showing an embodiment of a light emitting device of the present invention. As shown in FIG. 1, the light emitting device 10 of the present invention includes an optical fiber 1 and an excitation light source 6 that emits excitation light. Excitation light emitted from the excitation light source 6 enters the optical fiber 1 from one end face of the optical fiber 1. Then, the wavelength of the excitation light is converted inside the optical fiber 1 and propagates in the direction opposite to the incident side as indicated by the optical path 8, and from the other end surface of the optical fiber 1 (hereinafter also referred to as a termination). Eject. The inside of the optical fiber 1 contains a phosphor, can convert the wavelength of the excitation light, and can emit light having a wavelength suitable for the application. It is preferable that a lens 7 is provided between the excitation light source 6 and the optical fiber 1, the excitation light is condensed by the lens 7, and the excitation light is efficiently incident on the optical fiber 6 by making the light thin. The light-emitting device 10 of the present invention can be a point light source that emits light having a wavelength suitable for the application by setting the wavelength of light emitted from the excitation light source 6 and appropriately mixing several kinds of the phosphors. Therefore, the light-emitting device 10 can also be a point light source that is close to natural light, for example, by appropriately combining several types of phosphors and mixing the colors of fluorescence emitted by the phosphors. Further, in the light emitting device 10, the excitation light that has entered the optical fiber 1 hardly leaks from the side surfaces other than the end surface of the optical fiber 1, so that the excitation light can be used efficiently.

  The excitation light source 6 of the light emitting device 10 can be a light emitting diode, a semiconductor laser, a tube light source, or the like. However, it is preferable to use a semiconductor laser because it can emit thin light. Examples of the semiconductor laser include those containing a gallium nitride compound semiconductor. Examples of the gallium nitride compound include GaN, AlGaN, InGaN, and InAlGaN. The wavelength of the excitation light emitted from the excitation light source 6 is preferably 380 to 480 nm. When the wavelength is larger than 480 nm, the energy of the excitation light is small, so that the phosphor tends not to be excited. When the wavelength is smaller than 380 nm, the optical fiber 1 is deteriorated and the reliability of the optical fiber 1 is increased. This is because there arises a problem of lowering.

[Configuration of optical fiber]
FIG. 2 is a detailed cross-sectional view of the optical fiber 1 taken along line II-II in FIG. FIG. 3 is a cross-sectional view of the optical fiber 1 taken along line III-III in FIG. The optical fiber 1 in FIG. 2 describes the structure in more detail than the optical fiber 1 in FIG. First, based on FIG. 2, the structure of the preferable optical fiber 1 of this invention is demonstrated. The optical fiber 1 includes a core region 2, a cladding region 4 formed outside the core region 2, and a light emitting region 3 formed in contact with the core region 2 between the core region 2 and the cladding region 4; The reflective film 5 is formed outside the cladding region 4. As shown in FIG. 2, the cross section of the core region 2 is preferably circular. The outer periphery of the cladding region 4 is preferably formed concentrically with the outer periphery of the core region 2. The refractive index of the cladding region 4 is smaller than the refractive index of the core region 2. The reflective film 5 has a higher reflectance than the cladding region 4. The core diameter of the core region 2 is, for example, 1 mm, and the cladding diameter of the cladding region 4 is, for example, 2 mm. The reflective film 5 preferably has a thickness of 1 μm to 0.1 mm, for example. In order to protect the optical fiber 1, a coating such as a resin may be provided outside the reflective film 5.

  Here, the light emitting region 3 refers to a region where the wavelength of the excitation light can be converted and light having a desired wavelength can be emitted, and the light emitting region 3 includes a phosphor. The light emitting region 3 is preferably formed by encapsulating a phosphor in a support made of a highly transparent resin or the like. The amount of the phosphor contained in the support can be set according to the wavelength of the excitation light and the wavelength of the desired light emitted from the optical fiber 1. Further, a phosphor emitting blue light, a phosphor emitting yellow light, a phosphor emitting red light, and the like are appropriately mixed and dispersed in the light emitting region 3 so that, for example, white light is emitted from the end of the optical fiber. It is also possible to emit light.

  In the present invention, the light emitting region 3 is formed at least partially in contact with the core region 2. For example, as shown in FIG. 2, the light emitting region 3 is formed so as to cover the core region 2. The light emitting region 3 may be formed so as to cover the entire core region 2, but is preferably formed so as to partially cover the core region 2 as shown in FIG. 2. Since the excitation light is partially absorbed by the light emitting region 3 while propagating, if the light emitting region 3 is formed so as to cover the entire core region 2, the amount of excitation light gradually decreases in the propagation direction. As a result, the amount of emitted light that inevitably absorbs the amount of excitation light becomes weak. Moreover, even if it has a long distance between excitation light and the light emission area | region 3 of the optical fiber 1, the light quantity absorbed by the light emission area | region 3 can be adjusted by forming so that a part of core region 2 may be covered. This is because a decrease in the intensity of light transmitted by the optical fiber 1 can be minimized. The form and formation site of the light emitting region 3 are determined in view of the relationship between the excitation light and the wavelength of the light emitted from the optical fiber 1 and the light emission amount.

  Next, a cross section viewed from the side of the optical fiber 1 will be described with reference to FIG. As shown in FIG. 3, the light emitting region 3 may be formed so as to be in contact with at least a part of the core region 2 with respect to the longitudinal direction of the core region 2. By appropriately providing a portion where the light emitting region 3 is formed and a portion where the light emitting region 3 is not formed between the core region 2 and the cladding region 4, the light scattering state (light emission intensity) in the propagation direction can be controlled. . Since the amount and direction of excitation light scattering differ depending on the type and size of the phosphor contained in the light emitting region 3, it is necessary to be able to control the light scattering state (light emission intensity) with respect to the propagation direction.

  FIG. 4 is a perspective view of another embodiment of the optical fiber in the present invention. The optical fiber 21 includes a region in which a core-shaped core region 22 is covered with a sheath-shaped light emitting region 23 and a core-shaped core region 22 that is not covered with the light-emitting region 23 with respect to the longitudinal direction. There is a covered area. Moreover, the area | region where the core-shaped core area | region 22 was covered with the sheath-like light emission area | region 23 may differ in a magnitude | size by the location formed as shown in FIG. Thus, the sheath-like light emitting region 23 having a size equal to the equal interval may be formed. Although not shown in FIG. 4, the light emitting region 23 may have a portion in contact with the reflective film 25.

  FIG. 5 is a perspective view of another embodiment of the optical fiber according to the present invention. The core region 32 of the optical fiber 31 is in contact with the elliptical light emitting region 33. At this time, the light emitting regions 33 may be formed at equal intervals in the core region 32 or may be formed at random intervals. Further, the size of the elliptical light emitting region 33 need not be unified. In addition, the light emitting region may be wound around the core region in a spiral shape. In other words, in the optical fiber of the present invention, the formation region of the light emitting region is the desired wavelength of light emitted from the optical fiber, the distance from the excitation light source to the phosphor in the light emitting region inside the optical fiber, the wavelength of light emitted by the optical fiber It is decided according to.

  Although not shown in the above-described figure, a thin layer that does not interfere with light emission from the light emitting region may be sandwiched between the core region and the light emitting region. By sandwiching the thin film, the refractive index can be changed, and the direction of light incident on the light emitting region 23 from the core region 22 can be controlled.

  In the optical fiber of the present invention, both the core region 22 and the cladding region 24 preferably transmit light having a wavelength of 380 to 700 nm, more preferably 400 to 670 nm, in order to transmit excitation light and fluorescence with low loss. . If the wavelength of light transmitted through the optical fiber is less than 380 nm, the light emitted from the terminal has an adverse effect on the human eye, and if the wavelength of light transmitted through the optical fiber exceeds 700 nm, for example, light This is because heat may be held in the fiber, which may deteriorate the properties of the optical fiber and reduce the reliability of the optical fiber.

[Path of light in optical fiber]
FIG. 6 is a cross-sectional view schematically showing the state of light propagation in the optical fiber of the present invention. Hereinafter, the light path in the optical fiber 41 according to the present invention will be described in detail with reference to FIG.

  The excitation light λ1 incident on the core region 42 is the point A at the boundary between the core region 42 and the light emitting region 43 without exciting the light in the light emitting region 43 and the phosphor in the light emitting region 43. Divided into scattered light. Therefore, from the point A, fluorescence λ2 due to light emission from the excited phosphor and scattered light λ3 scattered without exciting the phosphor are emitted. The fluorescence λ <b> 2 proceeds toward the point F at the boundary between the core region 42 and the cladding region 44. If the incident angle to the cladding region 44 at the point F is equal to or greater than the critical angle, the fluorescence λ2 is totally reflected at the point F, and then is appropriately reflected within the optical fiber 41 and emitted from the end of the optical fiber 41. The scattered light λ3 travels toward the point B at the boundary between the core region 42 and the cladding region 44. If the incident angle of the scattered light λ3 to the cladding region 44 is less than the critical angle at the point B, the light λ3 ′ refracted at the point B and traveling straight in the cladding region 44, and the scattered light λ3 reflected at the point B Divided into The light λ3 ′ traveling straight in the cladding region 44 is reflected at a point D at the boundary between the cladding region 44 and the reflective film 45, travels toward the point E at the boundary between the cladding region 44 and the core region 42, and again reaches the core region. Return to 42. Scattered light λ3 reflected at the point B is a point C at the boundary between the core region 42 and the light emitting region 43, and a fluorescent light λ4 emitted from the excited phosphor and a scattered light λ5 scattered without exciting the phosphor. Divided into

  As described above, part of the scattered light λ 3 λ 3 ′ is refracted and travels straight in the cladding region 44 at the point B at the boundary between the core region 42 and the cladding region 44. That is, the light λ 3 ′, which is a part of the scattered light λ 3, does not stay in the core region 42 but leaks to the cladding region 44. According to the present invention, a part of the light λ3 ′ leaking into the cladding region 44 is returned to the core region 42 again, so that the part of the light λ3 ′ is reflected at the point D at the boundary between the cladding region 44 and the reflective film 45. be able to. The light λ <b> 3 ′ reflected at the point D is refracted at the point E at the boundary between the cladding region 44 and the core region 42, returned to the core region 42, and can contribute to excitation of the phosphor in the light emitting region 43. As a result, excitation light can be used efficiently.

  In the optical fiber 41 of the present invention, light is scattered, refracted, reflected and emitted from the excited phosphor as described above. According to the optical fiber 41 of the present invention, it is possible to reduce the loss of light transmitted through the core region 42 and to reduce the amount of light that does not excite the phosphor. Thus, the optical fiber 41 realizes a structure in which incident light is reflected at the boundary between the core region 42 and the cladding region 44 and at the boundary between the cladding region 44 and the reflection film 45.

  Note that the fluorescence emitted from the phosphor excited by the excitation light repeats the same scattering, refraction, and reflection as the excitation light described above, and therefore propagates in the same direction as the propagation direction of the excitation light.

[Material of core region and cladding region]
As described above, the material of the core region and the cladding region constituting the optical fiber is required to have a low transmission loss of 380 to 700 nm over both the excitation light and fluorescence wavelength regions in the present invention. Specifically, a glass material and a resin material that are conventionally used can be appropriately selected and used in accordance with the conditions. However, in the present invention, it is preferable to use the resin material.

  Specifically, as the glass material constituting the optical fiber through which visible light propagates, multicomponent glass such as quartz glass, fluoride, and tellurite is used. However, the glass material generally has a low loss of visible light transmission as compared with the resin material, but has a disadvantage that it is inferior in workability and high in production cost.

  On the other hand, the resin material is rich in workability and has an advantage that the production cost can be reduced when used as a material constituting an optical fiber. Since the light-emitting device of the present invention does not require long-distance transmission, even if the resin material is selected as the material for the core region and the cladding region, the resin material transmits visible light in an optical fiber from the glass material. The high loss is not a problem. In the present invention, the resin material is a concept including a natural resin and a synthetic resin, and the synthetic resin includes a plastic.

  As the material of the core region, it is preferable to use polymethyl methacrylate (hereinafter also referred to as PMMA) among the resin materials. This is because PMMA is excellent in transparency, weather resistance and hardness, is easy to process, easily adjusts the refractive index, and has a lower visible light transmission loss than other plastic materials. . In order to improve the control of refractive index and processability, it may be used by mixing with other plastic materials, such as polycarbonate polymer, fluorine polymer, deuterated polymer, norbornene polymer, polystyrene polymer, Silicone polymers can be used. Note that the refractive index of the core region is preferably set to 1.48 to 1.69, for example.

  It is preferable to use a material having a smaller refractive index than the material of the core region, for example, a fluorine-based resin, as the material of the cladding region. The use of a fluorine-based resin in the cladding region is because the refractive index is lower than that of PMMA and the visible light transmission loss is sufficiently low, and because the plastic material is the same as the core region, there is an advantage that the affinity is high. Specific examples of the fluorine resin include vinylidene fluoride / tetrafluoroethylene copolymer, trifluoroethylene / vinylidene fluoride copolymer, (meth) acrylic acid fluorinated ester polymer, polymethacrylic acid trifluoroester, poly Mention may be made of hexafluoro-2-propyl methacrylate, polypurine purple t-butyl methacrylate, polypurple purple i-propyl methacrylate, and the like. For example, poly-4-methylpentene-1 can be used as the material of the cladding region other than the fluorine-based resin. The refractive index of the cladding region is preferably set to 1.30 to 1.45, for example.

[Material of light emitting area]
The phosphor included in the light emitting region is capable of absorbing fluorescence by emitting excitation light emitted from an excitation light source such as a semiconductor laser element or a light emitting diode.

As described above, the wavelength of the excitation light is preferably longer than 380 nm and more preferably longer than 400 nm in order to suppress visual effects on the human body and deterioration of the plastic fiber. Examples of the phosphor that is efficiently excited at such an excitation light wavelength include (Sr, Ba, Ca) Al ₂ O ₄ : Eu ²⁺ , Y ₃ (Al, Ga) ₅ O ₁₂ : Ce ³⁺ , Y ₂ O _3: rare earth activated oxide phosphor such as Sm ³⁺ and ^{_{CaSiAlN 3: Eu 2+, Ca x}} Si 12- (m + n) Al (m + n) O n n 16-n: Eu 2 ^{_{+, Si 6-z Al z}} O z N 8-z: Eu 2+, M 1-a Ce a Al (Si 6-z Al z) N 10-z O z, (Sr, Ba) Si 2 O 2 It is preferable to use a rare earth activated nitride phosphor such as N ₂ : Eu ²⁺ , Si ₅ AlON ₃ : Eu ²⁺ , LaAl (Si ₅ Al) N ₉ O: Ce 3+. The rare earth activated nitride phosphor of the present invention is a concept that includes one having oxygen O in its crystal structure. Accordingly, a phosphor generally called a rare earth activated oxynitride phosphor is also unified as a rare earth activated nitride phosphor in the present invention. Further, “rare earth activation” indicates that a rare earth element is added as an activator to the base crystal constituting the phosphor.

  Further, as the phosphor of the present invention, a semiconductor nanoparticle phosphor such as InN, InP, ZnTe, CdSe can also be used. In the present invention, the semiconductor nanoparticle phosphor refers to a phosphor having a particle size of nanometer order made of a semiconductor. The rare earth activated oxide phosphor, rare earth activated nitride phosphor, and semiconductor nanoparticle phosphor described above efficiently emit visible light having a wavelength of 450 to 700 nm by absorbing excitation light having a wavelength of 380 to 480 nm. . Moreover, the phosphor contained in the light emitting region may be a single type or a mixture of a plurality of types.

  As for the rare earth activated oxide and the rare earth activated nitride phosphor, those having a particle size of about 0.1 μm to 10 μm are preferably used. When the particle size is larger than this, precipitation tends to occur in the medium, and uniform dispersion of the resin or the like on the support tends to be difficult. On the other hand, if the particle size is smaller than this, surface defects tend to increase and the luminous efficiency tends to decrease.

  About semiconductor nanoparticle fluorescent substance, since a particle size determines light emission wavelength by a quantum size effect, the particle size according to a desired wavelength is suitably selected. For example, in the case of a semiconductor nanoparticle phosphor made of InP, the particle size of the semiconductor nanoparticle phosphor exhibiting blue light with a peak wavelength of 450 nm is 1.8 nm, and the phosphor exhibiting green light with a peak wavelength of 550 nm The particle diameter of the phosphor is 2.4 nm, and the phosphor that exhibits red light having a peak wavelength of 650 nm has a particle diameter of 3 nm.

  The light emitting region is preferably formed by encapsulating a phosphor in a support made of a highly transparent resin or the like. This is because the light emitting region can be easily molded. Specific examples of highly transparent resins include epoxy resins and silicone resins. In addition, the refractive index of the light emitting region 3 is preferably substantially the same as that of the core region 2 so that the excitation light is incident from the core region 2. It is preferable to adjust the filling degree of the phosphor in the light emitting region so that the ratio of the support to the phosphor absorbs most of the excitation light emitted from the excitation light source.

[Material of reflective film]
As a material for the reflective film, a material having high reflectivity such as silver or a silver alloy is suitable. Specific examples of the silver alloy include AgAu, AgPt, AgPd, AgAl, or those obtained by further alloying them. The alloy ratio may be adjusted as appropriate in view of reflectivity and workability during coating.

  In the light emitting device of the present invention, the core region, the cladding region, and the reflective film do not necessarily need to be composed of only a single material.

[Manufacture of light-emitting devices]
The light emitting device of the present invention as shown in FIG. 1 can be manufactured by appropriately combining, for example, the excitation light source 6, the lens 7, and the optical fiber 1.

  The manufacturing method of the optical fiber 1 as shown in FIG. 2 can use a general method of stretching the material of the core region 2, the material of the cladding region 4, and the material of the light emitting region 3 to form a fiber. The reflective film 5 may be formed by stretching the material of the reflective film 5 together with the other materials described above, or may be formed later.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

  Hereinafter, in the examples, an Abbe refractometer (manufactured by Atago Co., Ltd.) was used for measuring the refractive index, and a fluorescence spectrometer (manufactured by Horiba, Ltd.) was used for measuring the excitation light and the wavelength of the phosphor.

<Example 1>
The light emitting device of this example will be described with reference to FIGS.

In this example, a light emitting device 10 as shown in FIG. 1 was manufactured. The light emitting device 10 is configured to collect the excitation light from the excitation light source 6 by the lens 7 and to enter the optical fiber 1. An optical fiber 1 as shown in FIG. 2 has a core region 2 having a refractive index of 1.51 and a cladding region 4 having a refractive index of 1.40, a vinylidene fluoride / tetrafluoroethylene copolymer, and a reflective film 5 having a reflectance. High Ag was used. In addition, a phosphor made of SrAl ₂ O ₄ activated with Eu ²⁺ as a light emission center in the same PMMA as the core region 2 was used as the light emission region 3. The optical fiber 1 was produced by using a general technique for forming a fiber shape by stretching the material of the core region 2, the material of the cladding region 4, the material of the light emitting region 3, and the material of the reflective film 5. The light emitting region 3 was formed so as to contact and cover a part of the core region 2. As the excitation light source 6 of the light emitting device 10, a GaN-based laser that emits light having a wavelength of 405 nm was used.

  In the light emitting device 10 of this embodiment, the excitation light emitted from the excitation light source 6 enters the optical fiber 1, and the incident light is divided into light scattered by the phosphor and fluorescence emitted by the phosphor. Of light can propagate toward the end in the optical fiber 1. From the above, it was possible to obtain the light emitting device 10 as a green point light source with high luminous efficiency.

<Example 2>
A light emitting device according to another embodiment will be described with reference to FIGS. 1 and 2.

In this example, a light emitting device 10 as shown in FIG. 1 was manufactured. The light emitting device 10 is configured to collect the excitation light from the excitation light source 6 by the lens 7 and to enter the optical fiber 1. An optical fiber 1 as shown in FIG. 2 includes a PMMA having a refractive index of 1.51 in the core region 2, a trifluoroethylene / vinylidene fluoride copolymer having a refractive index of 1.39 in the cladding region 4, and a reflectance in the reflecting film 5. A high AgPt alloy was used. Further, a phosphor made of Y ₂ O ₃ activated with Sm ³⁺ as the emission center in the same PMMA as the core region 2 was used as the emission region. The optical fiber 1 was produced by using a general technique for forming a fiber shape by stretching the material of the core region 2, the material of the cladding region 4, the material of the light emitting region 3, and the material of the reflective film 5. The light emitting region 3 was formed so as to contact and cover a part of the core region 2. As the excitation light source 6 of the light emitting device 10, a GaN-based laser that emits light having a wavelength of 405 nm was used.

  In the light emitting device 10 of this embodiment, the excitation light emitted from the excitation light source 6 enters the optical fiber 1, and the incident light is divided into light scattered by the phosphor and fluorescence emitted by the phosphor. Of light can propagate toward the end in the optical fiber 1. From the above, it was possible to obtain the light emitting device 10 as a red point light source with high luminous efficiency.

<Example 3>
In this example, a PMMA / polycarbonate polymer having a refractive index of 1.50 was used for the core region 2 of the optical fiber 1, a perfluorinated polymer having a refractive index of 1.40 was used for the cladding region 4, and an AgPd alloy was used for the reflective film 5. Further, as a light emitting region, a rare earth activated nitride phosphor exhibiting red light made of CaSiAlN ₃ activated with Eu ²⁺ and a rare earth activated phosphor made of Si ₅ AlON ₇ activated with Eu ²⁺ are emitted. A nitride phosphor and a rare earth activated nitride phosphor exhibiting blue light composed of LaAl (Si ₅ Al) N ₉ O activated with Ce ³⁺ were mixed and sealed in the same PMMA as the core region 2 Things were used. Otherwise, the light emitting device 10 of this example was manufactured in the same manner as in Example 1.

  In the light emitting device 10 of this embodiment, the excitation light emitted from the excitation light source 6 enters the optical fiber 1, and the incident light is divided into light scattered by the phosphor and fluorescence emitted by the phosphor. Of light can propagate toward the end in the optical fiber 1. From the above, it was possible to obtain the light emitting device 10 as a white point light source with high luminous efficiency.

<Example 4>
In the present example, the phosphor contained in the light emitting region 3 in Example 3 was activated by using a rare earth activated nitride phosphor composed of CaSiAlN ₃ activated with Eu ²⁺ and exhibiting red light, and activated Eu ²⁺ . and was Si ₅ AlON ₇ 2 rare earth activated nitride phosphor exhibiting green light comprising, as an excitation light source 6, was used an InGaN-based light-emitting diode which emits light having a wavelength of 450nm. The phosphor content of the light emitting region 3 and the area formed in contact with the core region 2 are made smaller than in the case of Example 3, and a part of the excitation light that is blue light propagated from the end of the optical fiber 1 is emitted. I did it. As a result, the light emitted from the red and green phosphors and the excitation light, which is blue light, were mixed to obtain the light emitting device 10 as a white point light source.

  In the present embodiment, the light-emitting diode was used as the excitation light source 6 because it used non-coherent light with high safety in order to use blue excitation light as a component constituting white light. Even when a semiconductor laser is used as the excitation light source 6 in place of the InGaN-based light-emitting diode, the coherency is sufficiently lowered if the semiconductor laser is sufficiently scattered before being emitted from the end of the optical fiber 1, so that it is visually recognized. Can be used as a safe white light component.

<Example 5>
In this example, as the light emitting region of the optical fiber 1, particles exhibiting blue light with a peak wavelength of 450 nm, InP semiconductor nanoparticle phosphors with a particle size of 1.8 nm, and green light with a peak wavelength of 550 nm, A mixture of an InP semiconductor nanoparticle phosphor with a diameter of 2.4 nm and an InP semiconductor nanoparticle phosphor with a particle diameter of 3 nm that exhibits red light having a peak wavelength of 650 nm, and encapsulated in the same PMMA as the core region 2 Was used. Otherwise, the light emitting device 10 of this example was produced in the same manner as in Example 1.

  In the light emitting device 10 of this embodiment, the excitation light emitted from the excitation light source 6 enters the optical fiber 1, and the incident light is divided into light scattered by the phosphor and fluorescence emitted by the phosphor. Of light can propagate toward the end in the optical fiber 1. From the above, it was possible to obtain the light emitting device 10 as a white point light source with high luminous efficiency.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the side view which showed the outline of one Embodiment of the light-emitting device of this invention. It is detailed sectional drawing of the optical fiber 1 along the II-II line | wire of FIG. It is sectional drawing of the optical fiber 1 along the III-III line | wire of FIG. It is a perspective view of another one Embodiment of the optical fiber in this invention. It is a perspective view of another one Embodiment of the optical fiber in this invention. It is sectional drawing which showed typically the mode of the light propagation in the optical fiber of this invention.

Explanation of symbols

  1, 21, 31, 41 Optical fiber, 2, 22, 32, 42 Core region, 3, 23, 33, 43 Light emitting region, 4, 24, 34, 44 Clad region, 5, 25, 35, 45 Reflective film, 6 excitation light source, 7 lens, 8 light path, 10 light emitting device, λ1 excitation light, λ2, λ4 fluorescence, λ3, λ5 scattered light, λ3 ′ light, A, B, C, D, E, F points.

Claims (7)

A light emitting device including an excitation light source that emits excitation light and an optical fiber,
The optical fiber has a cladding region formed outside the core region, a reflective film is formed outside the cladding region,
A light emitting device, wherein a light emitting region including a phosphor is formed at least partially in contact with the core region between the core region and the cladding region, and the core region has a refractive index higher than that of the cladding region.   The light emitting device according to claim 1, wherein the reflective film contains silver and / or a silver alloy.   The light emitting device according to claim 1, wherein a material constituting the core region and the cladding region is a resin material.   The light-emitting device according to claim 3, wherein the material constituting the core region includes polymethyl methacrylate.   The light emitting device according to claim 3, wherein the material constituting the cladding region contains a fluorine-based resin.   The light emitting region includes at least one fluorescence selected from a rare earth activated oxide, a rare earth activated nitride, and semiconductor nanoparticles that emit light having a wavelength of 450 to 700 nm by absorbing the excitation light having a wavelength of 380 to 480 nm. The light emitting device according to claim 1, further comprising a body. A cladding region is formed outside the core region, a reflective film is formed outside the cladding region,
A light emitting region containing a phosphor is formed at least partially in contact between the core region and the cladding region;
The phosphor emits light having a wavelength of 450 to 700 nm by absorbing excitation light having a wavelength of 380 to 480 nm,
An optical fiber, wherein the core region has a refractive index larger than that of the cladding region.

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