JP2006253099A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device with rich color reproducing property with little variation in color tone, and also to provide the light emitting device of high performance and long service life obtaining high light emitting efficiency by preventing deterioration of members comprising the light emitting device. <P>SOLUTION: The light emitting device is constituted of: an excitation light source which radiates excitation light; a light guide which is flexibly extended along a longitudinal direction for guiding the excitation light radiated from the excitation light source; and a wavelength converting member which absorbs and converts the wavelength of the excitation light radiated from the excitation light source through the light guide and releases light with a predetermined wavelength band. The light guide is provided with an end surface with a greater area than a cross sectional area orthogonally crossing in the longitudinal direction on the side on the radiated excitation light and is supported by a light guide tip member and the light guide and at least a part of the light guide tip member are covered by the wavelength converting member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device mainly including an excitation light source, a light guide, a light guide tip member, and a wavelength conversion member.

2. Description of the Related Art Conventionally, there has been a demand for light that can accurately reproduce color information with high luminance in endoscope apparatuses, fiberscopes, and the like.
Therefore, it has been proposed to use a semiconductor light emitting element such as a light emitting diode (LED) or a laser diode (LD) instead of a xenon lamp or the like as these light sources (for example, Patent Documents 1 and 2).
The semiconductor light emitting device is small and has high power efficiency, emits light with a vivid color, and has no fear of a broken ball. In particular, since a laser diode has an emission intensity much higher than that of a light emitting diode, a light source with high illuminance can be realized.
JP 2002-95634 A Special table 2003-515899 gazette

In general, in order to accurately reproduce color information using a semiconductor light emitting element, white light is obtained by combining light of various wavelengths. For example, in order to realize this, a semiconductor device that irradiates light of wavelengths of red, green, and blue is used in combination.
However, since laser diodes have a narrower half-value width than light-emitting diodes, in conventional endoscope devices that use a red, green, and blue laser diode to realize a white light source, the intensity of each laser diode varies, resulting in variations in color tone. Is likely to occur and the color reproducibility is poor. Further, since the conventional endoscope apparatus requires at least three types of laser diodes, the output of each laser diode must be controlled in order to obtain predetermined white light, and the adjustment thereof is difficult. Invite. In addition, since the laser diode has a narrow viewing angle and a very high emission intensity in the front direction as compared with the light emitting diode, there is a problem that even white light has a different color tone due to a slight misalignment of the laser diode.

  Under such circumstances, the present invention provides a light-emitting device that is rich in color reproducibility with little variation in color tone, and that has high performance and can achieve high light-emitting efficiency by preventing deterioration of members constituting the light-emitting device. An object is to provide a light-emitting device having a long lifetime.

The light emitting device of the present invention includes an excitation light source that emits excitation light,
A light guide that extends in a longitudinal direction so as to be bendable and transmits excitation light emitted from the excitation light source;
A light-emitting device comprising a wavelength conversion member that absorbs excitation light emitted from the excitation light source through the light guide, converts the wavelength, and emits light in a predetermined wavelength range;
The light guide has an end face with an area larger than a cross-sectional area perpendicular to the longitudinal direction on the side from which the excitation light is emitted, and is supported by a light guide tip member;
The light guide and at least a part of the light guide tip member are covered with the wavelength conversion member.

In this light emitting device, it is preferable that the light guide tip member has an end surface having an area larger than the cross-sectional area perpendicular to the longitudinal direction on the side from which the excitation light is emitted, and particularly on the side from which the excitation light is emitted. It is preferable to have an end surface having a chamfered edge portion protruding in the longitudinal direction.
In addition, the light guide is preferably configured such that the refractive index of the central portion (core) is higher than the refractive index of the peripheral portion (cladding) in a cross section perpendicular to the longitudinal direction.

Furthermore, it is preferable that unevenness is formed on the side surface of the light guide tip member.
Further, it is preferable that the light guide and / or the light guide tip member has an end surface having irregularities on the side from which the excitation light is emitted.
Further, the excitation light emitted from the excitation light source is preferably laser light.

  According to the light emitting device of the present invention, it is possible to effectively prevent deterioration due to heat generation of the material constituting the wavelength conversion member, and to greatly improve the light output. This is because the light exit side end surface of the light guide has a larger area than the cross-sectional area perpendicular to the longitudinal direction, so that the light density is reduced and the wavelength conversion member is at least part of the light guide tip member. The heat generated in the wavelength conversion member is effectively released to the light guide tip member, and at least a part of the wavelength-converted light is reflected by the end surface of the light guide tip member. It is considered a thing.

  For example, as shown in FIG. 1, the light emitting device 10 of the present invention mainly includes an excitation light source 9, a light guide 20, a light guide tip member 70, and a wavelength conversion member 30.

As shown in FIG. 1, the excitation light source 9 includes a light emitting element 11 and the like, and is configured to guide light emitted from the light emitting element 11 from the emission unit 12 to the light guide 20.
The excitation light source is a light source for emitting excitation light, and may be any light as long as it can excite a fluorescent substance to be described later. As the excitation light source, a device using an energy source such as a semiconductor light emitting element or a lamp, such as an electron beam, plasma, or EL can be used. Among these, it is preferable to use a semiconductor light emitting element. Since the semiconductor light emitting element has high light emission intensity, a small light emitting device with good power efficiency can be obtained. Further, it is possible to obtain a light emitting device that has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Examples of the semiconductor light emitting element include a light emitting diode and a laser diode, and among these, a laser diode is preferable. Thereby, a light emitting device having an extremely high light output can be obtained. For example, it is preferable to emit light having a main emission peak wavelength of about 350 nm to 550 nm. As a result, it is possible to use a fluorescent material with good wavelength conversion efficiency. As a result, it is possible to obtain a light-emitting device with high light output and to obtain light of various colors.
In particular, when a laser diode is used as the excitation light source, the light output is easily improved, but the wavelength conversion member is deteriorated and discolored due to the output improvement. The invention of the present application not only improves the light output, but also can greatly reduce the deterioration of the wavelength conversion member (further, a translucent member, etc.), which will be described in detail later, especially when a laser diode is used as the excitation light source. It is effective.

The light guide light guide 20 guides the light emitted from the excitation light source 9 to the wavelength conversion member 30. The light guide has a desired length, the length can be freely changed, the shape can be freely deformed, in particular, it can be bent or curved at right angles, etc. Since it is configured to be bendable, light can be guided to a desired position. Accordingly, any material and structure may be used as long as it can do this. In particular, it is preferable from the viewpoint of energy efficiency that the light emitted from the excitation light source is led out to the wavelength conversion member without being attenuated.
Since the light guide guides light and is thin enough to bend, the heat generation of the wavelength conversion member disposed at the tip and the concentration of light on the wavelength conversion member are remarkable. Since the wavelength conversion member is deteriorated by heat or light, the wavelength conversion member in such a configuration is very easily deteriorated. The present invention that can effectively reduce the deterioration of the wavelength conversion member is very effective for the light emitting device having such a configuration.

  Examples of the light guide include an extremely thin glass fiber used as a light transmission path when transmitting light, and a combination of a material having a high refractive index and a material having a low refractive index, The thing using a high member can be used. Among them, a double structure having a peripheral portion (clad) surrounding the central portion (core) of a cross section perpendicular to the longitudinal direction of the light guide is preferable, and the refractive index of the core is higher than the refractive index of the cladding. Is more preferable from the viewpoint that the optical signal can be sent without being attenuated. The light guide preferably has a higher core occupancy than a clad occupancy from the viewpoint of reducing the light density at the end face of the light guide. Further, from the viewpoint of preventing return light to the light guide, a smaller cladding diameter is preferable. For example, the core diameter is about 1000 μm or less, the cladding diameter (including the core diameter) is about 1200 μm or less, the core diameter is about 400 μm or less, and the cladding diameter (including the core diameter) is about 450 μm or less. Specific examples include core / clad = 114/125 (μm), 72/80 (μm), and the like. Further, the light guide may have a core or both the clad and the core protruding from the light guide tip member at an end where a wavelength conversion member to be described later is disposed. Thereby, since the light emission area can be increased at the end portion of the light guide, the light density can be further reduced. Even if both the core and the clad are exposed in the longitudinal direction, the light density is reduced because some of the light is emitted from the clad. In order to expose a part of the clad or to expose the core from the clad, for example, it can be formed by a known method such as wet or dry etching or polishing.

The light guide may be either a single fiber or a multi-wire fiber, but is preferably a single fiber. Moreover, either a single mode fiber or a multimode fiber may be used, but a multimode fiber is preferable.
The material of the light guide is not particularly limited, and examples thereof include quartz glass and plastic. Among these, the core material is preferably composed of pure silica (pure quartz). Thereby, transmission loss can be suppressed.

  The light guide has an end face having an area wider than a cross-sectional area perpendicular to the longitudinal direction at one end where the wavelength conversion member is disposed, that is, on the side where the excitation light is emitted. That is, a configuration in which a part or the whole of the light guide end surface has a surface inclined by X ° (0 <X ≦ 90) with respect to the cross section of the light guide (for example, FIGS. 2A to 2G, (i) ), (K) 20), a curved surface (for example, see FIG. 2 (h), (j), (l), (q) 20 etc.), a configuration having a notch in the longitudinal direction (for example, 2 (see FIG. 2 (s)). Specifically, it has 5% or more, 10% or more, 15% or more, 20% or more, 30% or more with respect to the cross section, and has an inclination, a bend, an unevenness, etc. so as to increase the surface area of the end face of one end. It is preferable.

  From the viewpoint of reducing the light density at the end of the light guide, as shown in FIGS. 3A and 3B, the light guide is only at the ends of the light guides 20 and 120 than the center of the cores 20a and 120a. Also, a fiber having a wide core diameter, for example, a TEC fiber (clad 20b diameter is constant) or a tapered fiber (clad 120b diameter is tapered) can be used. Also called index guiding, photonic band gap, hole associated, etc., photonic crystal fiber with one or more air holes in its core or cladding (Osamu Toyama, “Photonics Crystal Fiber” 31st light wave) Sensing Technology Research Group (Proc. Of 31st Meeting on Lightwave Sensing Technology), LST 31-14, pp.89-96, June 6, 2003; Photonic crystal fiber DIAGUIDE ○ RPCF, Mitsubishi Electric Corporation product catalog, No .6-184 (2003.01) etc.) may be used. The end portion of the photonic crystal fiber is covered with a predetermined member in order to prevent moisture and the like from entering the air hole. For this reason, the light transmitted to the light guide is more easily spread and emitted than the core at its end. In any case, since the light density can be reduced at the end of the light guide, the effect of the present invention can be obtained more easily.

  Even in a normal light guide in which the core and / or the clad have a constant diameter, the end portion is covered with a covering member, so that the end portion of the light guide is wider than the core in the same manner as in a photonics crystal fiber. As a result, light is emitted and the light density can be reduced. Here, the film thickness and material of the covering member are not particularly limited as long as they do not hinder the emission of light.

Wavelength Conversion Member The wavelength conversion member in the present invention is preferably composed of at least a fluorescent material, and further includes a holding member for holding it. The wavelength conversion member is disposed so as to cover not only the light guide but also at least a part of the light guide tip member. The wavelength conversion member absorbs part or all of the excitation light emitted from the excitation light source, converts the wavelength, and converts light in a longer wavelength range than the excitation light, for example, red, green, blue, and these It can emit light having an emission spectrum in intermediate colors such as yellow, blue-green, and orange. As a holding member, what can hold | maintain a fluorescent substance, for example, organic members, such as an epoxy resin and a silicone resin, inorganic members, such as glass, etc. are mentioned. Among these, a silicone resin is preferable as a holding member because it is easy to form and has durability against light and heat. The deterioration of the wavelength conversion member may be not only the deterioration of the holding member but also the alteration of the fluorescent material.
The shape of the wavelength conversion member is not particularly limited, and can be various shapes as shown in FIGS. It is preferable to increase the contact area with the wavelength conversion member as much as possible, for example, the wavelength conversion member covers the light guide tip member and the entire end face of the light guide. Thereby, the effect of the present invention can be obtained more easily.

  It is preferable that the wavelength conversion member is made of a material that allows the light finally obtained through the wavelength conversion member to be obtained as white light regardless of the wavelength of the excitation light. In order to obtain good color rendering properties, it is preferable that the average color rendering index (Ra) of the irradiated light is 70 or more, and more preferably 80 or more.

  Here, the color rendering property means the property of the light source that affects the appearance of the color of the object illuminated by a certain light source. Good color rendering property is generally the color of the object illuminated by sunlight. (Refer to Ohm Co., Ltd., “Phosphor Handbook”, p429). Color rendering properties can be improved by using a light emitting element in combination with a fluorescent material layer described later. The average color rendering index (Ra) is obtained based on an average value of color misregistration when eight types of color charts are illuminated by the sample light source and the reference light source, respectively.

  The color tone of the obtained light can be adjusted, for example, by combining light of three primary colors (blue, green, red). Further, it can be adjusted by combining two colors of light such as blue and yellow, blue-green and red, green and red, blue-purple and yellow-green, which are complementary colors. Here, the complementary color means two colors on the opposite sides of the white point in the chromaticity diagram. Note that the light of each color for adjusting the color tone does not necessarily have to be light whose wavelength has been converted by the wavelength conversion member, and excitation light itself obtained from an excitation light source may be used. In the present invention, the relationship between the color of light and the wavelength conforms to JIS Z8110.

  The wavelength conversion member in the present invention may be arbitrarily mixed with a filler. The filler is preferably a material capable of reflecting, scattering and / or diffusing light irradiated from the outside. As a result, excitation light can be uniformly applied to the fluorescent material, color mixing can be performed well, and color unevenness can be reduced. Moreover, since the viscosity can be adjusted by mixing a filler with the wavelength conversion member, the wavelength conversion member can be easily fixed to the light guide.

The wavelength conversion member may be formed of one type of fluorescent material as a single layer, or may be formed of a single layer in which two or more types of fluorescent materials are uniformly mixed. Further, two or more single layers containing one kind of fluorescent substance may be laminated, or for example, two or more single layers in which two or more kinds of fluorescent substances are uniformly mixed may be laminated.
In the case of a light-emitting device using a combination of two or more excitation light sources, the excitation light from each excitation light source is derived by a light guide, and the light emission sides are bundled so that all of them are integrated into a single layer or multiple layers. Alternatively, the wavelength conversion member may be disposed partially and integrally with a single layer or a plurality of layers. Thereby, the process of giving a wavelength conversion member individually can be simplified.

In addition, although the translucent member (wavelength conversion member) which consists of a holding member containing a fluorescent substance etc. was demonstrated here, the translucent member which consists of a holding member etc. which do not contain a fluorescent substance can also be used. Even when a translucent member that does not contain a fluorescent substance is used, basically the same effect as that obtained when the wavelength conversion member described in the effect of the invention is used can be obtained. When a translucent member that does not contain a fluorescent material is used, the light source may be a simple light source, not a light source that excites the fluorescent material, that is, an excitation light source.
Examples of the translucent member that does not include a fluorescent material include only the above-described holding member, and those containing the above-described filler or the like in the holding member. Thereby, the light obtained from the light source can be used without wavelength conversion as it is, and the directivity of the light can be controlled. Moreover, light can be scattered and taken out by containing a filler.

Light Guide Tip Member In the light emitting device of the present invention, the tip of the light guide, that is, the end not connected to the excitation light source is supported by the light guide tip member 70. This improves the light emission efficiency and heat dissipation at the tip of the light guide, and facilitates assembly as a light emitting device. The light guide tip member can be made of any material as long as it has thermal conductivity and reflects at least part of the light after wavelength conversion.
The light guide tip member is preferably a material having high reflectivity, high refractive index, high thermal conductivity or two or more of these properties for excitation light and / or wavelength-converted light. Can be configured. For example, a reflectance of 80% or more for excitation light and / or wavelength-converted light, n: a refractive index of 1.4 or more and / or 0.1 W / m · ° C. for light of about 350 to 500 nm What has the above heat conductivity is preferable. Specific examples include Ag, Al, ZrO ₂ , Al ₂ O ₃ , AlN, borosilicate glass, stainless steel (SUS), carbon, copper, and barium sulfate. In particular, when ZrO ₂ is used, the reflectivity is high, and it is easy to process so that the light guide passes. When stainless steel is used, it is easy to maintain the tensile strength. Therefore, it is preferably formed of ZrO ₂ or stainless steel (for example, SUS303).

  In the light guide tip member, the end surface on the side on which the wavelength conversion member is disposed may be exposed as it is in the cross section of the light guide tip member that intersects perpendicularly to the longitudinal direction (FIGS. 2 (i) to (i)). 70) of p)), and preferably has an inclination, a bend, an unevenness, etc. so as to have an area wider than a cross-sectional area perpendicular to the longitudinal direction. Specifically, a configuration in which a part or all of the end surface of the light guide tip member has a surface inclined by X ° (0 <X ≦ 90) with respect to the cross section (for example, FIGS. 2A to 2G). , (R) to (u) 70) and a curved surface (for example, 70 in FIGS. 2H and 2P). Thereby, the two effects of improving the optical output and reducing the deterioration of the wavelength conversion member can be further improved.

  Furthermore, it is preferable that the light guide tip member has a shape in which a part of the edge is chamfered at one end thereof. That is, it is preferable that a part protruding from the light guide at the edge of the light guide tip member is partially or entirely cut away (for example, refer to 70 in FIGS. 2B and 2E). As a result, the optical output can be further improved and the deterioration of the wavelength conversion member can be further suppressed. The improvement in light output is considered to be because the portion of the edge portion of the light guide tip member that blocks light irradiated from the vicinity of the light guide tip portion can be reduced. It is considered that the deterioration of the wavelength conversion member is suppressed because light is efficiently extracted to the outside by reducing the portion that blocks light, thereby suppressing heat generation.

Moreover, as shown in FIG. 4, it is preferable that the light guide tip member has irregularities (see 80 in FIG. 4) on its side surface. Thereby, the surface area of the light guide tip member is increased, and heat radiation from the light guide or the wavelength conversion member can be increased.
The light guide tip member may support the light guide so that its end surface is flush with one end surface of the light guide (for example, FIGS. 2A to 2H, (q) and (q) t)), the light guide may be supported so as to protrude from the main end face of the tip portion of the light guide tip member (for example, FIG. 2 (k), (l), (n), (o). ) And (r) etc.). In addition, as shown in FIG. 2 (s), the light guide may have a shape in which the peripheral portion (for example, clad) is removed. When a light guide having only the core exposed in the longitudinal direction at the end is used, only the core of the light guide may protrude from the tip of the light guide tip member.

The light guide tip member may be processed such that the end face on which the wavelength conversion member is disposed is preferably mirror-reflected with a mirror, or irregularly reflected by forming predetermined irregularities. Thus, when the excitation light and / or wavelength-converted light once irradiated from the light guide returns to the light guide side by reflection, the excitation light and wavelength are converted by reflecting again by the light guide tip member. The light output can be effectively extracted to the outside, so that the light output is improved. In addition, when unevenness is formed on the end face, the adhesion of the wavelength conversion member to the light guide tip member is improved, the heat dissipation of the wavelength conversion member is increased, and peeling and deterioration of the wavelength conversion member are prevented. can do. In addition, it is preferable that the surface having specular reflection and / or unevenness is formed not only on the light guide tip member but also on the end surface of the light guide.

Lens In the light emitting device of the present invention, for example, as shown in FIG. 1, a lens 13 may be provided between the light emitting element 11 and the emitting portion 12.
The lens may have any shape as long as the light emitted from the light emitting element is collected on the incident portion of the light guide, and a plurality of lenses may be arranged side by side between the light emitting element and the emitting portion. The lens can be formed of inorganic glass, resin, or the like, and among them, inorganic glass is preferable. A lens is provided between the excitation light source and the light guide, and the excitation light emitted from the excitation light source via the lens can be led to the light guide, so that the excitation light emitted from the excitation light source is condensed and efficient. Well can be derived to the light guide.

Embodiment of Light Emitting Device As shown in FIG. 1, the light emitting device of the present invention includes one excitation light source 9, one light guide 20, one light guide tip member 70, and one wavelength conversion member 30. However, at least two of these units may be combined to form a light emitting device. The number of unit combinations can be determined according to color rendering properties and output. In this light emitting device, as described above, the wavelength conversion member of each unit may be integrally formed in a plurality of units.
The brightness of the light emitting device of the present invention is not particularly limited. For example, it is preferable that each unit has a brightness of about 120 lumens / mm ² or more.

Application of Light-Emitting Device The light-emitting device of the present invention can be used for various applications. For example, it may be used as a normal lighting fixture, illumination for mounting on a vehicle (specifically, a light source for a headlight, a tail lamp, etc.) You may utilize for the apparatus for treating while observing. Moreover, you may utilize for the fiberscope for observing a very narrow or dark space, for example, the inside of a nuclear reactor, the closed space of a ruin, etc. Furthermore, it can also be used as a light source in a member that is desired to avoid leakage of electric current, heat generation, etc., such as in the chambers of various vacuum devices. In addition, it can be used as a light-emitting device used in places where a point light source is required or where it is difficult to replace the light source.

  Therefore, this light emitting device uses an imaging member (that is, an electronic component (light receiving element) that converts an optical image into an electrical signal), specifically, a charge-coupled device (CCD), a CMOS image sensor (CMOS), or the like. Used with image sensors, image signal processing devices that convert electrical signals into image signals, indicators that display electrical signals or measured values, displays that output image signals and display images, computers that perform various processes and calculations, etc. can do. In particular, when an imaging element is used as the imaging member, the optical image of the subject can be handled easily.

For example, the light receiving element (for example, a photodiode) may be provided separately from the light emitting device, but is provided in the vicinity of the laser diode in the excitation light source, around the light guide, or in the light guide tip member. Also good. Thereby, the light quantity emitted from the laser diode by the light receiving element is observed, and when the light quantity is less than the constant light quantity, the constant light quantity can be maintained by adjusting the current supplied to the laser diode.
The light emitting device of the present invention has high brightness, little color variation, very good color reproducibility, and very high color rendering, and thus requires clear imaging as in an endoscope device. Excellent effect when used in combination with equipment.

  Furthermore, the light-emitting device of the present invention utilizes visible light obtained by the above-described light-emitting device. For example, a wireless environment can be constructed by adding a communication function to the light-emitting device, and is also used for visible light communication. be able to. Thereby, since a laser diode is used as an excitation light source, a modulation speed of several hundred MHz can be realized.

Hereinafter, specific examples of the light-emitting device of the present invention will be described in detail with reference to the drawings.
Example 1
As shown in FIG. 1, the light emitting device of this embodiment includes an excitation light source 9, a light guide 20, a wavelength conversion member 30, and a light guide tip member 70.
As the excitation light source 9, an LD made of a GaN-based semiconductor having an emission peak wavelength near 405 nm was used as the light emitting element 11. A lens 13 for condensing the excitation light 1 from the LD is disposed on the front surface of the LD.
The light guide 20 has one end connected to the light emitting part 12 of the excitation light source 9 and the other end connected to the output part 21. 1. SI type 114 (μm: core diameter) / 125 (μm: clad diameter) made of quartz is used as the light guide 20, and a direct system made of zirconia (ZrO ₂ ) is used as the light guide tip member 70 that supports the light guide. The thing of 5 mm was used. As shown in FIG. 6B, the end surfaces of the light guide 20 and the light guide tip member 70 of the present embodiment have an inclination angle of 60 ° with respect to the cross section of the surface including the light guide 20. As another surface, the protrusion of the edge portion is eliminated, and the edge portion is processed so as to have an end surface 70a parallel to the cross section.
The end surfaces of the light guide 20 and the light guide tip member 70 were formed by first rough polishing and finally fine polishing with a sheet having a particle size of # 15000.

The wavelength conversion member 30 is molded and attached to the output unit 21 so that the fluorescent material is uniformly dispersed in the resin. That is, the wavelength conversion member 30 is arranged in a single layer structure over the entire end surfaces of both the light guide 20 and the light guide tip member 70.
As the fluorescent material, 0.9 g of Ca ₁₀ (PO ₄ ) _{6 Cl 2} : Eu (CCA) emitting blue light and 0.1 g of Y ₃ Al ₅ O ₁₂ : Ce (YAG) emitting yellow light were used. . These fluorescent materials were kneaded in 1.1 g of silicone resin until uniform, and the wavelength conversion member 30 was produced by potting.

As a comparative example, the light guide and the light guide tip member have one end surface that has a cross section perpendicular to the longitudinal direction of the light guide as shown in FIG. A device was made.
In these light emitting devices, the excitation light source was driven at 70 to 280 mA to evaluate the characteristics.
As a result, as shown in FIG. 7, it was confirmed that in the light emitting device of this example, the maximum value of the luminous flux was improved by about 30% and the light output was improved as compared with the light emitting device of the comparative example.
Note that, according to FIG. 7, in the light emitting device of the comparative example, the luminous flux suddenly decreased when the input current was about 170 mA. The main reason for this is that the wavelength conversion member has deteriorated and discolored. In contrast, in this embodiment, the luminous flux is improved without saturation of the input current up to about 230 mA. From the above results, it can be seen that the wavelength conversion member is more difficult to deteriorate in the light emitting device of this example.

Example 2
The light emitting device of this example was produced in the same manner as in Example 1 except that the light guide and the light guide tip member were polished with a sheet of grain size # 200 to provide a rough surface, that is, unevenness.
When this light-emitting device was evaluated in the same manner as in Example 1, as shown in FIG. 8, the maximum value of the luminous flux was improved by about 50% and the light output was improved as compared with the light-emitting device of the comparative example. confirmed.
By making the interface between the light guide and the light guide tip member and the wavelength conversion member rough, the maximum value of the luminous flux is greatly improved and the deterioration of the wavelength conversion member is reduced. Furthermore, since the output of this example is superior to Example 3 described later, which is similarly rough, the shape of this example shown in FIG. It can be seen that it is preferable to the shape of Example 3 shown in FIG.

Example 3
As shown in FIG. 6A, this light-emitting device has a configuration of the light guide 20, the light guide tip member 70, and the wavelength conversion member 30, and the entire surface is simply 60 ° without removing the protrusions at the edges. An inclined surface was formed. Further, the light guide and the light guide tip member were polished with a sheet having a particle size of # 200 to provide a rough surface, that is, unevenness.
When this light emitting device was evaluated in the same manner as in Example 1, as shown in FIG. 9, the maximum value of the luminous flux was improved by about 30% as compared with the light emitting device of the comparative example, and a high brightness product was obtained. It was confirmed.

  In addition, in Examples 1-3, although the case where the translucent member (wavelength conversion member) which consists of a holding member and a fluorescent substance was provided was demonstrated, each example and except having remove | excluded the fluorescent substance from the wavelength conversion member. A similar light emitting device can also be obtained. That is, it is possible to use a translucent member made of a holding member not containing a fluorescent material, instead of a translucent member made of a holding member containing a fluorescent material. The holding member transmits light from the light source, but in the same way that part of the light absorbed by the fluorescent material is converted into heat without being converted in wavelength, the light from the light source passes through the holding member. It is absorbed without being transmitted and becomes heat. Therefore, even when a translucent member made of a holding member that does not contain a fluorescent substance is used, basically the same effect as that obtained when the wavelength conversion member described in the effect of the invention is used can be obtained. However, in general, more heat is generated from the fluorescent material than heat generated only from the holding member. Therefore, it is more effective when the translucent member has the fluorescent material.

  The light-emitting device of the present invention can be used for lighting fixtures, on-vehicle lighting, displays, indicators, and the like. It can also be used for endoscope devices that image the inside of living bodies, fiberscopes that can illuminate narrow gaps and dark spaces, and various industrial devices that require illumination without current leakage or heat generation. it can.

It is a schematic block diagram for demonstrating the structure of the light-emitting device of this invention. It is a schematic block diagram which shows the light guide and light guide front-end | tip member in the light-emitting device of this invention. It is a schematic block diagram for demonstrating the structure of the light guide edge part in the light-emitting device of this invention. It is a schematic block diagram for demonstrating the structure of the light guide front-end | tip member in the light-emitting device of this invention. It is the schematic for demonstrating arrangement | positioning of the wavelength conversion member in the light-emitting device of this invention. It is a schematic block diagram for demonstrating the structure of the light guide edge part of the light-emitting device in an Example. 6 is a graph showing a relationship between luminous flux and input current of the light emitting device in Example 1. 6 is a graph showing a relationship between luminous flux and input current of a light emitting device in Example 2. 10 is a graph showing a relationship between luminous flux and input current of the light emitting device in Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Excitation light 2 Light 9 Excitation light source 10 Light-emitting device 11 Light-emitting element 12 Injecting part 13 Lens 20, 120 Light guide 20a, 120a Core 20b, 120b Clad 21 Output part 70 Light guide tip member 70a End surface 71 Wavelength conversion light reflection film 72 Excitation Light reflection film 80

Claims (7)

An excitation light source that emits excitation light;
A light guide that extends in a longitudinal direction so as to be bendable and transmits excitation light emitted from the excitation light source;
A light-emitting device comprising a wavelength conversion member that absorbs excitation light emitted from the excitation light source through the light guide, converts the wavelength, and emits light in a predetermined wavelength range;
The light guide has an end face with an area larger than a cross-sectional area perpendicular to the longitudinal direction on the side from which the excitation light is emitted, and is supported by a light guide tip member;
The light-emitting device, wherein the light guide and at least a part of the light guide tip member are covered with the wavelength conversion member.   The light-emitting device according to claim 1, wherein the light guide tip member has an end surface having an area larger than a cross-sectional area perpendicular to the longitudinal direction on the side from which the excitation light is emitted.   The light-emitting device according to claim 2, wherein the light guide distal end member has an end face having a shape in which an edge protruding in the longitudinal direction is chamfered on the side from which the excitation light is emitted.   4. The light guide according to claim 1, wherein a refractive index of a central portion (core) is higher than a refractive index of a peripheral portion (cladding) in a cross section perpendicular to the longitudinal direction. The light emitting device according to one.   The light-emitting device according to claim 1, wherein unevenness is formed on a side surface of the light guide tip member.   The light emitting device according to any one of claims 1 to 5, wherein the light guide and / or the light guide tip member has an uneven end surface on a side from which the excitation light is emitted. The light-emitting device according to claim 1, wherein the excitation light emitted from the excitation light source is laser light.