JP5302491B2 - LIGHT EMITTING DEVICE AND ENDOSCOPE DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device capable of emitting light of any color with less uneven tone, rich in color reproduction and high color rendition. <P>SOLUTION: The light emitting device comprises a light emitting element 11 to radiate with an excitation light 1, a fluorescent material 31 to absorb the excitation light 1 and convert its wavelength so as to emit an illuminating light 2, and an optical fiber 20 to guide the light radiated from the light emitting element 11 to the fluorescent material 31. The excitation light 1 radiated from the light emitting element 11 is condensed on an output part 21 through a lens 13. The condensed excitation light 1 is projected in the optical fiber 20 and radiated to the fluorescent material 31 coated on the output part 21 provided on a tip of the optical fiber 20 so that the illuminating light 2 from the fluorescent material 31 can be emitted to the outside. <P>COPYRIGHT: (C)2005,JPO&amp;NCIPI

Description

  The present invention relates to a light emitting device having an excitation light source, a wavelength conversion member, and an optical fiber. The present invention also relates to an endoscope apparatus having the light emitting device and an imaging member.

  2. Description of the Related Art Conventionally, endoscope apparatuses for observing the inside of a living body and treating while observing are widely used. An endoscope is composed of an extremely thin optical fiber, but is used as a light source for sending light to the fiber to illuminate the stomach and the like. In order to illuminate thin fibers efficiently, high brightness is required. In addition, color information is important for diagnosing an affected area while visually observing an illuminated image. For this reason, a light source close to natural light is required. Furthermore, in order to reduce the waiting time of the patient after turning on the light source, a light source that can be turned on and stabilized instantaneously is required. For this reason, conventionally, a xenon lamp or a metal halide lamp is used as a light source.

  However, xenon lamps and metal halide lamps cannot realize vivid colors, and have problems that it takes time for the emission color to stabilize, and that it cannot be turned on again instantaneously. For this reason, a lamp using a light emitting element is used as an alternative to a xenon lamp or a metal halide lamp.

  A light-emitting device using a light-emitting element emits light with a small color, high power efficiency, and vivid colors. In addition, since the light-emitting element is a semiconductor element, there is no fear of a broken ball. Further, it has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting. Because of such excellent characteristics, light-emitting devices using semiconductor light-emitting elements such as light-emitting diode elements (LEDs) and laser diode elements (LDs) are used as various light sources. Since the endoscope apparatus is used for medical purposes, the lighting apparatus is required to have extremely high reliability and reliable lighting performance. Also, the lamp is not allowed to go out during the operation.

For example, in the conventional endoscope apparatus 100 shown in FIG. 12, the white light source 111 in the illumination unit 110 includes a red semiconductor laser 111a, a green semiconductor laser 111b, and a blue semiconductor laser 111c, and each semiconductor laser has a plurality of interferences. The multi-longitudinal mode light having a spectral distribution of the wavelength λ is emitted, and the GaN-based semiconductor laser 114 also emits multi-longitudinal mode excitation light with less interference (see, for example, Patent Document 1). ). This endoscope apparatus realizes white light by using light mixture of the three primary colors of light of the red semiconductor laser 111a, the green semiconductor laser 111b, and the blue semiconductor laser 111c. Since a semiconductor laser has an emission intensity much higher than that of a light emitting diode, an endoscope apparatus with high illuminance is realized.
JP 2002-95634 A

  However, since the semiconductor laser has a narrower half-value width than the light emitting diode, in the conventional endoscope apparatus that realizes the white light source 111 using the red semiconductor laser 111a, the green semiconductor laser 111b, and the blue semiconductor laser 111c, Different intensities tend to cause color variation, resulting in poor color reproducibility. In addition, since the conventional endoscope apparatus requires at least three types of semiconductor lasers, the output of each semiconductor laser must be controlled to obtain predetermined white light, and the adjustment thereof is difficult. Invite. In addition, since the semiconductor laser has a narrow viewing angle and a very high emission intensity in the front direction compared to a light emitting diode, there is a problem that even white light has a different color tone due to a slight misalignment of the semiconductor laser. Furthermore, there is a demand for an endoscopic device with high color rendering properties, but there is a problem that conventional endoscope devices cannot achieve high color rendering properties.

  In view of the above, an object of the present invention is to provide a light-emitting device with little color variation and high color reproducibility, to provide a light-emitting device that emits any color, and to provide a light-emitting device with high color rendering properties. And

In order to solve the above-mentioned problems, the present inventors have intensively studied and as a result, the present invention has been completed.
A first light-emitting device according to the present invention includes:
An excitation light source that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
The excitation light source is provided at one end, the wavelength converting member is provided at the other end, and the refractive index of the central portion (core) of the cross section is made higher than that of the peripheral portion (cladding). possess an optical fiber to derive the conversion member,
The wavelength converting member includes a fluorescent material and a filler, and a difference in center particle diameter between the fluorescent material and the filler is less than 20% .
The second light emitting device according to the present invention is:
An excitation light source that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
Possess an optical fiber to derive the center portion of the cross section of the illumination light emitted refractive index from higher than to the wavelength conversion member periphery (cladding) of the (core) to the outside,
The wavelength converting member includes a fluorescent material and a filler, and a difference in center particle diameter between the fluorescent material and the filler is less than 20%.

The third light emitting device according to the present invention is:
An excitation light source that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
The excitation light source is provided at one end, the wavelength converting member is provided at the other end, and the refractive index of the central portion (core) of the cross section is made higher than that of the peripheral portion (cladding). An optical fiber led to the conversion member,
The wavelength conversion member includes a fluorescent material and a filler, and a circularity difference between the fluorescent material and the filler is less than 20%.
A fourth light emitting device according to the present invention includes:
An excitation light source that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
An optical fiber for leading the illumination light emitted from the wavelength conversion member to the outside by making the refractive index of the central part (core) of the cross section higher than that of the peripheral part (cladding),
The wavelength conversion member includes a fluorescent material and a filler, and a circularity difference between the fluorescent material and the filler is less than 20%.

The wavelength conversion member may include a fluorescent material.
The wavelength conversion member preferably contains at least a part of a nitride fluorescent material.
The wavelength conversion member preferably contains at least a part of a rare earth aluminate fluorescent material.
The wavelength conversion member preferably contains at least a part of a fluorescent material having good temperature characteristics.
Furthermore, it is preferable that the fluorescent material contains at least a part of lutetium aluminum garnet.
The wavelength conversion member may be mixed with the covering member.

The excitation light source is preferably a light emitting element.
The excitation light emitted from the excitation light source is preferably laser light.
The excitation light source preferably has an emission peak wavelength from 350 nm to 500 nm.

The light emitting device may guide the excitation light emitted from the excitation light source to the optical fiber via a lens provided between the excitation light source and the optical fiber.
The light emitting device may have a blocking member that blocks 90% or more of light from the excitation light source.
The light emitting device preferably has an average color rendering index (Ra) of 80 or more.
The present invention relates to an endoscope apparatus including the light-emitting device and an imaging member that irradiates a subject with light emitted from the light-emitting device and captures a normal image using light reflected from the subject.
The imaging member is preferably an imaging element.

Since the present invention is configured as described above, the following effects can be obtained.
A first light emitting device according to the present invention includes an excitation light source that emits excitation light, a wavelength conversion member that absorbs excitation light emitted from the excitation light source, converts the wavelength, and emits illumination light in a predetermined wavelength range. The excitation light source is provided at one end, the wavelength conversion member is provided at the other end, and the refractive index of the central part (core) of the cross section is made higher than that of the peripheral part (cladding), and the excitation light emitted from the excitation light source is Since the optical fiber led out to the wavelength conversion member is provided and the wavelength conversion member is provided at the other end, the excitation light emitted from the excitation light source 10 is irradiated to the wavelength conversion member and diffused. Since heat generated from the excitation light source is not transferred to the wavelength conversion member by separating the excitation light source and the wavelength conversion member, deterioration of the wavelength conversion member due to heat can be suppressed. Further, since substantially all of the excitation light emitted from the excitation light source is transmitted to the wavelength conversion member mixed in the covering member, only the wavelength conversion member mixed in the covering member is emitted from the light emitting device. Therefore, the wavelength of the excitation light can be efficiently converted. In addition, it is possible to provide a light emitting device having a wider directivity angle than a light emitting device that does not include a wavelength conversion member. Furthermore, since a predetermined emission color can be realized with at least one excitation light source, a light-emitting device with little color variation and high color reproducibility can be provided. Moreover, the position away from the excitation light source can be irradiated through the optical fiber. Furthermore, since the excitation light source and the wavelength conversion member are connected via an optical fiber and the heat generated from the excitation light source is not transferred to the wavelength conversion member by separating the excitation light source and the wavelength conversion member, the wavelength conversion member Deterioration due to heat can be suppressed.

  A second light emitting device according to the present invention includes an excitation light source that emits excitation light, a wavelength conversion member that absorbs excitation light emitted from the excitation light source, converts the wavelength, and emits illumination light in a predetermined wavelength range. And an optical fiber for leading the illumination light emitted from the wavelength conversion member to the outside by setting the refractive index of the central portion (core) of the cross section to be higher than that of the peripheral portion (cladding), and at least one excitation Since a predetermined color tone can be realized with a light source, a light-emitting device with little color variation and high color reproducibility can be provided. Moreover, the position away from the excitation light source can be irradiated through the optical fiber. Furthermore, it can also be used in places where the tip of the optical fiber is dirty. In addition, since the wavelength conversion member can be disposed on the excitation light source side, the wavelength conversion member can be easily replaced. In addition, productivity can be improved by providing the wavelength conversion member at various positions.

  The optical fiber can be transmitted to the outside while maintaining a predetermined output state without attenuating the output of the excitation light emitted from the excitation light source or the illumination light emitted from the wavelength conversion member. Further, since no electricity flows through the optical fiber, problems such as electric leakage do not occur. Furthermore, since the excitation light source and the wavelength conversion member can be separated from each other by a certain distance, heat generated by the excitation light source is not transferred to the wavelength conversion member, and deterioration of the wavelength conversion member due to heat can be prevented.

By using a fluorescent material as the wavelength conversion member, it is possible to provide a light emitting device with high light emission luminance and color rendering properties.
By containing at least a part of the nitride fluorescent material as the wavelength conversion member, the nitride fluorescent material is excited by light on the short wavelength side from ultraviolet to visible light, and emits light on the long wavelength side of visible light. Therefore, the color rendering property can be improved.
By containing at least a part of the rare earth aluminate fluorescent material as the wavelength conversion member, the rare earth aluminate fluorescent material has high heat resistance, so that stable illumination light can be emitted. Further, since the rare earth aluminate fluorescent material has high wavelength conversion efficiency, light can be extracted efficiently.

  In particular, when the wavelength conversion member contains at least a part of a fluorescent substance having good temperature characteristics, typically lutetium aluminum garnet (LAG), the wavelength conversion member, Deterioration of the light emitting device itself can be effectively prevented. In addition, the present inventors surprisingly, in the present application, when using a fluorescent material having a good temperature characteristic, any excitation light source, for example, a light source with a very high light output such as a laser beam. It has been found for the first time that degradation of light flux due to an increase in light output can be effectively prevented even in the case of using. That is, the light flux with respect to the light output can be increased substantially linearly. As a result, it is possible to obtain a light emitting device with extremely high output and high brightness and high reliability and long life.

The wavelength converting member can be easily fixed to the optical fiber by mixing with the covering member. In addition, since the wavelength conversion member can be arranged uniformly, a light emitting device with less color unevenness can be provided.
Since the excitation light source is a light emitting element, it is possible to provide a light emitting device that is small and has high power efficiency. In addition, it is possible to provide a light-emitting device that has excellent initial driving characteristics and is strong against vibration and repeated on / off lighting.

Since the excitation light emitted from the excitation light source is a laser beam, a light emitting device having an extremely high light emission output can be provided.
Since the excitation light source has an emission peak wavelength from 350 nm to 500 nm, an excitation light source in the short wavelength region of ultraviolet light or visible light and a wavelength conversion member that is wavelength-converted by excitation light from the excitation light source are combined. A light emitting device with high light output can be provided. In addition, light-emitting devices with various colors can be provided.

  The light-emitting device condenses the excitation light emitted from the excitation light source efficiently by extracting the excitation light emitted from the excitation light source to the optical fiber via a lens provided between the excitation light source and the optical fiber. Can be derived to an optical fiber.

The light-emitting device can take out only a predetermined wavelength by having a blocking member that blocks 90% or more of light from the excitation light source. In particular, irradiation with ultraviolet rays can be suppressed by providing a blocking member such as an ultraviolet absorber.
When the average color rendering index (Ra) is 80 or more, the light emitting device can provide a light emitting device with high color rendering properties.

The endoscope apparatus according to the present invention includes the light-emitting device and an imaging member that irradiates a subject with light emitted from the light-emitting device and captures a normal image using light reflected from the subject. It is possible to provide an endoscope apparatus with little variation and high color reproducibility. In addition, since a light emitting device with high color rendering properties is used, clear imaging can be performed.
Since the imaging member is an imaging element, it is possible to easily handle an optical image of a subject.

  Hereinafter, a light-emitting device, an endoscope device, and a manufacturing method thereof according to the present invention will be described using embodiments and examples. However, the present invention is not limited to this embodiment and example.

<First Embodiment>
<Light emitting device>
The light emitting device according to the first embodiment will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a light emitting device according to the present invention.
The light emitting device according to the first embodiment absorbs the excitation light 1 emitted from the excitation light source 10 and the excitation light 1 emitted from the excitation light source 10, converts the wavelength of the illumination light 2 in a predetermined wavelength range. The wavelength conversion member 30 to be emitted, the excitation light source 10 at one end, the wavelength conversion member 30 at the other end, the refractive index of the central portion (core) of the cross section is made higher than the peripheral portion (cladding), and the excitation light source 10 And an optical fiber 20 that guides the emitted excitation light 1 to the wavelength conversion member 30.

  The excitation light source 10 includes a light emitting element 11 and guides light emitted from the light emitting element 11 from the emitting unit 12 to the optical fiber 20. In order to efficiently guide the light emitted from the light emitting element 11 to the emitting unit 12, a lens 13 is provided between the light emitting element 11 and the emitting unit 12.

  One end of the optical fiber 20 is connected to the emitting unit 12, and the other end includes an output unit 21 that guides light to the outside. The output unit 21 has a wavelength conversion member 30. A fluorescent material 31 is used as the wavelength conversion member 30. The wavelength conversion member 30 absorbs the excitation light 1 emitted from the excitation light source 10, converts the wavelength, and emits illumination light 2 in a predetermined wavelength range, and is disposed in the output unit 21.

  When using a light emitting element 11 having an emission peak wavelength near 400 nm in a short wavelength region of visible light, and a fluorescent material 31 in which a fluorescent material 31 that emits blue light and a fluorescent material 31 that emits yellow light are used. White light emitted from the substance 31 is mainly the illumination light 2. Since light near 400 nm is difficult to visually recognize, blue light, yellow light, and white light that are easy to visually recognize become the illumination light 2.

  When the light emitting element 11 having an emission peak wavelength near 460 nm in the short wavelength region of visible light, the fluorescent substance 31 that emits yellow light, and the fluorescent substance 31 that emits red light, excitation light emitted from the light emitting element 11 is used. 1 and light emitted from the fluorescent material 31 are led to the outside as illumination light 2. This illumination light 2 becomes reddish white light.

  In the case of using the light emitting element 11 having an emission peak wavelength near 365 nm in the ultraviolet region and the fluorescent material 31 in which the fluorescent material 31 emitting blue light and the fluorescent material 31 emitting yellow light are used, emission from the fluorescent material 31 The emitted light becomes the illumination light 2. Since the ultraviolet rays cannot be seen by human eyes, only the light emitted from the fluorescent material 31 whose wavelength is converted to visible light becomes the illumination light 2. Therefore, the white light emitted from the fluorescent material 31 becomes the illumination light 2.

  However, various combinations of the fluorescent materials 31 are conceivable. When obtaining a wide range of colors using the three primary colors of light (blue, green, and red), blue and yellow, blue-green and red, and green and red are complementary colors. In some cases, various colors are obtained using two colors such as blue-purple and yellow-green. One of these colors may be replaced with light emitted from the light emitting element 11. Here, complementary color means that light in a white region is obtained when light having one emission peak wavelength and light having the other emission peak wavelength are mixed. Here, JIS Z8110 is taken into consideration for the relationship between the color name and the wavelength range.

  Color rendering is a property of a light source that affects how an object color illuminated by a light source looks. The color temperature is a psychophysical expression of the color of the light source itself, and is expressed by the absolute temperature (K) of a perfect radiator having a chromaticity equal to the chromaticity of a certain light source. In general, it is represented by how much the object color seen under a certain light source is different from the object color seen under the reference light having the same color temperature. The average color rendering index (Ra) is obtained on the basis of an average value of color misregistration when eight kinds of color charts are illuminated by the sample light source and the reference light source, respectively. The special color rendering index is obtained on the basis of individual color shifts of seven types of color charts other than the above eight types of color charts, and is not an average of the seven types. Of these, R9 is red.

Next, the operation of the light emitting device will be described.
Excitation light 1 emitted from the light emitting element 11 provided in the excitation light source 10 passes through the lens 13 and is guided to the emission unit 12. The lens 13 focuses the excitation light 1 emitted from the light emitting element 11 on the emission unit 12. The excitation light 1 emitted from the emission unit 12 is guided to the optical fiber 20. The excitation light 1 is led to the output unit 21 which is the other end while repeating total reflection in the optical fiber 20. The excitation light 1 that has been led out to the fluorescent material 31 that is the wavelength conversion member 30 provided in the output unit 21 is irradiated. At least a part of the excitation light 1 is absorbed by the fluorescent material 31 and converted in wavelength to emit light in a predetermined wavelength region. This light becomes illumination light 2 and is led out. Alternatively, the illumination light 2 in which the light emitted from the fluorescent material 31 and the excitation light 1 are mixed is led out.

  Thereby, white light can be obtained with at least one light emitting element 11. In addition, since white light can be obtained with only one light emitting element 11, a light emitting device with little color variation and high color reproducibility can be provided. Further, since the light emitting element 11 and the fluorescent material 31 are used, it is possible to provide a light emitting device that easily mixes colors and has high color rendering properties. In addition, a light-emitting device with high emission intensity can be provided. Since the fluorescent material 31 is not applied to the light emitting element 11, the fluorescent material 31 does not deteriorate due to heat generated by driving the light emitting element 11.

<Excitation light source>
The excitation light source 10 only needs to be able to emit light that excites the fluorescent material 31, and a semiconductor light emitting element, lamp, electron beam, plasma, EL, or the like can be used as an energy source. Although not particularly limited, it is preferable to use the light-emitting element 11 because of its small size and high emission intensity. As the light emitting element 11, a light emitting diode element (LED), a laser diode element (LD), or the like can be used.

(Light emitting element A)
The light emitting element 11 is preferably a semiconductor light emitting element having a light emitting layer capable of emitting a light emission wavelength capable of efficiently exciting the fluorescent material 31. Examples of the material of such a semiconductor light emitting device include various semiconductors such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements may contain Si, Zn, or the like as an impurity element to serve as a light emission center. In particular, a nitride semiconductor (for example, a nitride semiconductor containing Al or Ga, a nitride containing In or Ga, or the like) as a material of a light emitting layer capable of efficiently emitting a short wavelength of visible light from the ultraviolet region that can excite the phosphor 31 efficiently. As the physical semiconductor, In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, and X + Y ≦ 1) are more preferable.

  As a semiconductor structure, a homostructure having a MIS junction, a PIN junction, a pn junction, or the like, a heterostructure, or a double hetero configuration is preferably exemplified. Various emission wavelengths can be selected depending on the semiconductor layer material and the mixed crystal ratio. Further, the output can be further improved by adopting a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film that produces a quantum effect.

  When a nitride semiconductor is used for the light emitting element 11, a material such as sapphire, spinel, SiC, Si, ZnO, GaAs, GaN or the like is suitably used for the semiconductor substrate. In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate by HVPE method, MOCVD method or the like. A buffer layer made of GaN, AlN, GaAIN or the like is grown at a low temperature on the sapphire substrate to form a non-single crystal, and a nitride semiconductor having a pn junction is formed thereon.

As an example of the light-emitting element 11 that can efficiently emit light in an ultraviolet region having a pn junction using a nitride semiconductor, SiO ₂ is formed on the buffer layer in a stripe shape substantially perpendicular to the orientation flat surface of the sapphire substrate. GaN is grown on the stripes using EHV (Epitaxial Lateral Over Grows GaN) using the HVPE method. Subsequently, a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum nitride / gallium, a well layer of indium nitride / aluminum / gallium, and aluminum nitride / gallium are formed by MOCVD. An active layer having a multiple quantum well structure in which a plurality of barrier layers are stacked, a second cladding layer formed of p-type aluminum nitride / gallium, and a second contact layer formed of p-type gallium nitride are sequentially stacked. Examples include a double hetero configuration. The active layer may be formed into a ridge stripe shape and sandwiched between guide layers, and a resonator end face may be provided to provide a semiconductor laser device usable in the present invention.

  Nitride semiconductors exhibit n-type conductivity without being doped with impurities. When forming a desired n-type nitride semiconductor, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, etc. as an n-type dopant. On the other hand, when forming a p-type nitride semiconductor, it is preferable to dope p-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba. Since nitride semiconductors are not easily converted to p-type by simply doping with a p-type dopant, it is preferable to reduce resistance by heating in a furnace or plasma irradiation after introducing the p-type dopant. When a sapphire substrate is not used, the contact layer is exposed by etching from the p-type side to the surface of the first contact layer. A light emitting element made of a nitride semiconductor can be formed by cutting the semiconductor wafer into chips after forming electrodes on each contact layer.

  When fixing the fluorescent substance 31 to the output part, it is preferable to form it using resin. In this case, the emission peak wavelength of the light emitting element 11 can be 350 nm or more and 500 nm or less in consideration of the emission wavelength from the fluorescent material 31 and the deterioration of the translucent resin.

Here, in the light-emitting element 11, the sheet resistance of the n-type contact layer formed at an impurity concentration of 10 ¹⁷ to 10 ²⁰ / cm ³ and the sheet resistance of the translucent p-electrode have a relationship of Rp ≧ Rn. It is preferable to be adjusted to. The n-type contact layer is preferably formed to a film thickness of, for example, 3 to 10 μm, more preferably 4 to 6 μm, and the sheet resistance is estimated to be 10 to 15Ω / □, so that Rp at this time is the sheet resistance value. It is good to form in a thin film so that it may have the above sheet resistance values. The translucent p-electrode may be formed of a thin film having a thickness of 150 μm or less.

  Further, when the translucent p-electrode is formed of a multilayer film or alloy composed of one kind selected from the group of gold and platinum group elements and at least one other element, it is contained. When the sheet resistance of the translucent p-electrode is adjusted by the content of the gold or platinum group element, stability and reproducibility are improved. Since gold or a metal element has a high absorption coefficient in the wavelength region of the semiconductor light emitting device used in the present invention, the smaller the amount of gold or platinum group element contained in the translucent p-electrode, the better the transparency. In the conventional semiconductor light emitting device, the relationship of sheet resistance is Rp ≦ Rn. However, in the present invention, Rp ≧ Rn, and therefore the translucent p-electrode is formed in a thin film as compared with the conventional one. However, thinning can be easily performed by reducing the content of gold or platinum group elements.

  As described above, in the light emitting element 11, it is preferable that the sheet resistance RnΩ / □ of the n-type contact layer and the sheet resistance RpΩ / □ of the translucent p electrode satisfy the relationship of Rp ≧ Rn. It is difficult to measure Rn after forming as the light emitting element 11 and it is practically impossible to know the relationship between Rp and Rn. However, from the state of the light intensity distribution at the time of light emission, what kind of Rp and Rn You can know if they are in a relationship.

  When the translucent p-electrode and the n-type contact layer have a relationship of Rp ≧ Rn, providing a p-side pedestal electrode in contact with the translucent p-electrode and having an extended conductive portion further improves external quantum efficiency. Can be achieved. There is no limitation on the shape and direction of the extended conductive portion, and when the extended conductive portion is on the satellite, it is preferable because the area for blocking light is reduced, but a mesh shape may be used. Further, the shape may be a curved shape, a lattice shape, a branch shape, or a hook shape in addition to the straight shape. At this time, since the light shielding effect increases in proportion to the total area of the p-side pedestal electrode, it is preferable to design the line width and length of the extended conductive portion so that the light shielding effect does not exceed the light emission enhancing effect.

(Light emitting element B)
As the light-emitting element 11, a light-emitting element that emits blue light different from the above-described ultraviolet light-emitting element can be used. The light emitting element 11 that emits blue light is preferably a group III nitride compound light emitting element. The light emitting element 11 includes, for example, an n-type GaN layer in which Si is undoped, an n-type contact layer made of n-type GaN doped with Si, an undoped GaN layer, and a multiple quantum well structure on a sapphire substrate 1 via a GaN buffer layer. Luminescent layer (GaN barrier layer / InGaN well layer quantum well structure), Mg-doped p-type GaN p-type GaN cladding layer, Mg-doped p-type GaN p-type contact layer Are sequentially stacked, and electrodes are formed as follows. However, a light emitting element different from this configuration can also be used.

The p ohmic electrode is formed on almost the entire surface of the p-type contact layer, and the p pad electrode is formed on a part of the p ohmic electrode.
The n-electrode is formed in the exposed portion by removing the undoped GaN layer from the p-type contact layer by etching to expose a part of the n-type contact layer.
In the present embodiment, a light emitting layer having a multiple quantum well structure is used. However, the present invention is not limited to this, and for example, a single quantum well structure using InGaN may be used. GaN doped with Zn may be used.

  The light emitting layer of the light emitting element 11 can change the main light emission peak wavelength in the range of 420 nm to 490 nm by changing the In content. The emission peak wavelength is not limited to the above range, and those having an emission peak wavelength in the range of 350 to 550 nm can be used.

(Light emitting element C)
Emitting element 11, a nitride semiconductor, for example, GaN, AlN or InN, or a gallium nitride-based compound is these mixed crystal semiconductor _{(In x Al y Ga 1-} xy N, 0 ≦ x, 0 ≦ y, x + y ≦ 1 ). Moreover, you may use what substituted a part of this gallium nitride type compound semiconductor by B and P. Such a light emitting element can be formed as a laser diode element, for example.

In a nitride semiconductor laser, an active layer made of In _x Ga _1-x N (0 ≦ x <1) is formed on an GaN substrate by an n-type Al _y Ga _1-y N (0 ≦ y <1) layer (each layer). Each of which has a different y value) and a p-type Al _z Ga _1-z N (0 ≦ z <1) layer (the z value is different for each layer), forming a so-called double heterostructure. Has been.

The active layer is an In _x1 Al _y1 Ga _1-x1-y1 N well layer (0 ≦ x ₁ ≦ 1, 0 ≦ y ₁ ≦ 1, 0 ≦ x ₁ + y ₁ ≦ 1) and In _x2 Al _y2 Ga _{1-x2 -y2} N barrier layer (0 ≦ x ₂ ≦ 1, 0 ≦ y ₁ ≦ 1, 0 ≦ x ₁ + y ₁ ≦ 1, x ₁ > x ₂ ) is an appropriate number of times in the order of barrier layer-well layer-barrier layer In this case, both ends of the active layer are barrier layers. The well layer is formed undoped. On the other hand, except for the final barrier layer adjacent to the p-type electron confinement layer, all the barrier layers are doped with n-type impurities such as Si and Sn, and the final barrier layer is grown undoped. In the final barrier layer, p-type impurities such as Mg are diffused from the adjacent p-type nitride semiconductor layer.

  Since the barrier layer except the final barrier layer is doped with n-type impurities, the initial electron concentration in the active layer is increased, the efficiency of electron injection into the well layer is increased, and the laser emission efficiency is improved. On the other hand, since the final barrier layer is closest to the p-type layer, it does not contribute to electron injection into the well layer. Therefore, the hole injection efficiency into the well layer can be increased by not doping the final barrier layer with the n-type impurity, but rather by substantially doping the p-type impurity by diffusion from the p-type layer. In addition, by not doping the final barrier layer with n-type impurities, it is possible to prevent different types of impurities from being mixed in the barrier layer and lowering the carrier mobility.

The details of the structure of the nitride semiconductor laser will be described below. As the substrate, GaN is preferably used, but a heterogeneous substrate different from the nitride semiconductor may be used. Examples of the heterogeneous substrate include, for example, sapphire, spinel (including an insulating substrate such as MgA1 ₂ O ₄ , SiC (including 6H, 4H, and 3C) having any one of the C-plane, R-plane, and A-plane. It has been conventionally known that a nitride semiconductor such as ZnS, ZnO, GaAs, Si, and an oxide substrate lattice-matched with a nitride semiconductor can be grown, and a substrate material different from the nitride semiconductor can be used. Preferred examples of the heterogeneous substrate include sapphire and spinel, and the heterogeneous substrate may be off-angled, and if an off-angle substrate is used in this case, the underlying layer made of gallium nitride has good crystallinity. Furthermore, in the case of using a heterogeneous substrate, after growing a nitride semiconductor serving as a base layer before forming the element structure on the heterogeneous substrate, the heterogeneous substrate is used. Is removed by a method such as polishing, may form a device structure as a single substrate of nitride semiconductor, also after device structure formation, a heterogeneous substrate or a method of removing.

  In the case of using a heterogeneous substrate, if the element structure is formed via a base layer made of a buffer layer (low temperature growth layer) and a nitride semiconductor (preferably GaN), the growth of the nitride semiconductor becomes good. In addition, as a base layer (growth substrate) provided on a heterogeneous substrate, a growth substrate with good crystallinity can be obtained by using a nitride semiconductor grown by ELOG. As a specific example of the ELOG growth layer, a nitride semiconductor layer is grown on a heterogeneous substrate, a mask region formed by providing a protective film on which the nitride semiconductor growth is difficult, and a nitride semiconductor are formed. A non-mask region to be grown is provided in a stripe shape, and a nitride semiconductor is grown from the non-mask region, so that the growth in the lateral direction is achieved in addition to the growth in the film thickness direction. There is also a layer formed by growing a nitride semiconductor. In another form, the nitride semiconductor layer grown on the different kind of substrate may be provided with an opening, and the film may be formed by lateral growth from the side of the opening.

  An n-type contact layer, a crack prevention layer, an n-type cladding layer, and an n-type light guide layer, which are n-type nitride semiconductor layers, are formed on the substrate via a buffer layer. Other layers other than the n-type cladding layer may be omitted depending on the element. The n-type nitride semiconductor layer needs to have a wider band gap than that of the active layer at least in a portion in contact with the active layer, and therefore, preferably has a composition containing Al. Each layer may be grown while doping with n-type impurities to be n-type, or may be grown undoped to be n-type.

An active layer is formed on the n-type nitride semiconductor layer. As described above, the active layer is an In _x1 Al _y1 Ga _1-x1-y1 N well layer (0 ≦ x ₁ ≦ 1, 0 ≦ y ₁ ≦ 1, 0 ≦ x ₁ + y ₁ ≦ 1) and In _x2 Al _y2 Ga _1-x2-y2 N barrier layers (0 ≦ x ₂ ≦ 1, 0 ≦ y ₁ ≦ 1, 0 ≦ x ₁ + y ₁ ≦ 1, x ₁ > x ₂ ) were alternately and repeatedly stacked an appropriate number of times. It has an MQW structure, and both ends of the active layer are barrier layers. The well layer is undoped, and all the barrier layers except the final barrier layer are doped with n-type impurities such as Si and Sn, preferably at a concentration of 1 × 10 ¹⁷ to 1 × 10 ¹⁹ cm ^−3. Is formed.

The final barrier layer is formed undoped, and contains p-type impurities such as Mg by 1 × 10 ¹⁶ to 1 × 10 ¹⁹ cm ⁻³ by diffusion from the p-type electron confinement layer to be grown next. When the final barrier layer is grown, it may be grown while doping a p-type impurity such as Mg at a concentration of 1 × 10 ¹⁹ cm ⁻³ or less. The final barrier layer is formed thicker than the other barrier layers in order to suppress the influence of decomposition by gas etching when the p-type electron confinement layer is grown next. The suitable thickness of the final barrier layer varies depending on the growth conditions of the p-type electron confinement layer. For example, the thickness is preferably 1.1 to 10 times, more preferably 1.1 to 5 times that of the other barrier layers. To grow. Thus, the final barrier layer serves as a protective film that prevents the decomposition of the active layer containing In.

  On the final barrier layer, as a p-type nitride semiconductor layer, a p-type electron confinement layer, a p-type light guide layer, a p-type cladding layer, and a p-type contact layer are formed. Other layers other than the p-type cladding layer may be omitted depending on the element. The p-type nitride semiconductor layer needs to have a wider band gap than that of the active layer at least in a portion in contact with the active layer, and therefore, it is preferably a composition containing Al. Each layer may be grown while doping with p-type impurities to be p-type, or p-type impurities may be diffused from other adjacent layers to be p-type.

The p-type electron confinement layer is made of a p-type nitride semiconductor having an Al mixed crystal ratio higher than that of the p-type cladding layer, and preferably has a composition of Al _x Ga _1-x N (0.1 <x <0.5). Have Further, a p-type impurity such as Mg is doped at a high concentration, preferably 5 × 10 ¹⁷ to 1 × 10 ¹⁹ cm ⁻³ . Thereby, the p-type electron confinement layer can effectively confine electrons in the active layer, and lowers the threshold of the laser. Further, the p-type electron confinement layer may be grown as a thin film of about 30 to 200 mm, and if it is a thin film, it can be grown at a lower temperature than the p-type light guide layer and the p-type optical cladding layer. Therefore, by forming the p-type electron confinement layer, decomposition of the active layer containing In can be suppressed as compared with the case where the p-type light guide layer or the like is formed directly on the active layer.

The p-type electron confinement layer plays a role of supplying p-type impurities to the final barrier layer grown by undoping by diffusion, and both cooperate to protect the active layer from decomposition and to the active layer. It plays a role in increasing the hole injection efficiency. That is, an undoped In _x2 Ga _1-x2 N layer (0 ≦ x ₂ <1) is formed thicker than the other barrier layers as the final layer of the MQW active layer, and a p-type impurity such as Mg is formed thereon at a high concentration. By growing a thin film made of doped p-type Al _x Ga _1-x N (0.1 <x <0.5) at a low temperature, the active layer containing In is protected from decomposition, and the p-type Al _x A p-type impurity such as Mg diffuses from the Ga _1-x N layer to the undoped In _x2 Ga _1-x2 N layer, so that the efficiency of hole injection into the active layer can be improved.

Among the p-type nitride semiconductor layers, a ridge stripe is formed up to the middle of the p-type light guide layer, and further, a protective film, a p-type electrode, an n-type electrode, a p-pad electrode, and an n-pad electrode are formed. It is configured.
The laser light preferably has an emission peak wavelength from 350 nm to 500 nm. By using the laser beam in this range, it is possible to use the fluorescent material 31 with good wavelength conversion efficiency. Moreover, deterioration of the resin mixed with the fluorescent material 31 can be suppressed by making the range.

<Wavelength conversion member>
The wavelength conversion member 30 is not particularly limited as long as it absorbs the excitation light emitted from the excitation light source 10, converts the wavelength, and emits illumination light in a predetermined wavelength range. it can. The emission spectrum of the excitation light source 10 and the emission spectrum of the wavelength conversion member 30 are different. In order to use the light emitted from the excitation light source 10 as excitation light, the wavelength conversion member 30 has an emission peak wavelength on the longer wavelength side than the emission peak wavelength of the excitation light source 10. In particular, even when a laser diode element is used as the light-emitting element 11, the illumination light has a broad emission spectrum with a wide half-value width, and thus is easily visible.

(Fluorescent substance)
The fluorescent material 31 is not particularly limited as long as it is excited by an excitation light source.
(i) a lanthanoid series such as Eu, an alkaline earth metal halogen apatite mainly activated by a transition metal series element such as Mn,
(ii) alkaline earth metal halogen borate,
(iii) alkaline earth metal aluminate,
(iv) oxynitrides or nitrides mainly activated with rare earth elements,
(v) alkaline earth silicate, alkaline earth silicon nitride,
(vi) sulfides,
(vii) alkaline earth thiogallate,
(viii) germanate,
(ix) rare earth aluminates mainly activated with lanthanoid elements such as Ce,
(x) rare earth silicates,
(xi) Various fluorescent materials such as organic and organic complexes mainly activated with a lanthanoid element such as Eu. These can be used alone or in combination of two or more.

(i) As an alkaline earth metal halogen apatite fluorescent material mainly activated by a lanthanoid-based element such as Eu or a transition metal-based element such as Mn,
M ₅ (PO ₄ ) ₃ X: R
(M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is at least one selected from F, Cl, Br, I. R is Eu and / or Mn.)
Etc.
For example, calcium chlorapatite (CCA), barium chlorapatite (BCA), etc. are exemplified, and specifically, Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, (Ba, Ca) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu and the like.

(ii) Alkaline earth metal halogen borate fluorescent substance
M ₂ B ₅ O ₉ X: R
(M is at least one selected from Sr, Ca, Ba, Mg, Zn. X is at least one selected from F, Cl, Br, I. R is Eu and / or Mn.)
Etc.
For example, calcium chlorborate (CCB) is exemplified, and specific examples include Ca ₂ B ₅ O ₉ Cl: Eu.
(iii) Alkaline earth metal aluminate fluorescent materials include europium activated strontium aluminate (SAE), barium magnesium aluminate (BAM), or SrAl ₂ O ₄ : R, Sr ₄ Al ₁₄ O ₂₅ : R, CaAl ₂ O ₄ : R, BaMg ₂ Al ₁₆ O ₂₇ : R, BaMgAl ₁₀ O ₁₇ : R (R is Eu and / or Mn) and the like.

(iv) The oxynitride phosphor mainly activated by rare earth elements includes at least one Group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, C, And at least one Group IV element selected from the group consisting of Si, Ge, Sn, Ti, Zr, and Hf. The combination of these elements is not particularly limited, for example, the following composition,
L _{X MY} O _Z N _{((2/3) X + (4/3) Y- (2/3) Z)} : R or
L _{X MY} Q _T O _Z N _{((2/3) X + (4/3) Y + T- (2/3) Z)} : R
(L is at least one group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Zn. M consists of C, Si, Ge, Sn, Ti, Zr, and Hf. At least one Group IV element selected from the group, Q is at least one Group III element selected from the group consisting of B, Al, Ga, and In, and R is Y, La, Ce , Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Lu, Yb, and Tm. At least one rare earth element selected from the group consisting of 0.5 <X <1.5, 1 .5 <Y <2.5, 0 <T <0.5, 1.5 <Z <2.5.)
Are preferred. In the formula, when X, Y, and Z are in the above-described ranges, high luminance is exhibited, and in particular, the oxynitride phosphors represented by X = 1, Y = 2, and Z = 2 exhibit higher luminance. Therefore, it is more preferable. However, it is not limited to the said range, Arbitrary things can be used.
Specifically, an oxynitride phosphor having alpha sialon as a base material, an oxynitride phosphor having beta sialon as a base material, Eu activated calcium aluminum silicon nitride represented by a composition formula of CaAlSiN ₃ : Eu, and the like Can be mentioned.

  The nitride phosphor is activated by at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Lu, Yb, and Tm. The The fluorescent material is selected from the group consisting of at least one group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn and C, Si, Ge, Sn, Ti, Zr, Hf. Nitride phosphor containing at least one kind of group IV element and N, wherein B is contained in the range of 1 to 10000 ppm. Alternatively, oxygen may be included in the composition of the nitride fluorescent material.

Among them, Eu activated calcium silicon nitride (CESN), Eu activated strontium silicon nitride (SESN), Eu activated calcium strontium silicon nitride (SCESN), especially activated by Eu, and Ca and / or Sr, Si and N is preferably a nitride fluorescent material containing N in a range of 1 to 10,000 ppm.
A part of Eu is substituted with at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Lu, Yb, and Tm. Also good. A part of Ca and / or Sr may be substituted with at least one Group II element selected from the group consisting of Be, Mg, Ba, and Zn. A part of Si may be substituted with at least one Group IV element selected from the group consisting of C, Ge, Sn, Ti, Zr, and Hf.

In particular,
L _{X MY} N _{((2/3) X + (4/3) Y)} : R or
L _{X MY} O _Z N _{((2/3) X + (4/3) Y- (2/3) Z)} : R
(L is at least one group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, and Zn. M consists of C, Si, Ge, Sn, Ti, Zr, and Hf. At least one Group IV element selected from the group, wherein R is a group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Lu, Yb, and Tm. (At least one rare earth element selected from the group consisting of X, Y, and Z is 0.5 ≦ X ≦ 3, 1.5 ≦ Y ≦ 8, and 0 <Z ≦ 3.)
A nitride fluorescent material represented by the formula (1), wherein B is contained in the range of 1 to 10000 ppm is preferable.

(v) As alkaline earth silicate and alkaline earth silicon nitride, M ₂ Si ₅ N ₈ : Eu, MSi ₇ N ₁₀ : Eu, M _1.8 Si ₅ O _0.2 N ₈ : Eu, M _0.9 Si ₇ O _0.1 N ₁₀ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, and Zn).

(vi) As sulfides, alkaline earth sulfides such as CaS: Eu, SrS: Eu, La ₂ O ₂ S: Eu, Y ₂ O ₂ S: Eu, Gd ₂ O ₂ S: Eu, ZnS : Eu, ZnS: Mn, ZnCdS: Cu, ZnCdS: Ag, Al, ZnCdS: Cu, Al, etc.
(vii) Examples of the alkaline earth thiogallate include MGa ₂ S ₄ : Eu (M is at least one selected from Sr, Ca, Ba, Mg and Zn).
(viii) Examples of the germanate include 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn, Zn ₂ GeO ₄ : Mn, and the like.

(ix) Rare earth aluminates mainly activated with lanthanoid elements such as Ce include yttrium aluminum garnet (YAG), lutetium aluminum garnet (LAG), specifically, Y ₃ Al ₅ O ₁₂ : Ce, _{(Y 0.8 Gd 0.2) 3 Al} 5 O 12: Ce, Y 3 (Al 0.8 Ga 0.2) 5 O 12: Ce, (Y, Gd) 3 (Al, Ga) 5 O 12: Ce, Y 3 (Al, Sc) ₅ O ₁₂ : Ce, Lu ₃ Al ₅ O ₁₂ : Ce, Tb ₃ Al ₅ O ₁₂ : Ce, Gd ₃ (Al, Ga) ₅ O ₁₂ : Ce, and the like. Among these, from the viewpoint of obtaining light with higher luminance, LAG having good temperature characteristics is preferable. In addition, since these rare earth aluminates can change a temperature characteristic with the quantity of an activation element, from a viewpoint of obtaining high brightness | luminance, for example, 0.006-3 mol ratio, Preferably 0.01-3 mol It is preferable to use an activation element with a ratio, more preferably about 0.03 to 2 molar ratio.
Examples of (x) rare earth silicates include Y ₂ SiO ₅ : Ce, Y ₂ SiO ₅ : Tb.
(xi) Organic and organic complexes mainly activated with a lanthanoid element such as Eu are not particularly limited, and any known one may be used.
As the above-mentioned fluorescent material, at least one selected from Tb, Cu, Ag, Au, Cr, Nd, Dy, Co, Ni, Ti and the like may be used instead of or in addition to Eu. Good.

Among them, (ix) rare earth aluminate phosphors mainly activated with lanthanoid elements such as Ce, particularly Y ₃ Al ₅ O ₁₂ : Ce, (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, etc. YAG-based fluorescent materials represented by the composition formula (including those in which Y is partially or fully substituted with Lu, and those in which Ce is partially or completely substituted with Tb) and (iv) mainly activated with rare earth elements oxynitride or nitride fluorescent material, in particular, the general formula _{L X M Y N ((2/3} ) X + (4/3) Y): R or _{L X M Y O Z N (} (2/3) X + _{(4/3) Y- (2/3) Z)} : R (L is at least one Group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn. M is , C, Si, Ge, Sn, Ti, Zr, Hf, at least one group IV element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, E and at least one rare earth element selected from the group consisting of r, Lu, Yb, and Tm, where X, Y, and Z are 0.5 ≦ X ≦ 3, 1.5 ≦ Y ≦ 8, and 0 <Z ≦ 3. It is preferable to use a mixture of Thereby, a light emitting device with high color rendering properties can be obtained.

  Also, (i) a combination of at least one of CCA, (ii) CCB and (iii) BAM and (ix) YAG, (iii) a combination of SAE and (i) CCA: Mn, (iii) SAE and ( The combination of iv) CESN, (ix) LAG and (iv) CESN, and (ix) LAG and (iv) SCESN are preferred.

Furthermore, from another point of view, it is preferable that the fluorescent material contains at least a part having good temperature characteristics. Here, "the one having good temperature characteristics" means that the luminance does not decrease remarkably even when the temperature of the wavelength conversion member is increased by laser light irradiation, compared to the luminance of the wavelength conversion member at room temperature. To do. Specifically, the wavelength conversion member has a luminance maintenance rate at 250 ° C. of 50% or more, preferably 55% or more, 60% or more, 65% or more, or 70% or more with respect to the luminance maintenance rate at room temperature. Things. The wavelength conversion member has a luminance maintenance factor at 300 ° C. of 30% or more, preferably 35% or more, 40% or more, 45% or more, or 50% or more of the luminance maintenance factor at room temperature. It is done. More preferably, the luminance maintenance factor at 250 ° C. is 50% or more, preferably 55% or more, 60% or more, 65% or more, or 70% or more, and the luminance maintenance factor at 300 ° C. Examples include those of 30% or more, preferably 35% or more, 40% or more, 45% or more, or 50% or more with respect to room temperature. Typical examples of such a fluorescent substance include LAG, BAM, YAG, CCA, SCA, SCESN, SESN, CESN, and CaAlSiN ₃ : Eu. Of these, LAG, BAM, CaAlSiN ₃ : Eu and the like are preferable. Thereby, higher luminance can be realized.
A fluorescent substance other than the above-described fluorescent substance, which has the same performance and effect, can also be used.

  These fluorescent materials 31 can use fluorescent materials having emission spectra in yellow, red, green, and blue by the excitation light of the light-emitting element 11, and in addition to these intermediate colors such as yellow, blue-green, and orange A fluorescent material having an emission spectrum can also be used. By using a combination of two or more fluorescent materials 31, light emitting devices having various emission colors can be manufactured.

For example, CaSi ₂ O ₂ N ₂ : Eu, which emits light from green to yellow, or SrSi ₂ O ₂ N ₂ : Eu, and (Sr, Ca) ₅ (PO ₄ ) ₃ Cl: Eu, which emits blue light, emits red light. By using the fluorescent material 31 composed of (Ca, Sr) ₂ Si ₅ N ₈ : Eu, a light emitting device that emits white light with good color rendering can be provided. This uses the three primary colors of red, blue, and green, so that desired white light can be realized only by changing the blending ratio of the fluorescent material 31.

  The particle size of the fluorescent material 31 is preferably in the range of 1 μm to 20 μm, more preferably 2 μm to 8 μm. Particularly, 5 μm to 8 μm is preferable. The fluorescent material 31 having a particle size smaller than 2 μm tends to form an aggregate. On the other hand, the fluorescent material 31 having a particle size range of 5 μm to 8 μm has a high light absorption rate and conversion efficiency. As described above, the mass productivity of the light-emitting device is improved by including a fluorescent substance having a large particle diameter and having optically excellent characteristics.

Here, the particle size refers to the average particle size obtained by the air permeation method. Specifically, in an environment with an air temperature of 25 ° C. and a humidity of 70%, a sample of 1 cm ³ is weighed and packed in a special tubular container, and then a constant pressure of dry air is flowed to read the specific surface area from the differential pressure. It is a value converted into an average particle diameter.

(Coating member)
The wavelength conversion member can be formed by previously mixing the above-described fluorescent material with a predetermined covering member. The covering member is preferably an inorganic substance, but an organic substance can also be used. For example, as the covering member, an inorganic glass, yttria sol, alumina sol, silica sol, or the like can be used in addition to a resin such as a silicone resin, an epoxy resin, a modified silicone resin, and a modified epoxy resin. Those excellent in heat resistance, light resistance, weather resistance, translucency and the like are preferable. In the wavelength conversion member, the amount of the fluorescent material can be adjusted by the amount of the covering member.

<Optical fiber>
The optical fiber 20 only needs to have a function of deriving the light emitted from the excitation light source 10 to the wavelength conversion member 30. In particular, it is preferable from the viewpoint of energy efficiency that the light emitted from the excitation light source 10 is led out to the wavelength conversion member 30 without being attenuated. For example, a combination of a material having a high refractive index and a material having a low refractive index, or a material using a member having a high reflectance can be used. Specifically, the optical fiber 20 can be used.

The optical fiber 20 is an extremely thin glass fiber used as a light transmission path when transmitting light. By using quartz glass or plastic as a material, and making the refractive index of the central part (core) of the cross section higher than that of the peripheral part (cladding), the optical signal can be sent without being attenuated.
Since the optical fiber 20 is movable, the illumination light 2 can be irradiated to a desired position. Moreover, the optical fiber 20 can also be bent into a curve. The optical fiber 20 can be a single fiber. The core diameter of the single fiber is preferably 400 μm or less.

<Lens>
The lens 13 can also be provided between the light emitting element 11 and the emitting portion 12. Not only one lens 13 but also a plurality of lenses can be used. A shape in which light emitted from the light emitting element 11 is transmitted through the lens 13 and condensed on the emission unit 12 is used. The lens 13 is preferably inorganic glass, but resin or the like can also be used.

<Filler>
A filler may be mixed with the fluorescent material 31 in the resin. As specific fillers, barium titanate, titanium oxide, aluminum oxide, silicon oxide and the like are preferable. As a result, color unevenness can be reduced. The filler also includes a diffusing agent.

  Here, the particle size of the filler is not particularly limited. The filler having a center particle size of 1 μm or more and less than 5 μm can diffuse irregularly the light from the fluorescent material 31 and suppress uneven color that tends to occur by using the fluorescent material 31 having a large particle size. The filler having a center particle size of 1 nm or more and less than 1 μm has a low interference effect on the light wavelength from the light emitting element 11, but can increase the resin viscosity without reducing the luminous intensity. Thereby, it becomes possible to disperse | distribute the fluorescent substance 31 in resin substantially uniformly, and to maintain the state. Thereby, even when a fluorescent substance having a large particle size, which is relatively difficult to handle, is used, it can be mass-produced with a high yield. When a filler having a center particle size of 5 μm or more and 100 μm or less is contained in the resin, the chromaticity variation of the light emitting element 11 is improved by the light scattering action, and the thermal shock resistance of the resin can be enhanced.

  The filler preferably has a particle size and / or shape similar to that of the fluorescent material 31. Here, the similar particle diameter means a case where the difference between the respective center particle diameters of each particle is less than 20%, and the similar shape means a circularity (circularity) indicating an approximate degree of each particle diameter with a perfect circle. This is the case where the difference in the value of degree = peripheral length of perfect circle equal to projected area of particle / perimeter length of projected particle) is less than 20% By using such a filler, the fluorescent material 31 and the filler interact with each other, and the fluorescent material 31 can be favorably dispersed in the resin, and color unevenness is suppressed.

<Blocking member>
As the blocking member, a member that blocks 90% or more of light from the excitation light source can be used. For example, when the light emitting element 11 that emits ultraviolet rays harmful to the human body is used, an ultraviolet absorber can be used as a blocking member in order to block the ultraviolet rays. A predetermined filter may be provided in the output unit 21 to block a predetermined wavelength.

<Endoscope device>
FIG. 2 is a schematic configuration diagram showing an endoscope apparatus according to the present invention.
An endoscope apparatus having the light emitting device according to the first embodiment and an imaging member that irradiates a subject with light emitted from the light emitting device and captures a normal image by light reflected from the subject is described. To do.
The endoscope apparatus according to the present invention is used when observing the inside of a living body, which is the subject 50, or performing treatment while observing.
The endoscope apparatus includes a light emitting device and an imaging member 40, and the imaging member 40 includes an image signal processing unit 41, an imaging element 42, and a cable 43.

  The excitation light 1 emitted from the light emitting element 11 is sent to the output unit 21 including the fluorescent material 31 through the optical fiber 20. The transmitted excitation light 1 is wavelength-converted by the fluorescent material 31 and the illumination light 2 is emitted to the outside. This illumination light 2 is applied to the affected area of the patient, which is the subject 50. A part of the light irradiated to the subject 50 is absorbed and a part is reflected. The reflected light 3 that is reflected is imaged by the image sensor 42. The image signal processing unit 41 includes a television monitor, transmits an image signal captured by the image sensor 42 to the image signal processing unit 41, processes the image signal by the image signal processing unit 41, and displays an image of the subject 50 on the television monitor. Project.

  A camera head including an image sensor 42 that images the subject 50 is attached to the output unit 21 provided at the tip of the optical fiber 20. An optical image of the affected part or the like by the observation optical system is picked up by the image pickup element 42 in the camera head, transmitted to the image signal processing unit 41 via the cable 43, and signal processed by the signal processing circuit of the image signal processing unit 41, A video signal is generated and output to a television monitor so that an endoscopic image of the affected area can be displayed.

The camera head provided with the image sensor 42 is provided so as to be able to move substantially integrally with the output unit 21. However, it is preferable to prevent the illumination light 2 emitted from the output unit 21 from directly entering the image sensor 42.
The image sensor 42 is a general term for electronic components (light receiving elements) that convert an optical image of the subject 50 into an electrical signal. CCDs (charge-coupled devices) are widely used in digital cameras, but those using CMOS (CMOS image sensors) are beginning to be used.

<Second Embodiment>
<Light emitting device>
The light emitting device according to the second embodiment emits the excitation light source 10 that emits the excitation light 1 and the excitation light 1 emitted from the excitation light source 10 and converts the wavelength to emit the illumination light 2 in a predetermined wavelength range. And the optical fiber 20 that guides the illumination light 2 emitted from the wavelength conversion member 30 to the outside. Description of the light emitting device according to the first embodiment that has substantially the same configuration is omitted.

In the light emitting device according to the second embodiment, the position of the fluorescent material 31 that is the wavelength conversion member 30 is changed.
The fluorescent material 31 can be provided in the emission part 12 provided in the excitation light source 10. The light emitted from the light emitting element 11 passes through the lens 13 and is condensed on the emission unit 12. The wavelength of the condensed light is converted by the fluorescent material 31 provided in the emission unit 12. The wavelength-converted illumination light 2 is transmitted through the optical fiber 20 to emit the illumination light 2 to the outside.
Further, the fluorescent material 31 can be provided on the lens 13 provided in the excitation light source 10. Since the illumination light 2 that has been wavelength-converted by the fluorescent material 31 provided on the lens 13 is condensed on the emission unit 12 by the function of the lens 13, color variation is not particularly problematic. Moreover, since it is not necessary to make the thing which mixed the fluorescent substance 31 with resin other than making the lens 13, a light-emitting device can be manufactured cheaply.

  A fluorescent material 31 may be provided on a part of the optical fiber 20. Since almost all of the excitation light 1 emitted from the light emitting element 11 enters the optical fiber 20, the wavelength can be converted in the optical fiber 20. The optical fiber 20 can be manufactured by mixing the fluorescent material 31 in the portion corresponding to the core.

<Third Embodiment>
<Light emitting device>
The luminaire according to the third embodiment includes an excitation light source unit 60 having a plurality of excitation light sources 10 mounted thereon, and an illumination light 2 in a predetermined wavelength region by absorbing and converting the wavelength of the excitation light 1 emitted from the excitation light source 10. A wavelength conversion member 30 that emits light, and an optical fiber 20 that guides the excitation light 1 emitted from a plurality of excitation light sources 10 mounted to the wavelength conversion member 30. A light emitting element 11 such as a laser diode is used as the excitation light source 10, and a fluorescent material 31 is used as the wavelength conversion member 30. Description of the light emitting device according to the first embodiment that has substantially the same configuration is omitted.

The excitation light source unit 60 is equipped with a plurality of excitation light sources 10. The excitation light source unit 60 includes the excitation light source 10 and an electronic circuit (not shown). The electronic circuit controls on / off of power input and controls the amount of power input.
The excitation light source unit 60 is provided with a plurality of optical fibers 20. Each of the plurality of optical fibers 20 is connected to the excitation light source 10.

An output unit 21 on which a fluorescent material 31 is mounted is provided at the tip of the optical fiber 20. The fluorescent substance 31 is wavelength-converted by the excitation light 1 of the light emitting element 11 and can emit light having various colors in addition to the three primary colors of blue, green, and red.
Here, one excitation light source 10 may be provided with a plurality of emission units 12 and a plurality of optical fibers 20 connected to the emission units 12. As the light emitting element 11, an element having excellent directivity characteristics such as a laser diode is used. The excitation light 1 emitted from the light emitting element 11 passes through the lens 13 and is sent to the emission unit 12. The excitation light 1 is collected by the lens 13. Therefore, by moving the lens 13 included in the excitation light source 10, the excitation light 1 is sent to any one of a plurality of emission units 12 provided at a predetermined position. The excitation light 1 that has been sent passes through the optical fiber 20 and irradiates the fluorescent material 31 to emit the illumination light 2 to the outside. Accordingly, the excitation light 1 can be sent to the plurality of optical fibers 20 and the fluorescent materials 31 by one excitation light source 10.

  The luminaire according to the third embodiment can be used in places where a point light source is required or where it is difficult to replace the light source. Since the location where the illumination light 2 is emitted and the excitation light source 10 can be arranged apart from each other, the excitation light source 10 can be easily replaced. Further, by using the optical fiber 20, it is possible to provide a lighting apparatus having high excitation efficiency without light attenuation on the excitation light source 10 side and the output unit 21 side.

<Example 1>
Example 1 manufactures a light emitting device according to the present invention. FIG. 1 is a schematic configuration diagram showing a light emitting device according to the present invention. FIG. 4 is a diagram showing an emission spectrum of the light emitting device according to Example 1.
The light emitting device includes an excitation light source 10, an optical fiber 20, and a wavelength conversion member 30.
As the excitation light source 10, a laser diode element 11 having a light emission peak wavelength in the vicinity of 405 nm is used. The laser diode element 11 is a GaN-based semiconductor element.
As the optical fiber 20, a quartz optical fiber 20 is used. The core diameter is 114 μm.

A fluorescent material 31 is used as the wavelength conversion member 30. The fluorescent material 31 uses Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu, Lu ₃ Al ₅ O ₁₂ : Ce, and (Ca, Sr) ₂ Si ₅ N ₈ : Eu. These fluorescent materials 31 are kneaded in the silicone resin until uniform. In order to block light in the vicinity of 405 nm emitted from the laser diode element 11, a light absorber serving as a blocking member can be mixed with the fluorescent material 31 in the resin.

  The excitation light 1 emitted from the laser diode element 11 passes through the lens 13 and is condensed on the emission unit 12. The emission unit 12 is connected to the optical fiber 20, and the excitation light 1 emitted from the excitation light source 10 is transmitted to the output unit 21 through the optical fiber 20. The output unit 21 is coated with a fluorescent material 31 contained in a silicone resin.

The illumination light 2 output from the output unit 21 has an emission spectrum as shown in FIG. This light emitting device emits white light, has an average color rendering index (Ra) of 80 or more, and particularly has a high special color rendering index (R9) indicating a red color chart.
Thereby, a light emitting device with high color rendering properties can be provided. In addition, it is possible to provide a light-emitting device that has very little color variation and high color reproducibility.

<Example 2>
Example 2 manufactures a light-emitting device according to the present invention. FIG. 1 is a schematic configuration diagram showing a light emitting device according to the present invention. FIG. 5 is a diagram showing an emission spectrum of the light emitting device according to Example 2.
The light emitting device includes an excitation light source 10, an optical fiber 20, and a wavelength conversion member 30.
As the excitation light source 10, a laser diode element 11 having a light emission peak wavelength in the vicinity of 405 nm is used. The laser diode element 11 is a GaN-based semiconductor element.
As the optical fiber 20, a quartz optical fiber 20 is used. The core system is 114 μm.
A fluorescent material 31 is used as the wavelength conversion member 30. As the fluorescent material 31, BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn is used. These fluorescent materials 31 are kneaded in the silicone resin until uniform.

The excitation light 1 emitted from the laser diode element 11 passes through the lens 13 and is condensed on the emission unit 12. The emission unit 12 is connected to the optical fiber 20, and the excitation light 1 emitted from the excitation light source 10 is transmitted to the output unit 21 through the optical fiber 20. The output unit 21 is coated with a fluorescent material 31 contained in a silicone resin.
The illumination light 2 output from the output unit 21 has an emission spectrum as shown in FIG. This light emitting device emits green light.
Thus, a light emitting device having a predetermined color tone can be provided.

<Experimental example>
In the light source device of the present invention, the temperature characteristics of the fluorescent material used for the wavelength conversion member capable of realizing higher performance and longer life, higher output, larger luminous flux, and linearity of light output versus luminous flux were measured.
In Experimental Examples 1 to 4, first, the phosphor shown in Table 1 was mixed with a resin to form a wavelength conversion member, and the light source device of Example 1 was manufactured. In each experimental example, a silica fiber of SI114 / 125NA = 0.2 and a zirconia ferrule with a diameter of 2.5 mm were used. The wavelength of the excitation light source and the mixing ratio with the resin are as shown in Table 1.

The results of Experimental Example 1 are shown in FIGS.
According to this result, the CCA, SCA and BAM all have a relatively high temperature, with a luminance maintenance rate at 250 ° C. of 60% or more relative to room temperature and a luminance maintenance rate at 300 ° C. of 35% or more. It was confirmed that the characteristics were good. Further, regarding the linearity of the light output-light flux of the SCA and CCB, it was confirmed that the SCA has linearity up to about 130 mW. Therefore, it has been found that CCA, SCA and BAM are particularly effective in terms of linearity of light output-light flux.

  In Experimental Example 2, it was confirmed that both of the two types of fluorescent materials used were good in both temperature characteristics and light output-linearity of light flux.

The results of Experimental Example 3 are shown in FIGS.
In Experimental Example 3, in the examples of BAM: Mn, LAG, etc., the luminance maintenance rate at 250 ° C. is 50% or more with respect to room temperature, and the luminance maintenance rate at 300 ° C. is 35% or more. It was confirmed that the temperature characteristics were relatively good. Further, it was confirmed that the LAG light output-light beam linearity has linearity up to a relatively high output. Therefore, it was found that fluorescent materials such as BAM: Mn and LAG are more effective in terms of linearity of light output-light flux.

  For Experimental Examples 4 and 5, it was confirmed that any of the fluorescent materials used had good temperature characteristics and light output-linearity of light flux.

The results of Experimental Example 6 are shown in FIGS.
In Experimental Example 6, both SCESN and SESN have relatively high temperature characteristics such that the luminance maintenance rate at 250 ° C. is 70% or more with respect to room temperature, and the luminance maintenance rate at 300 ° C. is 50% or more. It was confirmed to be good. Further, it was confirmed that the linearity of these light output and light flux has a linearity up to a relatively high output. Therefore, it has been found that fluorescent substances such as SCESN and SESN are more effective in terms of linearity of light output-light flux.
That is, according to the above experimental example, it was confirmed that it is preferable to use a phosphor with good temperature characteristics from the viewpoint of realizing a light-emitting device with higher brightness regardless of other characteristics.
In particular, it was found that the combination of LAG and CaAlSiN ₃ : Eu, the combination of LAG and SCESN, and the combination of LAG and SESN are effective for the linearity of light output-light flux.

  The light-emitting device of the present invention can be used for lighting fixtures, displays, and the like. The light emitting device can also be applied to an endoscope device that images the inside of a living body.

It is a schematic block diagram which shows the light-emitting device which concerns on this invention. It is a schematic block diagram which shows the endoscope apparatus which concerns on this invention. It is a schematic block diagram which shows the lighting fixture which concerns on this invention. FIG. 3 is a graph showing an emission spectrum of the light emitting device according to Example 1. 6 is a graph showing an emission spectrum of the light emitting device according to Example 2. FIG. It is a graph which shows the temperature characteristic of the blue fluorescent substance in an experiment example. It is a graph which shows the linearity characteristic of the blue fluorescent substance in an experiment example. It is a graph which shows the temperature characteristic of the green fluorescent substance in an experiment example. It is a graph which shows the linearity characteristic of the green fluorescent substance in an experiment example. It is a graph which shows the temperature characteristic of the red fluorescent substance in an experiment example. It is a graph which shows the linearity characteristic of the red fluorescent substance in an experiment example. It is a schematic block diagram which shows the conventional endoscope apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Excitation light 2 Illumination light 3 Reflected light 10 Excitation light source 11 Light emitting element 12 Injecting part 13 Lens 20 Optical fiber 21 Output part 30 Wavelength conversion member 31 Fluorescent substance 40 Imaging member 41 Image signal processing part 42 Imaging element 43 Cable 50 Subject 60 Excitation Light source unit

Claims (18)

An excitation light source comprising a laser diode element that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
The excitation light source is provided at one end, the wavelength converting member is provided at the other end, and the refractive index of the central portion (core) of the cross section is made higher than that of the peripheral portion (cladding). An optical fiber led to the conversion member,
The wavelength conversion member includes a fluorescent material and a filler consisting of calcium chlorapatite and (CCA) in combination or barium magnesium aluminate with YAG (BAM) and Y AG, median particle with fluorescent substance and a filler The diameter difference is less than 20% with respect to the particle diameter of the fluorescent material, and the filler has a center particle diameter of 1 μm or more and less than 5 μm. An excitation light source comprising a laser diode element that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
An optical fiber for leading the illumination light emitted from the wavelength conversion member to the outside by making the refractive index of the central part (core) of the cross section higher than that of the peripheral part (cladding),
The wavelength converting member is a fluorescent material comprising a combination of lutetium aluminum garnet (LAG) and Eu activated calcium silicon nitride (CESN) or a combination of lutetium aluminum garnet (LAG) and Eu activated calcium strontium silicon nitride (SCESN). And the filler, the difference in the center particle size between the fluorescent material and the filler is less than 20% with respect to the particle size of the fluorescent material, and the filler has a center particle size of 1 μm or more and less than 5 μm. apparatus. An excitation light source comprising a laser diode element that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
The excitation light source is provided at one end, the wavelength converting member is provided at the other end, and the refractive index of the central portion (core) of the cross section is made higher than that of the peripheral portion (cladding). An optical fiber led to the conversion member,
The wavelength conversion member includes a fluorescent material and a filler consisting of calcium chlorapatite and (CCA) in combination or barium magnesium aluminate with YAG (BAM) and Y AG, circularity of the fluorescent substance and a filler The difference is less than 20% with respect to the circularity of the fluorescent material, and the filler has a center particle diameter of 1 μm or more and less than 5 μm. An excitation light source comprising a laser diode element that emits excitation light;
A wavelength conversion member that absorbs excitation light emitted from the excitation light source and converts the wavelength to emit illumination light in a predetermined wavelength range; and
An optical fiber for leading the illumination light emitted from the wavelength conversion member to the outside by making the refractive index of the central part (core) of the cross section higher than that of the peripheral part (cladding),
The wavelength converting member is a fluorescence composed of a combination of lutetium aluminum garnet (LAG) and Eu activated calcium silicon nitride (CESN), or a combination of lutetium aluminum garnet (LAG) and Eu activated calcium strontium silicon nitride (SCESN). A light emitting material including a substance and a filler, wherein a circularity difference between the fluorescent substance and the filler is less than 20% with respect to the circularity of the fluorescent substance, and the filler has a center particle diameter of 1 μm or more and less than 5 μm apparatus. Wherein the wavelength conversion member, the light emitting device according to any one of claims 1-4, containing at least a portion of the nitride fluorescent substance.   The light emitting device according to claim 1, wherein the wavelength conversion member contains at least a part of a rare earth aluminate fluorescent material.   5. The wavelength conversion member according to claim 1, wherein the wavelength conversion member contains at least a part of a fluorescent material having a luminance maintenance rate at 250 ° C. of 50% or more with respect to a luminance maintenance rate at room temperature. Light emitting device.   The light emitting device according to any one of claims 1 to 7, wherein the wavelength conversion member is mixed with a covering member constituting the wavelength conversion member.   The light-emitting device according to claim 1, wherein the excitation light source is a light-emitting element.   The light-emitting device according to claim 1, wherein the excitation light source has an emission peak wavelength from 350 nm to 500 nm.   The light emitting device according to any one of claims 1 to 10, wherein the light emitting device guides excitation light emitted from the excitation light source to an optical fiber via a lens provided between the excitation light source and the optical fiber.   The light-emitting device according to claim 1, wherein the light-emitting device has a blocking member that blocks 90% or more of light from the excitation light source in the wavelength conversion member.   The light emitting device according to any one of claims 1 to 12, wherein the light emitting device has an average color rendering index (Ra) of 80 or more.   The light-emitting device according to claim 1, wherein the fluorescent material has a particle size in a range of 1 to 20 μm.   The light emitting device according to claim 8, wherein the covering member includes inorganic glass.   The light-emitting device according to claim 1, wherein a plurality of the excitation light sources are mounted. A light emitting device according to any one of claims 1 to 16,
An endoscope apparatus comprising: an imaging member that irradiates a subject with light emitted from the light emitting device and captures a normal image of the light reflected from the subject.   The endoscope apparatus according to claim 17, wherein the imaging member is an imaging element.

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