JP2010097829A - Lighting system and vehicular lighting fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system using a white LED, which can attain efficient and stable operation while emitting near infrared light together with visible light. <P>SOLUTION: A wavelength conversion layer for converting a part of visible light emitted by a semiconductor light emitting element includes a first phosphor having an emission peak in a predetermined visible light range and a second phosphor having an emission peak in each of the predetermined visible light range and a predetermined near infrared light range. A cover member is heated by absorbing the near infrared light. Since the fluorescence of the visible light emitted by the first phosphor and the second phosphor can be used, a sufficient emission quantity can be ensured. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an illumination device using a semiconductor light emitting element (LED), and more particularly to a vehicle headlamp.

  Conventional automotive headlamps using discharge lamps and halogen lamps emit not only visible light but also infrared rays, so the front of the headlamp is heated and snow adheres to the outer cover during bad weather. Even if there was, it had the function of melting naturally.

In recent years, automotive headlights using white LEDs with high luminous efficiency have been put into practical use. This white LED is a combination of a blue LED and a yellow phosphor, and Y ₃ A ₁₅ O ₁₂ : Ce ³⁺ is used as the yellow phosphor. The advantage of headlamps using white LEDs is that they produce less heat and are highly efficient. However, they do not emit infrared rays, so the problem is that the snow and ice that accumulates on the outer cover on the front of the headlamps do not melt during bad weather. was there.

  In order to solve this problem, Patent Documents 1 to 4 disclose a configuration in which a heating component for melting snow, a heating element, and a component for controlling hot air are provided in the headlamp.

  On the other hand, Patent Document 5 proposes a light-emitting element having an emission spectrum for visible light and near-infrared light by combining an LED element with a phosphor that emits light in the visible wavelength range and a phosphor that emits light in the infrared wavelength range. ing.

  Non-Patent Document 1 discloses a YAG: Ce, Er phosphor in which Ce and Er are added to a garnet crystal structure of yttrium aluminum oxide as a phosphor having light emission in the near infrared. This phosphor is known to have light emission in the near infrared region of 1400 to 1700 nm derived from Er due to energy transfer from Ce to Er. According to Non-Patent Document 1, even when Er alone is added to a YAG crystal, the near-infrared emission of Er is weak, and bright emission is obtained when Ce is added simultaneously (FIG. 2 of Non-Patent Document 1). (D)).

  Tm, Dy, Nd, Pr, Yb, and the like are known as rare earth elements that emit near-infrared light and are trivalent elements that can replace the yttrium atom position of the YAG crystal in addition to Er. Even if these elements are added, light emission in the near infrared region can be obtained.

Japanese Patent Laying-Open No. 2004-296212 (reference numeral 9 in FIG. 1) JP 2004-314902 A (reference numeral 140 in FIG. 1) Japanese Patent Laying-Open No. 2005-190825 (reference numeral 12 in FIG. 1) Japanese Patent Laying-Open No. 2006-244848 (reference numeral 10 in FIG. 2) JP 2006-60238 A Appl Phys Lett 2007: Vol191 No15 Page151107

  However, when the configurations described in Patent Documents 1 to 4 are adopted for the automobile headlamp, the apparatus becomes large and the degree of freedom in design is reduced, and the cost is increased.

  On the other hand, when a phosphor that emits visible light and a phosphor that emits infrared light are mixed and used as described in Patent Document 5, in applications that require a large amount of light, such as a vehicle headlamp, the visible light amount And the heat generation of the phosphor are problems. This is because when a phosphor that emits visible light and a phosphor that emits infrared light are used in combination, the ratio of the phosphor that emits visible light decreases, so that a sufficient amount of visible light is secured. Becomes difficult.

  In general, the difference between the excitation wavelength of the phosphor and the fluorescence wavelength is called a Stokes shift, and the energy loss of the phosphor increases as the shift amount increases. Therefore, a phosphor that emits infrared light has a large energy loss and a large amount of heat generation compared to a phosphor that emits visible light. Since the phosphor generally has a characteristic (temperature quenching) in which the conversion efficiency decreases due to a temperature rise, if the phosphor emitting infrared light generates heat and accumulates heat, it leads to temperature quenching. The temperature quenching of the phosphor causes a change in the chromaticity of the white light of the white LED. In automobile headlamps, the chromaticity range is determined by laws and regulations, so a change in chromaticity is a big problem. Even if the phosphor described in Non-Patent Document 1 is used instead of the mixture of the visible light phosphor and the infrared light phosphor disclosed in Patent Document 5, the problem of heat generation due to the securing of the light amount and the Stokes shift similarly occurs.

  The objective of this invention is providing the illuminating device using white LED which can implement | achieve highly efficient and stable operation | movement, emitting near infrared light with visible light.

In order to achieve the above object, according to the present invention, an illumination having a semiconductor light emitting element that emits visible light and a wavelength conversion layer that includes a phosphor that emits fluorescence by absorbing part of the light emitted by the semiconductor light emitting element. The phosphor is a first phosphor that emits fluorescence having a light emission peak in a predetermined visible light region, and fluorescence having light emission peaks in a predetermined visible light region and a predetermined near infrared light region, respectively. And a second phosphor that emits. Thus, by using the second phosphor that emits fluorescence in the visible light region and the near infrared light region in combination with the first phosphor that emits fluorescence only in the visible light region, near infrared light can be obtained. The cover member can be heated by being absorbed by the cover member. In addition, since the visible light fluorescence of the second phosphor as well as the first phosphor can be used, a sufficient visible light amount can be obtained.
The predetermined near-infrared light region of the second phosphor is preferably configured to overlap at least part of the near-infrared light absorption band of the material constituting the cover member. Thereby, a cover member can be heated efficiently.

  For example, the wavelength of light emitted from the semiconductor light emitting element is set to a wavelength of 440 nm to 480 nm, the predetermined visible light region is set to a wavelength of 530 nm to 570 nm, and the predetermined near infrared light region is set to a wavelength of 1150 nm to 2000 nm.

  For example, the wavelength conversion layer can have a two-layer structure of a first layer disposed so as to be in contact with the semiconductor light emitting element and a second layer outside the first layer. The first layer contains the second phosphor, and the second layer contains the first phosphor. As a result, the heat of the second phosphor caused by the Stokes shift can be exhausted through the semiconductor light emitting element, so that temperature quenching can be prevented and stable light emission can be obtained.

  Further, for example, the wavelength conversion layer may be configured by mixing phosphor particles in a resin, and at least a part of the second phosphor particles may be disposed so as to be in direct contact with the semiconductor light emitting device. Is possible. Accordingly, the heat of the second phosphor caused by the Stokes shift can be exhausted through the semiconductor light emitting element, and stable light emission can be obtained.

  As the second phosphor, for example, an oxide of Y and Al having a garnet structure and one or more elements of Er, Tm, Dy, Nd, Pr, Yb and Ti, and Ce Use the added one.

  For example, as a material for the cover member, a resin having an absorption band in near infrared light is used. Alternatively, a resin containing a compound having an absorption band in near infrared light is used.

  According to another aspect of the present invention, the following vehicular lamp is provided. That is, it has a semiconductor light emitting element that emits visible light, a wavelength conversion layer that includes a phosphor that emits fluorescence by absorbing part of the light emitted from the semiconductor light emitting element, and a cover member that transmits visible light and emits it to the outside. In the vehicular lamp, the phosphor includes a first phosphor that emits fluorescence having a light emission peak in a predetermined visible light region, and a light emission peak in each of the predetermined visible light region and a predetermined near infrared light region. And a second phosphor that emits fluorescence. The predetermined near-infrared light region overlaps at least a part of the near-infrared light absorption band of the material constituting the cover member. Accordingly, the near infrared light can be absorbed by the cover portion and heated while securing a sufficient amount of visible light fluorescence.

  ADVANTAGE OF THE INVENTION According to this invention, the illumination apparatus using white LED which can implement | achieve highly efficient and stable operation | movement can be provided, emitting near infrared light with visible light. Thereby, the cover of an illuminating device can be heated with near-infrared light, and a snow melting function can be provided without providing a special heating mechanism. In addition, a sufficient visible light amount can be obtained.

  Hereinafter, an automotive headlamp using an LED lighting device according to an embodiment of the present invention will be described.

  The LED illumination device of the present embodiment includes a light emitting element (LED element) that emits blue light (wavelength 440 to 480 nm), and a first light that emits yellow fluorescence (peak wavelength 530 to 570 nm) using blue light as excitation light. A combination of a phosphor and a second phosphor that emits yellow fluorescence and near-infrared fluorescence (peak wavelength: 1150 to 2000 nm) using blue light emission as excitation light, and mixes blue and yellow light to produce white light. Get. Near-infrared light emitted from the second phosphor is absorbed by the cover of the automotive headlamp and heats the cover. The second phosphor generates heat due to the Stokes shift. In this embodiment, the second phosphor has a structure that efficiently exhausts this heat.

  FIGS. 1A and 1B are a front view and an A-A ′ cross-sectional view, respectively, of the automotive headlamp of the present embodiment. The automotive headlamp includes a high beam 7, three low beams 8, a fog lamp 11, a direction indicator 10, and a position lamp 9, and the front surface thereof is covered with an outer cover 23.

  The high beam 7 and the three low beams 8 are LED illumination devices that use the LED light emitting device 6 as a light source. The high beam 7 includes four LED light emitting devices 6, a heat sink (not shown) on which the LED light emitting devices 6 are mounted to exhaust the heat, a reflecting mirror 7 a, and an optical system 7 b. Each of the three low beams 8 includes one LED light emitting device 6, a reflecting mirror 8a, and an optical system 8b such as a lens.

  The configuration of the LED light-emitting device 6 will be described with reference to a cross-sectional view in FIG. The substrate 20 is provided with a pair of electrodes 5 on which the LED element 1 is mounted. The LED element 1 includes electrode pads (not shown) on the lower surface and the upper surface, the lower electrode pads are bonded to one of the pair of electrodes 5 by solder or the like, and the upper electrode pad is bonded to the other of the pair of electrodes 5 by a bonding wire 21. It is connected. On the upper surface of the LED element 1, a dome-shaped wavelength conversion layer 22 formed of a resin 2 containing two types of phosphor particles 3 and 4 is disposed.

  The emission wavelength range of the LED element 1 is not less than 440 nm and not more than 480 nm. The resin 2 is transparent to blue light in the above wavelength range emitted from the LED element 1. For example, a silicone resin can be used.

  Of the two types of phosphor particles contained in the wavelength conversion layer 22, the first phosphor particles 3 emit yellow fluorescence (peak wavelength: 530 nm or more and 570 nm or less) using blue light as excitation light. The second phosphor particles 3 emit visible and near-infrared fluorescence, the wavelength range of visible light is yellow (peak wavelength of 530 nm or more and 570 nm or less), and the wavelength range of near-infrared light is the outer cover 23. It is designed to overlap at least partly with the absorption wavelength.

  In the present embodiment, the outer cover 23 is made of polycarbonate, which is a general cover for automobile headlamps and has high transparency and excellent weather resistance. A general polycarbonate has strong absorption in the vicinity of 1650 nm as shown in the near-infrared transmittance measurement result of FIG. This is peculiar to the carbonyl compound contained in the polycarbonate resin. Moreover, the absorption spectrum of water is as FIG. 4, and absorbs near infrared rays of 1100 nm or more.

  Therefore, the wavelength range of the near infrared light of the second phosphor particles 4 is desirably 1100 nm or more, and particularly preferably has a peak in the vicinity of 1650 nm. In the present embodiment, the second phosphor particles 4 that emit not only yellow light but also near infrared light of 1150 nm to 2000 nm are used. Thereby, the outer cover 23 can be heated with near-infrared light, and the malfunction by the adhesion of snow and ice in bad weather can be eliminated.

As the first phosphor particles 3, YAG (Y ₃ Al ₅ O ₁₂ ) -based phosphor particles such as YAG: Ce can be used. As the second phosphor particle 4, a phosphor in which Ce and Er are added to a YAG crystal, such as YAG: Ce, Er, can be used. This phosphor emits light in the near-infrared region of 1400 nm to 1700 nm derived from Er by energy transfer from Ce to Er. Further, in place of Er, a trivalent element Tm, Dy, Nd, Pr, or Yb capable of substituting the yttrium atom position of the YAG crystal can be added. Even when these elements are added, light emission can be obtained in the near infrared region.

  The second phosphor particles 4 have a large Stokes shift (difference between the excitation wavelength and the fluorescence wavelength) because visible light is used as excitation light and fluorescence of visible light and near infrared light is emitted. For this reason, the second phosphor 4 has a larger energy loss and a larger amount of heat generation than the first phosphor particles 3. Therefore, in the present embodiment, the wavelength conversion layer 22 is configured so that the second phosphor particles 4 are in direct contact with the LED element 1 or are close to each other through the thin resin 2. Specifically, the wavelength conversion layer 23 is divided into a lower layer in contact with the LED element 1 and an upper layer mounted thereon, and the lower layer contains only the second phosphor particles 4; The upper layer contains only the first phosphor particles 3. Thereby, since the heat generated by the second phosphor particles 4 can be efficiently exhausted to the heat sink on which the substrate 20 is mounted via the LED element 1 and the substrate 20, the phosphor 4 and the phosphor 3 are heated to a high temperature. Can be prevented and temperature quenching can be prevented. Further, by smoothing the exhaust heat, the temperature rise of the LED element 1 can be suppressed, and the LED lighting device 6 can be highly efficient, highly stable, and highly reliable.

  The LED light emitting device 6 including the wavelength conversion layer 22 having such a two-layer structure can be manufactured as follows.

  First, a substrate 20 provided with an electrode 5 in advance is prepared, and a separately manufactured blue LED element 1 is joined to one electrode 5 with solder or the like. The electrode pad on the upper surface of the LED element 1 and the other electrode 5 are wire-bonded by a wire 21.

  The first phosphor particles 3 and the second phosphor particles 4 are respectively dispersed in a resin material at a predetermined ratio. First, a predetermined amount of a resin material in which the second phosphor particles 4 are dispersed is dropped onto the upper surface of the LED element 1 using a dispenser or the like to form a coating film, and then cured by heating or the like. Thereby, the lower layer of the wavelength conversion layer 22 in which the second phosphor particles 4 are dispersed is formed. Thereafter, a predetermined amount of a resin material in which the first phosphor particles 3 are dispersed is dropped on the lower layer to form a coating film that is raised by surface tension, and then cured by heating or the like. Thereby, the upper layer of the wavelength conversion layer 22 in which the first phosphor particles 3 are dispersed is formed. Thus, the LED light emitting device 6 is manufactured. The LED light emitting device 6 is mounted on a heat sink, and the high beam 7 and the low beam 8 (LED illumination device) are assembled by combining with the reflecting mirrors 7a and 8a and the optical systems 7b and 8b.

  The high beam 7 and the low beam 8, the position lamp 9, the direction indicator 10, the fog lamp 11 and the like are arranged at predetermined positions in FIG. 1, and the outer cover 23 is attached to complete the automotive headlamp.

  In the automotive headlamp of the present embodiment, when the LED elements 1 of the high beam 7 and the low beam 8 are turned on, blue light is emitted and passes through the wavelength conversion layer 22. Part of the blue light excites the second phosphor particles 4 and the first phosphor particles 3, and yellow fluorescence (peak wavelength 530 to 570 nm) and near infrared light are emitted from the second phosphor particles 4. Of fluorescence (peak wavelength 1150-2000 nm) is emitted. Yellow fluorescence is emitted from the first phosphor particles 3.

  The yellow fluorescence emitted from the first and second phosphor particles 3 and 4 is mixed with the blue light transmitted through the wavelength conversion layer 22 to become white light. The white light passes through the optical systems 7b and 8b, passes through the outer cover 23, and is irradiated to the front of the automobile. As is clear from the transmission spectrum shown in FIG. 3, the material constituting the outer cover 23 (polycarbonate) has little absorption of visible light, so that white light passes through the outer cover 23 almost without being absorbed.

  Near-infrared fluorescence (peak wavelength 1150 to 2000 nm) emitted from the second phosphor particles 4 passes through the optical systems 7 b and 8 b and further enters the outer cover 23. Since the material constituting the outer cover 23 has a property to absorb light in the near-infrared region of 1000 nm or more with an absorption peak near 1670 nm as in the transmission spectrum of FIG. 3, most of the fluorescence of the near-infrared light is outer. Absorbed by the cover 23. Thereby, the outer cover 23 is heated and the snow and ice adhering to the outer cover 23 can be melted. Further, since water itself absorbs near-infrared light having a wavelength of 900 nm or more as shown in the transmission spectrum of FIG. 4, snow and ice itself are directly heated and melted by the near-infrared light emitted from the second phosphor particles 4. A dull action is also obtained.

  As described above, according to the present embodiment, by combining the first phosphor that emits visible light and the second phosphor that emits visible light and near-infrared light, the front of an automobile using an LED as a light source is combined. Although it is an illumination lamp, the outer cover can be heated without providing a special structure such as a heating element, and a snow melting function can be provided.

  In addition, in the present embodiment, the second phosphor particles 4 that emit visible light and near-infrared light are disposed close to the LED element 1, and the first phosphor particles 3 are disposed outside the second phosphor particles 4. As a result, the heat generation of the second phosphor particles 4 caused by the Stokes shift can be efficiently released to the heat sink via the LED element 1 and the substrate 20. A decrease in luminous efficiency can be prevented.

  In the present embodiment, the second phosphor particles 4 are not simply phosphors that emit near-infrared light, but phosphors that emit both near-infrared light and visible light. Thereby, the yellow fluorescence emitted from the first phosphor particles 3 and the yellow fluorescence emitted from the second phosphor particles 4 can be combined to obtain yellow fluorescence with a sufficient amount of light. Therefore, even in the case of a white LED that requires a large amount of light, such as an automobile headlamp, heating of the outer cover by infrared light and visible light color conversion can both be achieved.

  At this time, since the wavelength conversion layer 22 has a dome shape and does not have an end face, the light from the semiconductor light emitting element 1 is raised in the front direction and emitted. As a result, the luminance distribution on the front surface of the semiconductor light emitting element 1 also has an effect that the rising of the irradiation region from the non-irradiation region becomes steep.

  In the above-described embodiment, when the wavelength conversion layer 22 is formed, a method of dropping a resin material on the LED element 1 is used. However, the present invention is not limited to this method, and other methods can be used. . For example, a printing process such as screen printing or stencil printing can be used. In this case, first, the resin material added with the second phosphor particles 4 is printed on the LED element 1 to form the lower layer 22a of the wavelength conversion layer 22 as shown in FIG. By printing the resin material to which the phosphor particles 3 are added to form the upper layer 22b, the wavelength conversion layer 22 in which the second phosphor particles 4 are arranged close to the LED element 1 can be formed.

  As yet another method, the first phosphor particles 3 and the second phosphor particles 4 are mixed in a resin material, dropped onto the LED element 1, and the second phosphor particles 4 are first settled. Accordingly, it is possible to form the wavelength conversion layer 22 in which the second phosphor particles 4 are gathered in the lower layer. In this case, the surface of the second phosphor particles is preliminarily coated or microencapsulated so that the second phosphor particles 4 settle before the first phosphor particles 3. Is possible.

  Although the LED light-emitting device 6 of this embodiment was the structure provided with only one LED element 1, it can be set as the structure provided with a some LED element. Thereby, the temperature rise of the outer cover 23 can be expected.

  Moreover, although the thing made from a normal polycarbonate was used as the outer cover 23 used this time, it is also possible to contain compounds, such as dye which has absorption in the near infrared part of 1450-1700 nm. Since the absorption of near-infrared light by the dye is added to the absorption of near-infrared light of the polycarbonate itself, a more efficient temperature rise can be expected.

  The automotive headlamp according to the present embodiment does not require the introduction of wind guide parts and heat generating parts and its control system as in the prior art, and can achieve a snow melting function by heating the outer cover 23 with a simple structure. I can do it.

  The present invention can be applied to general lighting devices in addition to LED light emitting devices and vehicle lighting devices using the LED light emitting devices.

  Examples of the present invention will be described below. In this example, phosphor particles emitting only visible light and phosphor particles emitting visible light and near-infrared light were produced, and their compositions and optical properties were examined. Furthermore, the LED light-emitting device 6 and the automotive headlamp of FIG. 2 were manufactured using these phosphor particles, and the temperature rise of the outer cover was measured. Details will be described below.

<Manufacture of phosphor particles>
As starting materials, powders of yttrium oxide (purity 4N), α-type alumina (purity 2N), cerium oxide (purity 4N), erbium oxide (purity 3N), and barium fluoride (purity 2N) as flux were prepared. These were weighed at the blending ratios of Samples 1 to 5 in Table 1, respectively.

  The weighed material was placed in a cylindrical 1 L polyvinyl container together with alumina balls and ethanol, and mixed on a rotary table at 100 rpm for 5 hours. The slurry after removing the mixed alumina balls was suction filtered, put into a glass beaker, and dried in a drying oven at 100 ° C. for 15 hours.

  After drying, it was pulverized in an alumina mortar, passed through a # 300 nylon mesh, and the resulting powder was placed in an alumina crucible and placed in a firing furnace. In order to perform firing in a reducing atmosphere, the inside of the furnace was evacuated to 20 Pa with a mechanical booster pump before firing, and then nitrogen gas containing 4% of hydrogen (purity 4 N or more) was introduced to 0.1 MPa.

  Thereafter, baking was performed at 1500 ° C. for 2 hours. After firing, the mixture was coarsely pulverized with an alumina mortar and pestle to obtain a yellow phosphor powder through a # 300 nylon mesh. The obtained powder was washed with a 2N concentration nitric acid aqueous solution and ion-exchanged water and dried to obtain target phosphor particle samples 1 to 5 through a # 300 nylon mesh.

<Characteristic evaluation of phosphor particles>
(Crystal structure)
About the obtained phosphor particle sample 2, the crystal structure was identified using a powder X-ray diffractometer (D8 Advance manufactured by Bruker). The measurement results are shown in FIG. X-rays used for the measurement are Cu · Kα rays. From the measurement results of FIG. 6, it was confirmed that the same diffraction line pattern as that of Y ₃ Al ₅ O ₁₂ registered in ICDD (International Center for Diffraction Data) was obtained. From this, it was confirmed that Sample 2 has YAG as the main phase. In addition, since other samples 1 and 3 to 5 use the same manufacturing method, it is assumed that YAG is the main phase.

(Composition analysis)
Quantitative analysis of each element was performed on samples 1 to 5 of the phosphor particles. For quantitative analysis, a fluorescent X-ray analyzer ZSXPrimusII manufactured by Rigaku Corporation was used. The obtained results (composition) are shown in Table 1 below.

(Measurement of fluorescence characteristics)
First, the fluorescence characteristics (chromaticity x, y, visible light emission intensity) in the visible light range were measured for samples 1 to 5.

  The configuration of the fluorescence characteristic measurement system for the visible light portion is as follows. A xenon lamp was used as an excitation light source, and the emitted light was passed through a spectrometer to obtain 450 nm monochromatic light. The phosphor is irradiated with this light, and both the reflected light of the blue light and the emission of the phosphor are collected by an integrating sphere, and the emission spectrum is measured with an ultra-sensitive instantaneous multi-photometry system (MPCD-7000 manufactured by Otsuka Electronics). Measurements and chromaticity x, y and luminance were performed. The measurement of chromaticity was performed on a portion of 480 to 780 nm, in which the emission of the phosphor occupies most of the obtained emission spectrum.

  As shown in FIG. 7, the emission spectrum of Sample 2 had an emission peak in the vicinity of 550 nm in the visible light region.

  Table 2 shows the chromaticity x and y of samples 1 to 5 and the relative luminance (relative value to the luminance of sample 5).

  Next, the samples 1 to 5 were evaluated for near-infrared fluorescence characteristics. This evaluation was performed by preparing the LED light-emitting device for evaluation shown in FIG. 8 using each of samples 1 to 5, and measuring the light emission characteristics.

  As shown in FIG. 8, the evaluation LED light-emitting device has an electrode 5 in which phosphor bronze is silver-plated on a resin substrate 30 and has an emission wavelength of 450 nm and an upper surface of 0.3 mm square InGaN-based blue light-emitting LED element. 31 were joined. A lamp house 12 is mounted around the LED element 31. On the LED element 31 of this package, a paste was blended so that the phosphor particles 34 (any one of the samples 1 to 5) and the silicone resin 32 were in a weight ratio of 1: 9. The package filled with the phosphor-containing resin was placed in a heating furnace at 150 ° C. for 4 hours to cure and fix the silicone resin.

  The obtained light emitting device was supplied with a direct current of 20 mA, and the light emission characteristics (emission spectrum) were measured. The measurement was performed in a range of 250 nm to 2000 nm using a multipurpose spectroradiometer MSR • 7000N manufactured by Opto Research.

  FIG. 9 shows the emission spectrum of the evaluation LED light-emitting device using the phosphor of sample 1 as the phosphor particle 34 and the emission spectrum of the evaluation LED light-emitting device using the phosphor of sample 5 respectively. As is clear from FIG. 9, the evaluation LED light-emitting device of sample 1 has emission peaks in the visible light portion and the near-infrared light portion, whereas the evaluation LED light-emitting device of sample 5 is only in the visible light portion. It had an emission peak.

  Moreover, although the emission spectrum was not illustrated about the samples 2-4, all had the emission peak in visible light and near-infrared light. Sample 3 has the highest intensity of near-infrared light. With this as 1, the relative intensity of near-infrared light of other samples is shown in Table 2. From Table 2, the sample 4 to which no Ce was added had the lowest near-infrared light intensity.

  Samples 1, 2, 3, and 4 are blended at a molar ratio of Y: Ce: Er = 2: 1, 2: 2, 2: 3, 0: 2, respectively, and visible light increases when the Er blending ratio is increased. It can be seen that the near-infrared light is increased and the emission of visible light and infrared light are significantly reduced by adding Er alone. From the viewpoint of infrared intensity, the ratio of the combination of Ce and Er is preferably sample 2. Sample 5 is desirable in terms of visible light intensity. In order to make the emission intensity of the near-infrared light part and visible light part compatible, in this embodiment, the phosphor sample 5 that emits only visible light and the phosphor sample 2 that emits visible light and near-infrared light are combined. Use.

<Manufacture of LED light emitting device>
The LED light emitting device of FIG. 1 was manufactured by combining the phosphor of sample 5 and the phosphor of sample 2 that emits visible light and near infrared light.

  An InGaN-based blue light-emitting LED element 1 having an emission wavelength of 450 nm and an upper surface of 0.9 mm square was bonded to the ceramic substrate 20 on which the electrodes 5 were previously arranged, thereby manufacturing a package. Sample 2 was prepared as phosphor particle 4 and sample 5 was prepared as phosphor particle 3, and each was mixed with a silicone resin material. The weight ratio between the phosphor particles and the silicone resin was adjusted to be 3: 7. A silicone resin material containing the phosphor of Sample 2 was applied onto the LED element 1 using a dispenser. On top of this, a silicone resin material containing the phosphor of Sample 5 was applied. The package was heated in a heating furnace at 150 ° C. for 4 hours. Thereby, the silicone resin 2 was cured and fixed, and the wavelength conversion layer 22 including the phosphor of the sample 2 in the lower layer and the phosphor of the sample 5 in the upper layer was formed. This manufactured the LED light-emitting device of the Example.

  Further, as a comparative example, an LED light-emitting device 6 in which the wavelength conversion layer 22 was formed by applying only the phosphor-blended silicone resin material of Sample 5 was manufactured.

<Evaluation of LED light emitting device>
A 700 mA direct current was passed through the obtained LED light emitting device 6 to measure the light emission characteristics. For measurement in the visible light region, chromaticity measurement was performed using a spectrophotometer DA-2100 manufactured by Labsphere. The obtained chromaticity was (x, y) = (0.318, 0.347) and was a value falling within the headlight chromaticity standard of SAE (Society of Automobile Engineers).

  For the infrared region, the emission spectrum and axial output were measured using MCPD-5000 manufactured by Otsuka Electronics. FIG. 10 shows emission spectra in the infrared region of the LED light emitting devices of the example and the comparative example. Since the LED light-emitting device 6 of Example contains the phosphors of Sample 2 and Sample 5, many emission spectra derived from Er were observed in the infrared region (1450 to 1700 nm). On the other hand, the LED light emitting device of the comparative example including only the phosphor of the sample 5 could not observe light emission in the infrared region.

<Evaluation of automotive headlamps>
Using the LED light-emitting device 6 of the above example and the LED light-emitting device of the comparative example, an automotive headlamp having the configuration of FIG. 11 including the reflecting mirror 13 and the polycarbonate outer cover 23 was manufactured.

  Thermocouples were disposed outside and inside the outer cover 23. A 700 mA direct current was passed through the LED light emitting device 6 and the temperature rise of the outer cover 23 was measured. The measurement was performed in a dry state where the outer cover 23 did not adhere to water or ice. The measurement results are shown in FIG.

  In the automotive headlamp using the LED light emitting device 6 including the two types of phosphor particles of the sample 2 and the sample 5 of this example, the temperature inside and outside the cover 23 rose, but only the phosphor of the sample 1 emitted the LED. The temperature rise is small in the automotive headlamp.

  Although the LED light-emitting device 6 used for the measurement of the present embodiment has a configuration including only one LED element 1, an actual automotive headlamp often includes a plurality of LED elements, and the LED light-emitting device. 6 is almost sealed by the cover 23, so that a further temperature rise of the cover 23 can be expected.

The (a) front view and (b) A-A 'sectional view of the automotive headlamp of this embodiment. Sectional drawing of the LED light-emitting device 6 used for the vehicle headlamp of FIG. The graph which shows the near-infrared region transmission spectrum of a polycarbonate. The graph which shows the near infrared region transmission spectrum of water. Sectional drawing of the LED light-emitting device 6 which comprised the wavelength conversion layer by printing of this embodiment. The graph which shows the X-ray-diffraction pattern of the fluorescent substance particle (sample 2) of a present Example. The graph which shows the fluorescence spectrum of the visible region of the fluorescent substance particle (sample 2) of a present Example. Sectional drawing of the LED light-emitting device for evaluation used for evaluation of the fluorescence characteristic of the fluorescent substance particle of an Example. The graph which shows the emission spectrum of the LED light-emitting device for evaluation which used the fluorescent substance particle for the sample 2 and the sample 5, respectively. The graph which shows the infrared region emission spectrum of the LED light-emitting device (sample 2 + sample 5) of an Example, and the LED light-emitting device (sample 5 only) of a comparative example. Sectional drawing which shows the structure of the automotive headlamp of an Example. The graph which shows the temperature rise of the outer cover of the headlamp for motor vehicles of an Example and a comparative example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... LED element, 2 ... Resin, 3 ... 1st fluorescent substance, 4 ... 2nd fluorescent substance, 5 ... Electrode, 6 ... LED light-emitting device, 7 ... High beam, 7a ... Reflector, 7b ... Optical system, 8 ... Low beam, 8a ... Reflector, 8b ... Optical system, 9 ... Position lamp, 10 ... Direction indicator, 11 ... Fog lamp, 13 ... Reflector, 20 ... Substrate, 21 ... Wire, 22 ... Wavelength conversion layer, 22a ... Bottom Side layer, 22b ... upper layer, 23 ... outer cover, 30 ... substrate, 31 ... LED element, 32 ... silicone resin, 34 ... phosphor, 35 ... electrode.

Claims (9)

A semiconductor light emitting element that emits visible light, and a wavelength conversion layer that includes a phosphor that emits fluorescence by absorbing a part of the light emitted by the semiconductor light emitting element,
The phosphor has a first phosphor that emits fluorescence having a light emission peak in a predetermined visible light region, and a second phosphor that emits fluorescence having a light emission peak in each of the predetermined visible light region and a predetermined near infrared light region. And a phosphor. The illumination device according to claim 1, further comprising a cover member that transmits visible light emitted from the semiconductor light emitting element and the wavelength conversion layer and emits the visible light to the outside.
The lighting device according to claim 1, wherein the predetermined near-infrared light region of the second phosphor overlaps at least a part of a near-infrared light absorption band of a material constituting the cover member.   3. The lighting device according to claim 1, wherein the wavelength conversion layer has a two-layer structure of a first layer disposed so as to contact the semiconductor light emitting element and a second layer outside the first layer. The lighting device, wherein the first layer contains the second phosphor, and the second layer contains the first phosphor.   3. The illumination device according to claim 2, wherein a wavelength of light emitted from the semiconductor light emitting element is a wavelength of 440 nm to 480 nm, and the predetermined visible light region of the fluorescence is a wavelength of 530 nm to 570 nm, The infrared light region has a wavelength of 1150 nm to 2000 nm.   5. The illumination device according to claim 1, wherein the wavelength conversion layer has a configuration in which particles of the phosphor are mixed in a resin, and at least a part of the particles of the second phosphor is formed. The lighting device is arranged so as to be in direct contact with the semiconductor light emitting element.   6. The lighting device according to claim 1, wherein the second phosphor is an oxide of Y and Al and has a garnet structure as a crystal structure, and Er, Tm, Dy, Nd, Pr, A lighting device, wherein one or more elements of Yb and Ti and Ce are added.   The lighting device according to any one of claims 1 to 6, wherein the material of the cover member is a resin having an absorption band in near infrared light.   The lighting device according to any one of claims 1 to 7, wherein a material of the cover member is a resin containing a compound having an absorption band in near infrared light. A semiconductor light emitting element that emits visible light; a wavelength conversion layer that includes a phosphor that emits fluorescence by absorbing a part of the light emitted from the semiconductor light emitting element; and a cover member that transmits the visible light and emits it to the outside. Have
The phosphor has a first phosphor that emits fluorescence having a light emission peak in a predetermined visible light region, and a second phosphor that emits fluorescence having a light emission peak in each of the predetermined visible light region and a predetermined near infrared light region. Phosphors, and
The vehicle lamp according to claim 1, wherein the predetermined near-infrared light region overlaps at least a part of a near-infrared light absorption band of a material constituting the cover member.

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