Lighting apparatus

Abstract

This lighting apparatus is provided with a blue LED chip having a maximum peak at a wavelength of 420-480 nm and a fluorescent material-containing resin layer disposed on the front of the blue LED chip in the light emission direction. The fluorescent material-containing resin layer is obtained by mixing and dispersing a LuAg fluorescent material, which is represented by the formula Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ and in which the Ce activation rate is 2 mol. % or lower relative to Lu, and a double fluoride fluorescent material represented by the formula A.sub.2(B.sub.1xMn.sub.x)F.sub.6 (in the formula, A is at least one type of element selected from among the group consisting of Li, Na, K and Cs, B is at least one type of element selected from among the group consisting of Si, Ti, Nb, Ge and Sn, and x is an integer that falls within the range 0.001x0.1) in a resin. The present invention is capable of achieving a higher sense of brightness, high visibility and a sense of brightness across a wide range under scotopic conditions or mesopic conditions with an emitted light color close to black body radiation.

Claims

1. A lighting apparatus comprising a blue LED chip having maximum peak at a wavelength of 420 to 480 nm and a phosphor-containing resin layer disposed in front of the blue LED chip in its emission direction, wherein the phosphor-containing resin layer comprises an LuAG phosphor having the following compositional formula (1):
Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+(1) and a Ce activation rate in relation to Lu of up to 2 mol %, and a complex fluoride phosphor having the following compositional formula (2):
A.sub.2(B.sub.1xMn.sub.x)F.sub.6(2) wherein A is at least one element selected from the group consisting of Li, Na, K, and Cs; B is at least one element selected from the group consisting of Si, Ti, Nb, Ge, and Sn; and x is a positive number satisfying 0.001x0.1, and the LuAG phosphor and the complex fluoride phosphor are added and dispersed in a resin, wherein the lighting apparatus is a remote phosphor type in which the phosphor-containing resin layer is spaced apart from the blue LED package via a gas or vacuum layer and emits light having an emission spectrum, and a ratio S1/S2 of intensity S1 of a broad emission peak near wavelength 460 to 620 nm to intensity S2 of an emission peak of an emission line spectrum near 630 nm is at least 0.5 and up to 0.9 in the emission spectrum.

2. The lighting apparatus of claim 1 wherein the resin is a silicone resin or an epoxy resin.

3. The lighting apparatus of claim 1 wherein the resin is at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, acryl resin and ABS resin.

4. The lighting apparatus of claim 1 wherein uv value of the emission color is in the range of 0.03 to +0.03.

5. The lighting apparatus of claim 1 wherein in the phosphor-containing resin layer, a weight ratio of the LuAG phosphor and the complex fluoride phosphor (LuAG phosphor)/(complex fluoride phosphor) is in a range of 1/0.1 to 1/10.

6. The lighting apparatus of claim 1 wherein the phosphor-containing resin layer comprises the LuAG phosphor in a range of at least 0.5% by weight and up to 50% by weight of the phosphor-containing resin layer and the complex fluoride phosphor in a range of at least 1% by weight and up to 40% by weight of the phosphor-containing resin layer.

7. A lighting apparatus comprising a blue LED chip having maximum peak at a wavelength of 420 to 480 nm and a phosphor-containing resin layer disposed in front of the blue LED chip in its emission direction, wherein the phosphor-containing resin layer comprises an LuAG phosphor having the following compositional formula (1):
Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+(1) and a Ce activation rate in relation to Lu of up to 2 mol %, and a complex fluoride phosphor having the following compositional formula (2):
A.sub.2(B.sub.1xMn.sub.x)F.sub.6(2) wherein A is at least one element selected from the group consisting of Li, Na, K, and Cs; B is at least one element selected from the group consisting of Si, Ti, Nb, Ge, and Sn; and x is a positive number satisfying 0.001x0.1, and the LuAG phosphor and the complex fluoride phosphor are added and dispersed in a resin, wherein the lighting apparatus is a remote phosphor type in which the phosphor-containing resin layer is spaced apart from the blue LED package via a gas or vacuum layer, and in the phosphor-containing resin layer, a weight ratio of the LuAG phosphor and the complex fluoride phosphor (LuAG phosphor)/(complex fluoride phosphor) is in a range of 1/0.1 to 1/10.

8. The lighting apparatus of claim 7 wherein the resin is a silicone resin or an epoxy resin.

9. The lighting apparatus of claim 7 wherein the resin is at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, acryl resin and ABS resin.

10. The lighting apparatus of claim 7 wherein uv value of the emission color is in the range of 0.03 to +0.03.

11. The lighting apparatus of claim 7 wherein the phosphor-containing resin layer comprises the LuAG phosphor in a range of at least 0.5% by weight and up to 50% by weight of the phosphor-containing resin layer and the complex fluoride phosphor in a range of at least 1% by weight and up to 40% by weight of the phosphor-containing resin layer.

12. A lighting apparatus comprising a blue LED chip having maximum peak at a wavelength of 420 to 480 nm and a phosphor-containing resin layer disposed in front of the blue LED chip in its emission direction, wherein the phosphor-containing resin layer consists of an LuAG phosphor having the following compositional formula (1):
Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+(1) and a Ce activation rate in relation to Lu of up to 2 mol %, a complex fluoride phosphor having the following compositional formula (2):
A.sub.2(B.sub.1xMn.sub.x)F.sub.6(2) wherein A is at least one element selected from the group consisting of Li, Na, K, and Cs; B is at least one element selected from the group consisting of Si, Ti, Nb, Ge, and Sn; and x is a positive number satisfying 0.001x0.1, and a resin, or the LuAG phosphor, the complex fluoride phosphor, a resin and an additive selected from the group consisting of silica, alumina, mica, yttria, zinc oxide, zirconia, blue pigments, green pigments, yellow pigments, and red pigments, and the LuAG phosphor and the complex fluoride phosphor are added and dispersed in the resin, and wherein the lighting apparatus is a remote phosphor type in which the phosphor-containing resin layer is spaced apart from the blue LED package via a gas or vacuum layer.

13. The lighting apparatus of claim 12 wherein the resin is a silicone resin or an epoxy resin.

14. The lighting apparatus of claim 12 wherein the resin is at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, acryl resin and ABS resin.

15. The lighting apparatus of claim 12 wherein uv value of the emission color is in the range of 0.03 to +0.03.

16. The lighting apparatus of claim 12 wherein the lighting apparatus emits light having an emission spectrum, and a ratio S1/S2 of intensity S1 of a broad emission peak near wavelength 460 to 620 nm to intensity S2 of an emission peak of an emission line spectrum near 630 nm is at least 0.5 and up to 0.9 in the emission spectrum.

17. The lighting apparatus of claim 12 wherein in the phosphor-containing resin layer, a weight ratio of the LuAG phosphor and the complex fluoride phosphor (LuAG phosphor)/(complex fluoride phosphor) is in a range of 1/0.1 to 1/10.

18. The lighting apparatus of claim 12 wherein the phosphor-containing resin layer comprises the LuAG phosphor in a range of at least 0.5% by weight and up to 50% by weight of the phosphor-containing resin layer and the complex fluoride phosphor in a range of at least 1% by weight and up to 40% by weight of the phosphor-containing resin layer.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a diagram showing the XRD profile of Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ phosphor particles obtained in Example 1.

(2) FIG. 2 shows LED luminaire manufactured in Examples and Comparative Examples. FIG. (A) is a partly cut-away plan view and FIG. (B) is a perspective view.

(3) FIG. 3 is a diagram showing the spectral profile of the emission from an LED luminaire of Example 1.

(4) FIG. 4 is a diagram showing the spectral profile of the emission from an LED luminaire of Example 2.

(5) FIG. 5 is a diagram showing the spectral profile of the emission from an LED luminaire of Comparative Example 1.

(6) FIG. 6 is a diagram for explaining the method used in evaluating visual perception of the roadway surface and its environs using the LED luminaire of Examples and Comparative Example.

(7) FIG. 7 is a diagram showing the emission spectrum (broken line) of a general white LED, and the peak wave length (555 nm) in bright place and the peak wavelength (507 nm) in dark place of human eye sensitivity.

EMBODIMENT FOR CARRYING OUT THE INVENTION

(8) Next, the lighting apparatus of the present invention is described in detail.

(9) The lighting apparatus of the present invention includes a blue LED chip having a maximum peak in the wavelength range of 420 to 480 nm. The blue LED chip may be a well-known blue LED package in which a blue LED chip, wirings, and the like are sealed with an encapsulant. Any of well-known or commercially available blue LED packages may be used. Those blue LED chips having a maximum peak at a shorter or longer wavelength than the wavelength range defined above are undesirable because the excitation efficiency of the phosphors will be extremely reduced.

(10) The lighting apparatus of the present invention also includes a phosphor-containing resin layer which is disposed in front of the blue LED chip in its emission direction. The phosphor-containing resin layer has a phosphor (LuAG phosphor) added and dispersed in a resin, the LuAg phosphor having the compositional formula (1):
Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+(1)
and a Ce activation rate relative to Lu (i.e., proportion of Ce based on the sum of Lu and Ce) of up to 2 mol % and particularly up to 1 mol %, and preferably at least 0.1 mol %. Although the content of the phosphor represented by the compositional formula (1) may vary by the distance, position, strength, and the like of the phosphor-containing resin layer where the phosphor is disposed, the content is preferably at least 0.5% by weight and up to 50% by weight.

(11) When the Ce activation rate relative to Lu exceeds 2 mol %, the proportion of 5 d.fwdarw..sup.2F.sub.7/2 transition becomes significantly higher than the proportion of 5 d.fwdarw..sup.2F.sub.5/2 transition. The peak position of emission spectrum then shifts toward the longer wavelength side, and the emission wavelength largely deviates from the visual sensitivity under scotopic or mesopic vision, resulting in lighting with poor brightness under scotopic or mesopic vision. When the Ce activation rate relative to Lu is less than 0.1 mol %, the phosphor itself has a poor absorptivity with the risk that light near wavelength 510 nm giving bright perception under scotopic or mesopic vision may become insufficient.

(12) The LuAG phosphor used herein may be prepared by well-known methods. For example, lutetium oxide, cerium oxide, and aluminum oxide in powder form may be mixed in the amounts realizing the desired composition with barium fluoride added as a flux. The powder mixture may be heated at a high temperature in air, an inert atmosphere (e.g., nitrogen), or reducing atmosphere (e.g. an inert gas partly replaced by a reducing component such as hydrogen) to form a complex oxide, which is disintegrated on a ball mill or the like to an appropriate size.

(13) The phosphor-containing resin layer used in the present invention is the one further containing a complex fluoride phosphor added and dispersed therein. The complex fluoride phosphor is represented by the following compositional formula (2):
A.sub.2(B.sub.1xMn.sub.x)F.sub.6(2)
wherein A is at least one element selected from the group consisting of Li, Na, K, and Cs; B is at least one element selected from the group consisting of Si, Ti, Nb, Ge, and Sn; x is a positive number satisfying 0.001x0.1. Although the content of the phosphor represented by the compositional formula (2) may vary by the distance, position, strength, and the like of the phosphor-containing resin layer where the phosphor is disposed, the content is preferably at least 1% by weight to up to 40% by weight of the phosphor-containing resin layer.

(14) The complex fluoride phosphor of the present invention may be prepared by a known method (see, for example, U.S. Pat. No. 3,576,756 (Patent Document 5)).

(15) The LuAG phosphor and the complex fluoride phosphor used herein are both in particulate form. From the aspect of emission efficiency, the phosphor particles preferably have an average particle size of 1.5 to 50 m. If the average particle size is less than 1.5 m, the emission efficiency of phosphor may lower, with a drop in lighting efficiency. If the average particle size exceeds 50 m, this raises no problems with respect to lighting characteristics, but a larger amount of phosphor must be used to increase the number of particles, undesirably leading to an increased cost. The phosphor particle size used in the present invention may be determined, for example, by dispersing phosphor particles in a gas or water stream and measuring their size by the laser diffraction scattering method.

(16) In the phosphor layer, a phosphor other than the LuAG phosphor represented by the compositional formula (1) and the complex fluoride phosphor represented by the compositional formula (2) may be used for the purposes of improving the tone and color rendering of the lighting apparatus as long as the objects of the invention are not impaired. Total content of the phosphors in the phosphor-containing resin layer of the present invention is preferably at least 1.5% by weight to up to 90% by weight.

(17) The resin of the phosphor-containing resin layer may be a transparent or a semi-transparent resin, and exemplary such resins include silicone resins and epoxy resins. The phosphor-containing resin layer may be formed by adding and dispersing the phosphor in an uncured resin composition, applying the resin composition to the surface of a blue LED chip or a blue LED package, and curing the resin composition. Alternatively, a phosphor-containing resin layer may be obtained by curing and molding, and this phosphor-containing resin layer may be disposed in front of a blue LED chip or a blue LED package in its emission direction.

(18) The resin of the phosphor-containing resin layer may be a thermoplastic resin selected from polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, acryl resin and ABS resin, which may be used alone or in combination of two or more. When a thermoplastic resin is used, the thermoplastic resin may be kneaded with the phosphor to disperse the phosphor in the thermoplastic resin, and then molded to obtain the phosphor-containing resin layer. This phosphor-containing resin layer may be disposed in front of the blue LED chip or the blue LED package in its emission direction.

(19) The phosphor-containing resin layer may be molded by a well-known molding method such as compression molding, extrusion molding, or injection molding. The resin may be molded to any desired shape such as a film or a thin plate and of any desired size. The shape and size of the phosphor-containing resin layer may be adequately selected depending on how the phosphor-containing resin layer is used. The phosphor-containing resin layer may typically have a thickness in a range of about 0.02 to 5 mm although the shape is not particularly limited.

(20) The phosphor-containing resin layer may contain additives other than the resin or the phosphors to the extent not adversely affecting the object of the present invention. Suitable additives include those for improving resistance to weathering such as UV-induced degradation, those for promoting light scattering, and those for coloring, and exemplary additives include silica, alumina, mica, yttria, zinc oxide, zirconia, blue pigments, green pigments, yellow pigments, and red pigments. The content of such additive is typically up to 10% by weight and preferably at least 0.01% by weight and up to 5% by weight of the phosphor-containing resin layer.

(21) Preferably, the lighting apparatus of the present invention takes the form of remote phosphor type in which the phosphor-containing resin layer is spaced apart from the blue LED package via a gas or vacuum layer. The lighting apparatus of the remote phosphor type has intensity distribution characteristics such as surface emission and a large radiation angle different from general LED lamps. In human eyeball, rod cells are scattered in the area remote from fovea centralis, and therefore, outdoor luminaires used for the night lighting preferably emit a light having the light component with the wavelength near 507 nm in the area remote from the optical axis of the lighting apparatus. Therefore, the lighting apparatus of the remote phosphor type having large radiation angle distribution is well suited for the outdoor lighting apparatus compared with the type wherein the phosphor is disposed on the blue chip.

(22) The light emitted from the lighting apparatus of the present invention (irradiation beam) is a mixture of the light emitted from a blue LED, the light emitted from an LuAG phosphor, and the light emitted from a complex fluoride phosphor, and the lighting apparatus may emit a light with the color near the black body radiation when the ratio of the phosphors used is adjusted, namely, when the ratio of the LuAG phosphor represented by the compositional formula (1) which emits light by excitement with blue light and the complex fluoride phosphor represented by the compositional formula (2) which emits light by excitement with blue light is adjusted. More specifically, the ratio of the LuAG phosphor represented by the compositional formula (1) and the complex fluoride phosphor represented by the compositional formula (2) [(LuAG phosphor):(complex fluoride phosphor)] in weight ratio is preferably 1:0.1 to 1:10, and more preferably 1:0.5 to 1:4.

(23) When the ratio S1/S2 of intensity S1 of the broad emission peak near wavelength 460 to 620 nm to intensity S2 of the emission peak of the emission line spectrum near 630 nm is at least 0.5 and up to 0.9 in the emission spectrum from the lighting apparatus of the present invention, uv corresponding to the deviation of the color emitted from the lighting apparatus from the black body radiation can be adjusted to 0.03 to +0.03. When such light-emission conditions are selected, the luminaire will be the one which emits a light having a color near white, and the light emitted will be prevented from giving an uncomfortable impression to human eyes. In addition, when the uv is adjusted to the range of 0.01 to +0.01, the luminaire will be the one having an even smaller color deviation of the emitted light from the black body radiation with the color with even more comfortable impression. When the S1/S2 is less than 0.5 or in excess of 0.9, the uv may become less than 0.03 or in excess of +0.03, and in such a case, the color of the light emitted may deviate from white to be a color unsuitable for a luminaire. More particularly, when the LuAG phosphor represented by the compositional formula (1) is solely used without the complex fluoride phosphor represented by the compositional formula (2), no peak in the emission line spectrum will be present near 630 nm, and the value of the uv will exceed 0.03, and the light emitted will be somewhat near blue or green.

(24) The lighting apparatus of the present invention complies with the change of visual sensitivity based on Purkinje effect and sufficiently contains wavelength components of the highest visual sensitivity at the scotopic and mesopic vision levels. In addition, since the color emitted is only slightly deviated from black body radiation, the light emitted from the lighting apparatus of the present invention gives favorable impression.

(25) The lighting apparatus (luminaire device) of the invention is a luminaire suitable for outdoor use, namely, an outdoor luminaires such as streetlight for installation in those areas with less brightness at night or where least light is available (where no light source is available nearby), for example, pathways, roadways, plazas, residential areas, and tunnels. It may also be used indoor if the indoor area is in a similar dark environment, because it is suitable for use in scotopic and mesopic vision conditions.

EXAMPLES

(26) Next, the present invention is described in further detail by referring to the following Examples and Comparative Examples. However, the scope of the present invention is not limited to the Examples.

Example 1

(27) Lutetium oxide (Lu.sub.2O.sub.3) powder of 99.9% purity having an average particle size of 1.0 m, aluminum oxide (Al.sub.2O.sub.3) powder of 99.0% purity having an average particle size of 0.5 m, and cerium oxide (CeO.sub.2) powder of 99.9% purity having an average particle size of 0.2 m were mixed in a Lu:Al:Ce ratio (molar ratio) of 2.97:5.0:0.03 to obtain 1,000 g of a powder mixture. To this powder mixture, 200 g of barium fluoride was added as a flux, and the mixture was thoroughly mixed. The mixture was filled in an alumina crucible and heat treated in argon gas at 1,400 C. for 10 hours. The fired product was disintegrated on a ball mill, washed with about 0.5 mol/L hydrochloric acid and then with deionized water. Subsequent solid/liquid separation and drying yielded Lu.sub.3Al.sub.5O.sub.22:Ce.sup.3+ phosphor particles (Ce activation rate in relation to Lu; 1 mol %) having an average particle size of 20 m.

(28) The result of XRD analysis of the phosphor particles is shown in FIG. 1. The diffraction pattern of main phase of the phosphor particles was coincident with the diffraction peaks of lutetium aluminum garnet phase, demonstrating that Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ containing garnet phase as its main phase was obtained.

(29) In addition, K.sub.2(Si.sub.0.97Mn.sub.0.03)F.sub.6 phosphor particles having an average particle size of 21 m were obtained according to the procedure described in U.S. Pat. No. 3,576,756 (Patent Document 5). When emission spectrum of the phosphor particles by excitement using blue light having the wavelength of 450 nm was measured, presence of multiple emission peaks centering around 630 nm was confirmed.

(30) The Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ phosphor particles and the K.sub.2(Si.sub.0.97, Mn.sub.0.03)F.sub.6 phosphor particles at a total amount of 30% by weight [the (Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ phosphor):(K.sub.2(Si.sub.0.97, Mn.sub.0.03)F.sub.6 phosphor) weight ratio being 2:1] were dispersed in a transparent epoxy resin (SpeciFix-40 kit manufactured by Marumoto Struers K.K.) to form a slurry. The slurry was added dropwise to the emissive surface of a blue LED package (NS6b083T manufactured by Nichia Corp.) and cured at 50 C. for 3 hours to obtain an LED package having a phosphor-containing resin layer having phosphor particles added and dispersed in the epoxy resin.

(31) Seven LED packages thus manufactured were placed in a rectangular aluminum chassis having an inner size of 39 mm wide, 220 mm long, and 5 mm high and connected in series. A transparent matt acrylic plate of 2 mm thick was then mounted as a protective cover at a position 25 mm from the emissive surface of the LED packages to fabricate an LED luminaire (lighting apparatus) as shown in FIG. 2. In FIG. 2, 1 is the LED package, 2 is an aluminum chassis, 3 is a protective cover, 4 is a power supply terminal, and 5 is a power switch.

(32) Spectrum of the light from the LED luminaire was measured by a spectrophotometer CL-500 (Konica Minolta, Inc.; this spectrophotometer was also used in other Examples). The result is shown in FIG. 3. The spectrum had S1/S2 of 0.79. The uv of this LED luminaire measured by a total luminous flux measurement system (total luminous flux measurement (500) system, model HalfMoon manufactured by Otsuka Electronics Co., Ltd.; this system was also used in other Examples) was +0.022.

Example 2

(33) Seven blue LED packages (XLamp LX-E Royal Blue manufactured by Cree Inc.) were placed in an aluminum chassis and connected in series as in Example 1. The Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ phosphor particles and K.sub.2(Si.sub.0.97, Mn.sub.0.03)F.sub.6 phosphor particles in Example 1 were kneaded in polycarbonate respectively in the phosphor concentrations of 1.8% by weight and 7.2% by weight, and the resulting polycarbonate compound was molded to prepare a polycarbonate plate of 2 mm thick. This polycarbonate plate was mounted as the phosphor-containing resin layer at a position 25 mm from the light emitting surface to produce an LED luminaire of remote phosphor type as shown in FIG. 2. In this embodiment, 3 in FIG. 2 is the phosphor-containing resin layer having a function as the protective cover.

(34) Spectrum of the light from the LED luminaire was measured by a spectrophotometer. The result is shown in FIG. 4. The spectrum had S1/S2 of 0.55. The uv of this LED luminaire measured by a total luminous flux measurement system was 0.018.

Comparative Example 1

(35) The procedure of Example 1 was repeated except that the phosphor particles used were solely Lu.sub.3Al.sub.5O.sub.12:Ce.sup.3+ phosphor particles to prepare an LED package having the phosphor-containing resin layer. An LED luminaire was produced by using the thus obtained LED package.

(36) The spectrum of illuminating light of the LED luminaire was measured by the spectrophotometer, with the results shown in FIG. 5. In the spectrum, S2 peak near wavelength 630 nm was not measured. The uv of this LED luminaire measured by a total luminous flux measurement system was +0.034.

(37) The LED luminaires of Examples 1 to 2 and Comparative Example 1 were respectively secured to temporary posts at a position 3 m from the asphalt road surface to prepare LED streetlights, and the LED luminaires were turned on at night by applying a voltage of 24 V. Visual perception of road surface and adjacent objects while walking from the start point (10 m from the point just under the LED luminaire) to the end point (the point just under the LED luminaire) was evaluated by a panel of 30 people. The results are shown in Table 1. The numbers in Table 1 are proportion of the people who affirmed the items in the Table, and numbers in the bracket are the number of people who affirmed the items in the Table.

(38) TABLE-US-00001 TABLE 1 Example Comparative Item 1 2 Example 1 Brightness of the space 73% (22) 87% (26) 73% (22) Less shadow 60% (18) 80% (24) 37% (11) Clear view of the central area 33% (10) 50% (15) 33% (10) Clear view of the surrounding 77% (23) 87% (26) 77% (23) area Easy color distinction 100% (30) 100% (30) 17% (5) Non-glare light source 23% (7) 90% (27) 23% (7) Visibility of white line 100% (30) 100% (30) 50% (15) on the road surface Naturalness of the luminaire 93% (28) 100% (30) 10% (3) light

(39) These results reveal that the LED luminaires of Examples 1 and 2 are equal to or better than the LED luminaire of Comparative Example 1 in every items of the evaluation, and in particular, the LED luminaires of Examples are excellent in color distinction and naturalness of the illumination light. These LED luminaires were also excellent in the brightness of the surrounding areas demonstrating excellence under scotopic and mesopic vision conditions.

(40) It was revealed that the LED luminaire of Example 1 is an excellent luminaire in that it produces effective lighting providing improved visual perception over a broader space including brightness of the overall space and brightness in the surrounding region; and the LED luminaire has an advantage for an outdoor luminaire. This LED luminaire also received high marks of satisfaction in the color recognition of the surrounding scenery and naturalness of the illumination color. The LED luminaire of remote phosphor type in Example 2, in addition to them, further provides surface emission, and due to an accordingly wide spread of illumination, non-glare lighting with less shadows was available. Since the present invention produces lighting apparatus complying with the change of visual sensitivity based on the Purkinje effect under scotopic and mesopic vision conditions, it is best suited for outdoor luminaire.

REFERENCE SIGNS LIST

(41) 1 LED package 2 Aluminum chassis 3 Protective cover or phosphor-containing resin layer 4 Power supply terminal 5 Switch