Wavelength conversion member and lighting device using the same

Abstract

To provide a wavelength conversion device and a lighting device which can suppress the generation of color unevenness in light emitted through nano antennas.SOLUTION: A lighting device includes: a tabular phosphor part having a phosphor which emits fluorescence by being excited by excitation light; and a plurality of nano antennas which are provided in a manner to form a latticed array pattern in each of a plurality of regions on one surface of the phosphor part in planner view in a direction vertical to the one surface and which are made of a metal martial or a dielectric material. The array pattern of the plurality of nano antennas in one of the plurality of regions is obtained by rotating the array pattern of the plurality of nano antennas in another region around an axis vertical to the one surface.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wavelength conversion member and an illumination device using the same. [Background technology]

[0002] There is disclosed a device that collimates emitted light using a nano-sized antenna (hereinafter referred to as a nanoantenna). For example, Patent Document 1 discloses a lighting device having a light source that emits blue light, a phosphor layer that is excited by the light emitted from the light source to emit fluorescence, and a plurality of nanoantennas provided in a lattice pattern on the upper surface of the phosphor layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-13688 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when light emitted from a lighting device such as that described in Patent Document 1 is irradiated onto a screen located away from the lighting device, fluorescent components in some wavelength ranges of the fluorescence emitted from the phosphor layer are strongly enhanced by the action of the nanoantennas, resulting in a problem of color unevenness in the light irradiated onto the screen.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a wavelength conversion device and a lighting device that can suppress color unevenness in light emitted through a nanoantenna. [Means for solving the problem]

[0006] The wavelength conversion device according to the present invention comprises a flat phosphor section including a phosphor that emits fluorescence when excited by excitation light, and a plurality of nanoantennas made of a metallic material or a dielectric material, which are arranged to form a lattice-like arrangement pattern in each of a plurality of regions on one surface of the phosphor section when viewed in a plan view from a direction perpendicular to the one surface, and the arrangement pattern of the nanoantennas in one of the plurality of regions is a pattern obtained by rotating the arrangement pattern of the nanoantennas in the other regions around an axis perpendicular to the one surface. [Brief description of the drawings]

[0007] [Figure 1] 1 is a top view of an illumination device according to a first embodiment. [Diagram 2] 1 is a cross-sectional view of a lighting device according to a first embodiment. [Diagram 3] 3 is a diagram illustrating a state in which light emitted from the illumination device according to the first embodiment is irradiated onto a screen. FIG. [Figure 4] 4 is a graph showing various diffraction lines when the emission angle of the fluorescence emitted from a phosphor section in the lighting device according to Example 1 is changed. [Diagram 5] 1 is a graph showing luminosity for light in the visible light wavelength range. [Figure 6] FIG. 4 is a top view of an illumination device according to a modified example of the first embodiment. [Figure 7] FIG. 11 is a cross-sectional view of a lighting device according to a second embodiment. [Figure 8] 10 is a graph showing the reflectance of a dielectric multilayer film for visible light in the lighting device according to Example 2. [Figure 9] 4 is a graph showing a spectrum of a phosphor in a phosphor portion with respect to excitation light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same components are designated by the same reference numerals, and the description of the same components will be omitted. EXAMPLES

[0009] [Lighting device of embodiment 1] The configuration of a lighting device 100 according to Example 1 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a top view of the lighting device 100 according to Example 1. Fig. 2 is a cross-sectional view of the lighting device 100 taken along line 2-2 in Fig. 1. Note that the left-right direction in Fig. 1 is the width direction of the lighting device 100, and the up-down direction in Fig. 2 is the height direction of the lighting device 100.

[0010] The lighting device 100 is configured to include a mounting substrate 11, a light-emitting element 12 including a light-emitting layer provided on the mounting substrate 11, and a wavelength conversion device 13 provided on the light-emitting element 12 and including a phosphor portion that receives light emitted from the light-emitting layer and emits fluorescence.

[0011] [Mounting board] First, the mounting substrate 11 will be described. The mounting substrate 11 is a flat substrate having a rectangular upper surface. The mounting substrate 11 is made of a material having high thermal conductivity and electrical insulation properties that can efficiently dissipate heat generated when the light emitting element 12 is driven, such as aluminum nitride (AlN) or aluminum oxide (Al2O3).

[0012] [Light emitting element] Next, a description will be given of the configuration of the light emitting element 12 serving as a light source. The light emitting element 12 is provided on the upper surface of the mounting substrate 11, and is a light emitting diode (LED) having a rectangular shape when viewed from above.

[0013] The light emitting element 12 includes a semiconductor structure layer 15 having a light emitting layer, a support substrate 16 disposed on the upper surface of the semiconductor structure layer 15, and a p-electrode 17 and an n-electrode 18 disposed on the lower surface of the semiconductor structure layer 15 and joined to the mounting substrate 11. In other words, the light emitting element 12 is flip-chip mounted on the mounting substrate 11.

[0014] The semiconductor structure layer 15 is a semiconductor laminate consisting of an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer (none of which are shown), each of which is mainly made of gallium nitride (GaN). When the light emitting element 12 is driven, the light emitting layer of the semiconductor structure layer 15 emits blue light having a peak wavelength of 450 nm.

[0015] The support substrate 16 is a flat substrate with a rectangular upper surface shape. The support substrate 16 is made of a material, such as sapphire (Al2O3) or GaN, that is transparent to the blue light emitted from the light emitting layer of the semiconductor structure layer 15. The upper surface of the support substrate 16 is a light emission surface through which the blue light emitted from the light emitting layer of the semiconductor structure layer 15 is emitted from the light emitting element 12.

[0016] The p-electrode 17 is an electrode electrically connected to the p-type semiconductor layer of the semiconductor structure layer 15. The p-electrode 17 is joined to a p-side wiring (not shown) formed on the upper surface of the mounting substrate 11 via a conductive joining member (not shown).

[0017] The n-electrode 18 is an electrode electrically connected to the n-type semiconductor layer via a through electrode (not shown) that vertically penetrates the light emitting layer and the p-type semiconductor layer of the semiconductor structure layer 15 and has a side surface covered with an insulator. In other words, the n-electrode 18 is electrically connected only to the n-type semiconductor layer and is insulated from the light emitting layer and the p-type semiconductor layer. The n-electrode 18 is joined to an n-side wiring (not shown) formed on the upper surface of the mounting substrate 11 via a conductive joining member (not shown).

[0018] [Wavelength conversion device] Next, a description will be given of the configuration of the wavelength conversion device 13. The wavelength conversion device 13 is a device having a wavelength conversion function that receives light emitted from the light emitting element 12 and emits fluorescence of a different wavelength. The wavelength conversion device 13 is configured to include a phosphor section 21 and a plurality of nanoantennas 22 formed on the phosphor section 21.

[0019] The phosphor section 21 is a plate-like body having a rectangular upper surface shape. The phosphor section 21 is provided on the upper surface of the supporting substrate 16 so as to overlap with the outer edge of the supporting substrate 16 of the light emitting element 12 in a plan view of the lighting device 100 seen from above.

[0020] The phosphor section 21 is made of a phosphor that emits fluorescence when excited by blue light as excitation light emitted from the light emitting element 12. The fluorescence generated from the phosphor when excited by blue light has a broad green to orange wavelength range spanning 480 to 700 nm, and has a yellow peak wavelength at 520 to 570 nm.

[0021] The phosphor section 21 is, for example, a single crystal transparent ceramic phosphor plate made of yttrium aluminum garnet (YAG:Ce) phosphor using cerium (Ce) as an activator.

[0022] The phosphor unit 21 is not limited to a phosphor plate made of a single crystal YAG:Ce phosphor, but is preferably configured to be less prone to scattering inside. Therefore, it is preferably a single-phase phosphor plate made of a single material, and in this case, it may be polycrystalline.

[0023] When the blue light emitted from the light emitting element 12 is incident on the phosphor section 21, part of the light passes through the phosphor section 21 as it is, and the other part excites the phosphor, causing the excited phosphor to emit fluorescence.

[0024] Therefore, the excitation light that has passed through the phosphor section 21 without contributing to the generation of fluorescence and the fluorescence emitted from the phosphor are emitted from the upper surface of the phosphor section 21. As a result, white light that is a mixture of the blue light and yellow fluorescence emitted from the upper surface of the phosphor section 21 is extracted from the lighting device 100.

[0025] The nanoantennas 22 are minute columnar or pyramidal protrusions of nano size. In this embodiment, the nanoantennas 22 are cylindrical structures formed on the upper surface of the phosphor section 21. A plurality of nanoantennas 22 are formed on the upper surface of the phosphor section 21, and are arranged at a predetermined period. The nanoantennas 22 are arranged at a period smaller than the peak wavelength of the fluorescence emitted from the phosphor of the phosphor section 21.

[0026] As shown in FIG. 1, the nanoantenna 22 is formed on the upper surface of the phosphor section 21 and is divided into three regions, a first region A1, a second region A2 and a third region A3, and each of the three regions has a triangular lattice arrangement pattern.

[0027] The first region A1, the second region A2 and the third region A3 each have a rectangular shape with the longitudinal direction extending in the left-right direction in FIG. 1 when viewed in a plan view from a direction perpendicular to the top surface of the phosphor section 21, and are arranged in this order along the vertical direction in FIG. 1.

[0028] The nanoantennas 22 in the first region A1 are arranged along an arrangement line AL1 to form a triangular lattice pattern. The arrangement line AL1 is a reference line for the arrangement patterns of the nanoantennas 22 in the second region A2 and the third region A3 described later.

[0029] The nanoantennas 22 in the second region A2 are arranged along an arrangement line AL2 to form a triangular lattice pattern. The arrangement line AL2 forms an angle θ A2 It has.

[0030] In other words, the arrangement pattern of the nanoantennas 22 in the second region A2 is rotated by an angle θ A2 In the lighting device 100, the pattern is rotated by an angle θ A2 is an angle other than an integer multiple of 60°, for example 19°.

[0031] The nanoantennas 22 in the third region A3 are arranged along an arrangement line AL3 to form a triangular lattice pattern. The arrangement line AL3 forms an angle θ A3 It has.

[0032] In other words, the arrangement pattern of the nanoantennas 22 in the third region A3 is rotated by an angle θ A3 In the lighting device 100, the pattern is rotated by an angle θ A3 is an angle other than an integer multiple of 60° and the angle θ A2 The angle is different from the angle θ, for example 41°.

[0033] Each of the nanoantennas 22 is formed at the same period P as one another, as shown in Fig. 2. The period P of the nanoantennas 22 is preferably smaller than the peak wavelength of the fluorescence emitted from the phosphor of the phosphor portion 21 described above, and is preferably, for example, 420 nm to 520 nm.

[0034] Moreover, each of the nanoantennas 22 has the same diameter W. The diameter W of the nanoantennas 22 is preferably, for example, 75% to 85% of the above-mentioned period P. Specifically, for example, when the period P is 500 nm, the diameter W of the nanoantennas 22 is 375 nm to 425 nm.

[0035] Moreover, each of the nanoantennas 22 has the same height H from the upper surface of the phosphor portion 21. The height H of the nanoantennas 22 is preferably, for example, 225 nm to 325 nm.

[0036] Each of the nanoantennas 22 is made of a dielectric material or a metal material. More specifically, the nanoantennas 22 are made of a material that does not easily absorb light with wavelengths in the visible light region and has a high refractive index. For example, the nanoantennas 22 are made of a transparent dielectric material such as titanium oxide (TiO2), zirconium oxide (ZrO2), niobium pentoxide (Nb2O5), lanthanum oxide (La2O3), tantalum pentoxide (Ta2O5), hafnium oxide (HfO2), or the like.

[0037] The nanoantenna 22 is preferably made of a material having a high refractive index, particularly 1.9 or more, since the scattering efficiency increases as the difference in refractive index between the nanoantenna 22 and air increases. More specifically, the nanoantenna 22 is made of a material having a plasma frequency of surface plasmon resonance, and an alloy or laminate containing the material. For example, the nanoantenna 22 is made of a metal material such as Au (gold), Ag (silver), Cu (copper), Pt (platinum), Pd (palladium), Al (aluminum), and Ni (nickel) as a material having a plasma frequency of surface plasmon resonance.

[0038] The above-mentioned period P, diameter W, height H and material of the nanoantenna 22 are all common to the nanoantenna 22 in the first region A1, the second region A2 and the third region A3.

[0039] Here, the angle-narrowing effect of light by the nanoantenna 22 will be explained. When the fluorescence reaches the upper surface of the phosphor section 21 at an angle equal to or greater than the critical angle, the fluorescence is totally reflected by the upper surface of the phosphor section 21. When total reflection occurs, an evanescent wave is generated that seeps out from the upper surface of the phosphor section 21 toward the low refractive index medium. This evanescent wave propagates along the upper surface of the phosphor section 21, in other words, along the interface between the phosphor section 21 and the air.

[0040] When the evanescent wave propagated along the upper surface of the phosphor section 21 reaches the nanoantenna 22, it is emitted in the form of visible light with the same wavelength as the fluorescence in a direction that conforms to the diffraction conditions determined by the above-mentioned period P. This phenomenon causes the fluorescence to be emitted in an angle range that conforms to the diffraction conditions, promoting a narrowing of the angle of the fluorescence emitted from the upper surface of the phosphor section 21. The narrowing of the angle of the fluorescence by the nanoantenna 22 indicates, for example, that the action of the nanoantenna 22 increases the amount of fluorescence emitted with a light distribution angle within ±30°.

[0041] 1 and 2 are merely schematic views for explaining the nanoantennas 22. The phosphor portion 21 is, for example, 1 mm square, and in this case, more nanoantennas 22 are provided than those shown in FIG.

[0042] [Suppression of color unevenness in light emitted from lighting equipment] Here, the suppression of color unevenness in the light emitted from the illumination device 100 in this embodiment will be described with reference to FIGS.

[0043] Fig. 3 is a diagram showing a schematic state when the light emitted from the illumination device 100 of this embodiment is irradiated onto a screen S located at a location away from the illumination device 100. In Fig. 3, a circular irradiation pattern IP is formed on the screen S by irradiating the light emitted from the illumination device 100. The irradiation pattern IP is a white light pattern in which blue light and yellow fluorescent light are mixed.

[0044] In addition, on the screen S, bright line patterns BP1 (dashed line in the figure), BP2 (dotted line in the figure), and BP3 (dash line in the figure) appear, with bright lines radiating out from the center of the irradiation pattern IP every 60°, overlapping with the irradiation pattern IP.

[0045] Here, the bright line patterns shown in Fig. 3 will be described with reference to Fig. 4. Each of the bright line patterns BP1, BP2, and BP3 is a fluorescent component in a specific wavelength range enhanced by the nanoantenna 22, which appears due to the arrangement of the nanoantenna 22 in the first region A1, the second region A2, and the third region A3, respectively.

[0046] FIG. 4 shows the emission angle θ of the fluorescence emitted from the upper surface of the phosphor section 21 under the diffraction condition where the diffraction orders are expressed as (m1, m2 (m1 and m2 are integers)). em 4 is a graph showing the plot of wavelengths calculated for each wavelength. In Fig. 4, a model is used in which nanoantennas 22 made of TiO2 (refractive index 2.4) are formed at a period P of 420 nm on the upper surface of a phosphor section 21 made of a YAG:Ce phosphor. Note that the emission angle θ of the fluorescence emitted in a direction perpendicular to the upper surface of the phosphor section 21 is em is set to 0°.

[0047] 4 is a region where the fluorescence generated in the phosphor part 21 and reaching the upper surface of the phosphor part 21 is enhanced by the nanoantenna 22. In particular, the region HA indicated by the two-dot chain line in the figure is a region where the fluorescence is strongly enhanced by the nanoantenna 22.

[0048] Specifically, the fluorescent components having wavelengths of 480 to 550 nm among the fluorescent light reaching the upper surface of the phosphor section 21 are emitted at an emission angle θ of 20° to 40°. em This wavelength of 480 to 550 nm corresponds to the green wavelength region of visible light. That is, in the lighting device 100, the green fluorescent component is strongly enhanced by the nanoantenna 22 when it is emitted from the upper surface of the phosphor section 21 at the above-mentioned angle.

[0049] Fig. 5 is a graph showing luminosity, which indicates the degree of intensity at which the human eye perceives light in the visible light wavelength range. As shown in Fig. 5, luminosity in the visible light wavelength range shows a tendency to peak at yellow light near 550 nm and to increase in the green to orange wavelength range.

[0050] Referring again to FIG. 3, as described above, the fluorescence generated in the phosphor section 21 is emitted from the upper surface of the phosphor section 21 at an emission angle θ of 20° to 40°. em The green fluorescent component emitted at is strongly enhanced by the nanoantenna 22.

[0051] Therefore, the green fluorescent components enhanced by the nanoantennas 22 in each of the first region A1, the second region A2 and the third region A3 appear on the screen S as bright line patterns along the arrangement direction of the nanoantennas 22 arranged in a triangular lattice pattern in each region, i.e., bright line patterns BP1, BP2 and BP3 in which bright lines radiate out every 60°.

[0052] As described above, the arrangement patterns of the nanoantennas 22 in the second region A2 and the third region A3 are patterns obtained by rotating the arrangement pattern of the nanoantennas 22 in the first region A1 at different angles around an axis perpendicular to the upper surface of the phosphor section 21. According to the lighting device 100 of this embodiment, the nanoantennas 22 have such an arrangement mode, so that color unevenness in the light emitted from the lighting device 100 can be suppressed.

[0053] Here, for example, in the lighting device 100, when the nanoantennas 22 have a uniform arrangement pattern in the first region A1, in other words, when the arrangement patterns in the second region A2 and the third region A3 are not rotated, only one bright line pattern appears on the screen S. In other words, the bright line pattern BP1, the bright line pattern BP2, and the bright line pattern BP3 appear on the screen S in a state where they overlap with each other without any shift.

[0054] When bright line patterns overlap each other in this way on the screen S, coupled with the high visibility in the visible light region shown in Fig. 5, the difference in color between the areas where the bright line patterns appear and the areas where they do not appear when viewed by the human eye becomes large. Specifically, the irradiation pattern IP is white, whereas the overlapping bright line patterns show a strong green color. Therefore, the light irradiated from the illumination device 100 to the screen S may show strong color unevenness.

[0055] According to the lighting device 100 of this embodiment, the arrangement patterns in the second area A2 and the third area A3 are offset from the arrangement pattern in the first area A1 by an angle θ A2 and angle θ A3 Since the illumination device 100 is rotated by only one angle, the arrangement directions of the nanoantennas 22 in the first region A1, the second region A2, and the third region are different from one another in a plan view of the illumination device 100 seen from above.

[0056] Therefore, the bright line pattern BP2 that appears on the screen S is rotated by an angle θ A2 Similarly, the bright line pattern BP3 that appears on the screen S is shifted from the bright line pattern BP1 by an angle θ A3 That is, the bright line pattern BP1, the bright line pattern BP2, and the bright line pattern BP3 are arranged so as not to overlap with each other on the screen S as shown in FIG.

[0057] Therefore, according to the lighting device 100 of this embodiment, by changing the arrangement of the nanoantennas 22 for each region, the bright line patterns do not overlap with each other, making color unevenness less noticeable than when the nanoantennas 22 have a uniform arrangement.

[0058] In other words, since the arrangement direction of the nanoantennas 22 differs for each region, the bright lines are finely dispersed on the screen S, making it difficult for color unevenness to occur in the light irradiated onto the screen S. Therefore, according to the illumination device 100 of this embodiment, it is possible to suppress color unevenness from occurring in the light emitted from the illumination device 100 via the nanoantennas 22.

[0059] The light emitted from the lighting device 100 of this embodiment has a similar luminous flux as the light emitted from the lighting device in the case where all the nanoantennas 22 are uniformly arranged as described above. For example, the luminous flux of the light emitted from the lighting device in the case where all the nanoantennas 22 are uniformly arranged is 231 lm / W, whereas the luminous flux of the light emitted from the lighting device 100 of this embodiment is 232 lm / W.

[0060] Therefore, according to the lighting device 100 of this embodiment, it is possible to maintain the luminous flux of the light emitted from the lighting device 100 while suppressing the occurrence of color unevenness in the light.

[0061] In the illumination device 100 of this embodiment, the three regions, the first region A1, the second region A2, and the third region A3 shown in Fig. 1 are merely examples, and the number of regions and the number of nanoantennas 22 formed in each region are not limited as long as it is possible to suppress color unevenness in the emitted light. For example, there may be only two regions, the first region A1 and the second region A2.

[0062] Also, for example, an arrangement of the first region A1, the second region A2, and the third region A3 may be regarded as one set, and multiple sets of these may be formed on the upper surface of the phosphor section 21. In this case, it is preferable that the number of each region occupying the entire region is divided as evenly as possible.

[0063] The size of each unit region is preferably such that at least 10 periods of nanoantennas 22 can be formed, and for example, each side of the unit region preferably has a length of 5 μm or more in each lattice axis direction.

[0064] In the illumination device 100 of this embodiment, the angle θ A2 is 19°, and the angle θ A3 However, if the nanoantenna 22 has a triangular lattice arrangement pattern, the angle may be any angle other than a multiple of 60 degrees, and is not limited to this. For example, the angle θ A2 is set to 5°, and the angle θ A3 may be set to 50°.

[0065] The difference in rotation angle between adjacent regions is desirably 20°, preferably 10°, and more preferably 5° or less. By arranging adjacent regions so as to minimize the angle difference, as many nanoantennas 22 as possible can be formed in each of the adjacent regions.

[0066] In the lighting device 100 of this embodiment, the nanoantenna 22 has a triangular lattice arrangement pattern in each of the first region A1, the second region A2, and the third region A3, but is not limited to this and may have, for example, a square lattice arrangement pattern.

[0067] When the nanoantennas 22 have a square lattice arrangement pattern in each region, the illumination pattern IP of the light emitted from the illumination device 100 irradiated onto the screen may have color unevenness due to a bright line pattern in which bright lines appear radially every 90°. A2 and angle θ A3 By making the angles different from each other and other than a multiple of 90°, it is possible to suppress color unevenness in the emitted light.

[0068] In the illumination device 100 of this embodiment, the nanoantenna 22 has a cylindrical shape, but is not limited thereto and may have other shapes. For example, the nanoantenna 22 may have a cone or a truncated cone shape. In this case, the diameter of the base of the nanoantenna having a cone or truncated cone shape corresponds to the diameter W of the nanoantenna 22 described above.

[0069] In the illumination device 100 of this embodiment, the wavelength conversion device 13 emits fluorescence upon receiving excitation light from the light emitting element 12 as a light source, but the light source is not limited to this, and for example, a laser light source that emits laser light may be used. In that case, the illumination device 100 may be configured such that the wavelength conversion device 13 and the light source are separated from each other.

[0070] [Method of manufacturing wavelength conversion device] A method for producing the wavelength converter 13 of the illumination device 100 in this embodiment will be described below with reference to FIGS.

[0071] First, a dielectric layer made of a transparent dielectric material such as TiO2 is formed by electron beam evaporation or sputtering over the upper surface of the flat phosphor portion 21. At this time, the thickness of the dielectric layer becomes the height H of the nanoantenna 22.

[0072] Next, a metal film made of aluminum (Al) is formed on the dielectric layer formed on the upper surface of the phosphor section 21, and a resist film made of resin is applied onto the metal film. After that, a nanoimprint mold having a plurality of holes is used to press the mold onto the resist film, and then the mold is peeled off, thereby performing a desired patterning on the resist film.

[0073] In this patterning, by matching the period and diameter of each of the multiple holes in the nanoimprint mold to the period P and diameter W of the nanoantenna 22 described above, a resist film can be formed in a shape that corresponds to the arrangement of the nanoantenna 22 in this embodiment.

[0074] At this time, by performing patterning while rotating the nanoimprint mold at a predetermined angle for each of the above-mentioned first region A1, second region A2, and third region A3, it is possible to form a resist film having a shape corresponding to the arrangement of the nanoantenna 22 in each of the first region A1, second region A2, and third region A3.

[0075] Next, using the patterned resist film as a mask, the metal film in the area where the nanoantenna 22 is not to be formed is dry-etched to form a metal mask for etching the dielectric layer.

[0076] Next, the dielectric layer on which the metal mask is formed is etched by dry etching. For example, when the metal film is made of Al and the transparent dielectric is made of TiO2, etching gases of chlorine (Cl) and argon (Ar) are used for the metal film, and etching gases of carbon tetrafluoride (CF4), Ar, and oxygen (O2) are used for the transparent dielectric.

[0077] Finally, the metal mask remaining in the above process is removed by dry etching or wet etching, thereby completing the production of the wavelength converter 13 including the nanoantenna 22 arranged as described above.

[0078] In addition, when the metal film is made of Al and the transparent dielectric is made of TiO2, the metal film is also partially etched when the dielectric layer is dry etched using an etching gas of CF4, Ar and O2. Therefore, if the thickness of the metal film on the dielectric layer is previously thin, the metal film and the dielectric layer are removed from the end of the dielectric layer during etching, and this method can form a nanoantenna having a conical or truncated conical shape.

[0079] [Modifications of lighting device] A modified example of the lighting device 100 according to the first embodiment will be described below with reference to Fig. 6. Fig. 6 is a top view of a lighting device 110 according to a modified example of the first embodiment. The lighting device 110 differs from the first embodiment in the arrangement of the nanoantennas 22, but is similar to the first embodiment in other respects, such as the period P, diameter W, and height H of the nanoantennas 22.

[0080] In the lighting device 110 of this modification, the nanoantennas 22 are arranged in a triangular lattice pattern in each of nine regions, the fourth region A4 to the twelfth region A12, which are arranged in a matrix. The arrangement patterns of the nanoantennas 22 in each of the fifth region A5 to the twelfth region A12 are rotated at different rotation angles around an axis perpendicular to the top surface of the phosphor section 21 with respect to the arrangement pattern in the fourth region A4.

[0081] The nanoantennas 22 in the fourth region A4 have an arrangement similar to that of the nanoantennas 22 in the first region A1 described above, and are arranged along the arrangement line AL4 to form a triangular lattice arrangement pattern.

[0082] The nanoantennas 22 in each of the fifth region A5 to the twelfth region A12 are arranged along the arrangement lines AL5 to AL12, respectively, to form a triangular lattice arrangement pattern. Each of the arrangement lines AL5 to AL12 forms an angle that is a multiple of 7° with a reference line (not shown in FIG. 6) that is parallel to the arrangement line AL4. The angle differs for each region and is an angle other than a multiple of 60°.

[0083] In other words, the arrangement pattern of the nanoantennas 22 in each of the fifth region A5 to the twelfth region A12 is a pattern obtained by rotating the arrangement pattern of the nanoantennas 22 in the fourth region A4 by an angle that is a multiple of 7° around an axis perpendicular to the top surface of the phosphor section 21.

[0084] Specifically, for example, the arrangement pattern of the nanoantennas 22 in the fifth region A5 is a pattern obtained by rotating the arrangement pattern of the nanoantennas 22 in the fourth region A4 by 7° around an axis perpendicular to the top surface of the phosphor section 21, and the arrangement pattern of the nanoantennas 22 in the sixth region A6 is a pattern obtained by rotating the arrangement pattern of the nanoantennas 22 in the fourth region A4 by 14° around an axis perpendicular to the top surface of the phosphor section 21.

[0085] That is, in a plan view of the lighting device 110 seen from above, the arrangement patterns of the nanoantennas 22 in adjacent regions among the fifth region A5 to the twelfth region A12 have a rotation angle of 7° with respect to each other.

[0086] Even in the case of the lighting device 110 of this modified example in which the arrangement pattern of the nanoantennas 22 is rotated in each of the areas arranged in a matrix, it is possible to suppress color unevenness in the light emitted from the lighting device 110 via the nanoantennas 22.

[0087] In the illumination device 110 of this modification, the arrangement patterns of the nanoantennas 22 in the fifth region A5 to the twelfth region A12 are rotated at different angles, but this does not need to be the case for all regions, and a plurality of regions may have the same angle. For example, there may be three regions each having an arrangement pattern rotated at angles of 7°, 28°, and 49°, respectively. EXAMPLES

[0088] [Lighting device of Example 2] Next, the configuration of an illumination device 200 according to Example 2 will be described with reference to Fig. 7 to Fig. 9. Fig. 7 is a cross-sectional view of the illumination device 200 taken along the same position as line 2-2 in Fig. 1. The illumination device 200 differs from Example 1 in that the wavelength conversion device 13 has a multilayer film reflector 23, but is otherwise similar to Example 1, for example, the arrangement of the nanoantennas 22 in the first area A1 to the third area A3.

[0089] The multilayer film reflector 23 is formed over the upper surface of the phosphor section 21, and is a reflector configured by laminating multiple layers of dielectric materials having relatively low refractive indexes and dielectric materials having high refractive indexes. On the upper surface of the multilayer film reflector 23, each of the nanoantennas 22 is formed in the manner shown in Example 1.

[0090] The multilayer film reflector 23 uses, for example, silicon oxide (SiO2) or Al2O3 as a low refractive index dielectric material, and TiO2, ZrO2, Nb2O5, La2O3, Ta2O5, or HfO2 as a high refractive index dielectric material.

[0091] In the lighting device 200, the multilayer film reflector 23 reflects light in the green wavelength range of light in the visible light region at a predetermined reflectance and transmits light of other wavelengths. That is, the multilayer film reflector 23 reflects only the fluorescent components in the green wavelength range of the fluorescent light generated in the phosphor section 21 and transmits fluorescent components other than the green wavelength range and blue light as excitation light that has transmitted through the phosphor section 21.

[0092] Fig. 8 is a graph showing an example of the reflectance of light with visible wavelengths in the multilayer film reflecting mirror 23. As shown in Fig. 8, the multilayer film reflecting mirror 23 has a reflectance of 60% or less for light in the green wavelength range of approximately 480 to 530 nm.

[0093] Therefore, in the lighting device 200 of the present embodiment, the multilayer film reflector 23 is formed over the upper surface of the phosphor section 21, so that when fluorescence in the green wavelength range, which may cause the color unevenness described above, reaches the multilayer film reflector 23, a portion of the fluorescence can be reflected into the phosphor section 21.

[0094] Fig. 9 is a graph showing the excitation spectrum of the phosphor in phosphor section 21 with respect to excitation light. In Fig. 9, the horizontal axis shows wavelength, and the vertical axis shows intensity. In Fig. 9, the region shown by the dashed dotted line shows light in the green wavelength range. As shown in Fig. 9, light in the green wavelength range has a lower intensity than blue light, but can excite the phosphor in phosphor section 21.

[0095] Therefore, in the lighting device 200 of this embodiment, by forming a multilayer film reflector 23 that reflects fluorescent components in the green wavelength range on the upper surface of the phosphor section 21, the fluorescent components reflected by the multilayer film reflector 23 can be used as excitation light that excites the phosphor of the phosphor section 21 again.

[0096] Therefore, according to the lighting device 200 of this embodiment, in addition to the effect of suppressing color unevenness of the emitted light by rotating the arrangement pattern of the nanoantennas 22 for each region, the multilayer film reflector 23 can also suppress color unevenness of the emitted light by preventing a part of the fluorescent component in the green wavelength range from being emitted from the phosphor section 21. Therefore, according to the lighting device 200 of this embodiment, it is possible to suppress color unevenness in the light emitted from the lighting device 200 via the nanoantennas 22.

[0097] The reflectance of the multilayer film reflector 23 for light in the green wavelength range is not limited to the above-mentioned reflectance and may be set appropriately. The reflectance may be set according to the number of regions for each array pattern of the nanoantenna 22, for example, and may be adjusted appropriately to the extent that the luminous flux of the light emitted from the lighting device 200 is not reduced. [Explanation of symbols]

[0098] 100, 110, 200 Lighting equipment 11 Mounting board 12 Light emitting element 13 Wavelength conversion device 15 Semiconductor structure layer 16 Support substrate 17p electrode 18n electrode 21 Phosphor section 22 Nano Antennas 23 Dielectric multilayer film

Claims

1. a flat phosphor portion including a phosphor that emits fluorescence when excited by excitation light; a plurality of nanoantennas made of a metal material or a dielectric material, the nanoantennas being arranged to form a lattice-like arrangement pattern in each of a plurality of regions on one surface of the phosphor section in a plan view seen from a direction perpendicular to the one surface; A wavelength conversion device characterized in that the arrangement pattern of the multiple nanoantennas in one of the multiple regions is a pattern obtained by rotating the arrangement pattern of the multiple nanoantennas in another region around an axis perpendicular to the one surface.

2. The nanoantennas are arranged to form a triangular lattice-shaped arrangement pattern in each of the regions, The wavelength conversion device according to claim 1, characterized in that the arrangement pattern of the plurality of nanoantennas in the one region is a pattern rotated at an angle other than a multiple of 60° relative to the arrangement pattern of the plurality of nanoantennas in the other region.

3. The nanoantennas are arranged to form a square lattice-like arrangement pattern in each of the regions, The wavelength conversion device according to claim 1, characterized in that the arrangement pattern of the plurality of nanoantennas in the one region is a pattern rotated at an angle other than a multiple of 90° relative to the arrangement pattern of the plurality of nanoantennas in the other region.

4. 2 . The wavelength conversion device according to claim 1 , wherein the plurality of regions are strip-shaped regions arranged along one direction in the plan view.

5. The wavelength conversion device according to claim 1 , wherein the plurality of regions are arranged in a matrix in the plan view.

6. 2. The wavelength conversion device according to claim 1, further comprising a dielectric multilayer film formed on said one surface of said phosphor portion and configured to reflect fluorescent components in a partial wavelength range within the wavelength range of said fluorescent light.

7. The fluorescence has a wavelength range of 480 to 700 nm, 7. The wavelength conversion device according to claim 6, wherein the dielectric multilayer film is configured to reflect fluorescent components in a wavelength range of 480 to 530 nm.

8. 8. The wavelength conversion device according to claim 7, wherein the dielectric multilayer film has a reflectance of 60% or less with respect to the fluorescent component.

9. The wavelength conversion device according to claim 1 , wherein the nanoantennas are arranged at a period of 420 nm or more and 520 nm or less in each of the regions.

10. The wavelength conversion device according to claim 9, characterized in that the multiple nanoantennas have a cylindrical, conical, or truncated conical shape in each of the multiple regions, and the diameter of the bottom surface is 75% or more and 85% or less of the period.

11. The wavelength conversion device according to claim 9 or 10, wherein the plurality of nanoantennas have a height of 225 nm or more and 325 nm or less in each of the plurality of regions.

12. A wavelength conversion device according to claim 1 , a light source that emits the excitation light toward another surface of the phosphor section opposite to the one surface; A lighting device comprising:

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