Phosphor element, wavelength conversion device, illumination device, and projector

Abstract

To provide a phosphor element, a wavelength conversion device, an illumination device, and a projector which achieve an improvement in fluorescence extraction efficiency.SOLUTION: A phosphor element includes an element body including a phosphor phase made of A3B5O12:Ce having a garnet structure, and a matrix phase having a refractive index higher than a refractive index of the phosphor phase. A content of the phosphor phase is 56 vol.% or more and 70 vol.% or less in a volume ratio with respect to the element body. A ratio of Ce to A in terms of the number of atoms is 0.004 or more and 0.04 or less. A thickness of the element body is 45 μm or more and 150 μm or less. A is at least one selected from the group consisting of Lu, Gd, Tb, Ga, and Y, and B is Al.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a phosphor element, a wavelength conversion device, an illumination device, and a projector. [Background technology]

[0002] Conventionally, ceramic composites have been used as wavelength conversion members for use in light sources for projectors. 2 O 3 , MgAl 2 O 4 This publication discloses a ceramic composite made of inorganic materials having a matrix phase made of a translucent ceramic such as MgO, and a phosphor phase made of YAG containing Ce. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-062459 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the ceramic composite disclosed in Patent Document 1, although the thermal conductivity is improved by mixing and sintering a highly thermally conductive filler, it is difficult to sufficiently improve the fluorescence extraction efficiency. [Means for solving the problem]

[0005] In order to solve the above problems, according to one aspect of the present invention, a garnet-structured A 3 B 5 O 12A phosphor element is provided, which is composed of an element body including a phosphor phase constituted by Lu, Gd, Tb, Ga and Y, and a matrix phase having a refractive index higher than that of the phosphor phase, the content of the phosphor phase being 56 vol% or more and 70 vol% or less in terms of volume ratio to the element body, the ratio of Ce to A in terms of the number of atoms being 0.004 or more and 0.04 or less, and the thickness of the element body being 45 μm or more and 150 μm or less, where A is at least one selected from the group consisting of Lu, Gd, Tb, Ga and Y, and B is Al.

[0006] According to another aspect of the present invention, there is provided a wavelength conversion device comprising: a substrate; a phosphor element of the above aspect that is provided on the substrate and converts incident excitation light into fluorescence; and a reflective layer that is provided on the opposite side to the light incident side of the phosphor element and reflects the excitation light and the fluorescence.

[0007] According to another aspect of the present invention, there is provided a wavelength conversion device comprising: a substrate; a phosphor element of the above aspect that is provided on the substrate and converts incident excitation light into fluorescence; and an optical layer that is provided on the light incident side of the phosphor element and transmits the excitation light and reflects the fluorescence.

[0008] According to another aspect of the present invention, there is provided an illumination device including a light source that emits excitation light, and the wavelength conversion device of the above aspect onto which the excitation light is incident.

[0009] According to another aspect of the present invention, there is provided a projector comprising an illumination device according to the above aspect, an optical modulator that modulates light emitted from the illumination device, and a projection optical device that projects the light modulated by the optical modulator. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic configuration diagram showing a projector according to a first embodiment. [Diagram 2] 1 is a schematic configuration diagram showing an illumination device according to a first embodiment. [Diagram 3]FIG. 1 is a cross-sectional view showing a configuration of a wavelength conversion device. [Figure 4] This is an SEM image of a phosphor element. [Diagram 5] FIG. 2 is a diagram showing an emission spectrum of a phosphor element. [Figure 6] FIG. 11 is a schematic configuration diagram showing an illumination device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the drawings used in the following description may show characteristic parts in an enlarged scale for the sake of convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component may not necessarily be the same as in reality.

[0012] (First embodiment) Hereinafter, one embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram showing a projector according to a first embodiment. 1, the projector 1 of this embodiment is a projection type image display device that displays an image on a screen SCR. The projector 1 includes an illumination device 2, a color separation optical system 3, a light modulation device 4R, a light modulation device 4G, a light modulation device 4B, a synthesis optical system 5, and a projection optical device 6.

[0013] The illumination device 2 emits white illumination light WL toward the color separation optical system 3. The configuration of the illumination device 2 will be described in detail later.

[0014] The color separation optical system 3 separates the illumination light WL emitted from the illumination device 2 into red light LR, green light LG, and blue light LB. The color separation optical system 3 includes a first dichroic mirror 7a, a second dichroic mirror 7b, a first total reflection mirror 8a, a second total reflection mirror 8b, a third total reflection mirror 8c, a first relay lens 9a, and a second relay lens 9b.

[0015] The first dichroic mirror 7a separates the illumination light WL from the illumination device 2 into red light LR and light containing green light LG and blue light LB. The first dichroic mirror 7a transmits the red light LR and reflects the light containing green light LG and blue light LB. On the other hand, the second dichroic mirror 7b reflects the green light LG and transmits the blue light LB. In this way, the second dichroic mirror 7b separates the light containing green light LG and blue light LB into green light LG and blue light LB.

[0016] The first total reflection mirror 8a is disposed in the optical path of the red light LR and reflects the red light LR transmitted through the first dichroic mirror 7a toward the optical modulation device 4R. On the other hand, the second total reflection mirror 8b and the third total reflection mirror 8c are disposed in the optical path of the blue light LB and guide the blue light LB transmitted through the second dichroic mirror 7b to the optical modulation device 4B. The green light LG is reflected from the second dichroic mirror 7b toward the optical modulation device 4G.

[0017] The first relay lens 9a is disposed between the second dichroic mirror 7b and the second total reflection mirror 8b in the optical path of the blue light LB. The second relay lens 9b is disposed between the second total reflection mirror 8b and the third total reflection mirror 8c in the optical path of the blue light LB. The first relay lens 9a and the second relay lens 9b compensate for the optical loss of the blue light LB caused by the optical path length of the blue light LB being longer than the optical path lengths of the red light LR and the green light LG.

[0018] The light modulation device 4R modulates the red light LR according to image information to form image light corresponding to the red light LR. The light modulation device 4G modulates the green light LG according to image information to form image light corresponding to the green light LG. The light modulation device 4B modulates the blue light LB according to image information to form image light corresponding to the blue light LB.

[0019] For example, a transmissive liquid crystal panel is used for each of the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B. Furthermore, a polarizing plate (not shown) is disposed on each of the incident side and the exit side of the liquid crystal panel.

[0020] A field lens 10R is disposed on the incident side of the optical modulation device 4R. The field lens 10R collimates the red light LR incident on the optical modulation device 4R. A field lens 10G is disposed on the incident side of the optical modulation device 4G. The field lens 10G collimates the green light LG incident on the optical modulation device 4G. A field lens 10B is disposed on the incident side of the optical modulation device 4B. The field lens 10B collimates the blue light LB incident on the optical modulation device 4B.

[0021] The image light emitted from the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B is incident on the combining optical system 5. The combining optical system 5 combines the image light corresponding to the red light LR, the green light LG, and the blue light LB, respectively, and emits the combined image light toward the projection optical device 6. The combining optical system 5 uses, for example, a cross dichroic prism.

[0022] The projection optical device 6 has a plurality of projection lenses. The projection optical device 6 enlarges and projects the image light combined by the combining optical system 5 onto the screen SCR. As a result, an enlarged image is displayed on the screen SCR.

[0023] The configuration of the lighting device 2 will be described below. FIG. 2 is a schematic diagram showing the configuration of an illumination device 2 according to the present embodiment. As shown in FIG. 2, the illumination device 2 includes a first light source 40, a collimating optical system 41, a dichroic mirror 42, a first focusing optical system 43, a wavelength conversion device 50, a second light source 44, a second focusing optical system 45, a diffusion plate 46, and a collimating optical system 47.

[0024] The first light source 40 is composed of a plurality of semiconductor lasers 40a that emit blue excitation light E made of laser light. The emission intensity of the excitation light E has a peak of, for example, 445 nm. The plurality of semiconductor lasers 40a are arranged in an array in a plane perpendicular to the optical axis ax of the first light source 40. Note that the semiconductor lasers 40a may be semiconductor lasers that emit blue light of a wavelength other than 445 nm, for example, 455 nm or 460 nm. The optical axis ax of the first light source 40 is perpendicular to the illumination optical axis 100ax of the illumination device 2. The first light source 40 of the present embodiment corresponds to the "light source" in the claims.

[0025] The collimating optical system 41 includes a first lens 41a and a second lens 41b. The collimating optical system 41 approximately collimates the light emitted from the first light source 40. Each of the first lens 41a and the second lens 41b is formed of a convex lens.

[0026] The dichroic mirror 42 is disposed in the optical path from the collimating optical system 41 to the first collecting optical system 43 in a direction intersecting at an angle of 45° with respect to both the optical axis ax of the first light source 40 and the illumination optical axis 100ax. The dichroic mirror 42 reflects the blue light component and transmits the red light component and the green light component. Thus, the dichroic mirror 42 reflects the excitation light E and the blue light B and transmits the yellow fluorescence Y.

[0027] The first focusing optical system 43 focuses the excitation light E transmitted through the dichroic mirror 42 and makes it incident on the wavelength conversion device 50, while approximately collimating the fluorescence Y emitted from the wavelength conversion device 50. The first focusing optical system 43 includes a first lens 43a and a second lens 43b. Each of the first lens 43a and the second lens 43b is formed by a convex lens.

[0028] The second light source 44 is composed of a semiconductor laser having the same wavelength band as the first light source 40. The second light source 44 may be composed of one semiconductor laser, or may be composed of multiple semiconductor lasers. The second light source 44 may also be composed of a semiconductor laser having a different wavelength band from the semiconductor laser of the first light source 40.

[0029] The second light collecting optical system 45 includes a first lens 45a and a second lens 45b. The second light collecting optical system 45 collects the blue light B emitted from the second light source 44 on or near the diffusion surface of the diffusion plate 46. Each of the first lens 45a and the second lens 45b is formed of a convex lens.

[0030] The diffusion plate 46 diffuses the blue light B emitted from the second light source 44, and generates blue light B having a light distribution close to the light distribution of the fluorescence Y emitted from the wavelength conversion device 50. As the diffusion plate 46, for example, ground glass made of optical glass can be used.

[0031] The collimating optical system 47 includes a first lens 47a and a second lens 47b. The collimating optical system 47 approximately collimates the light emitted from the diffusion plate 46. Each of the first lens 47a and the second lens 47b is formed of a convex lens.

[0032] The blue light B emitted from the second light source 44 is reflected by the dichroic mirror 42, emitted from the wavelength conversion device 50, and combined with the fluorescence Y transmitted through the dichroic mirror 42 to generate white illumination light WL. The illumination light WL is incident on the uniform illumination optical system 80.

[0033] The uniform illumination optical system 80 includes a first lens array 81, a second lens array 82, a polarization conversion element 83, and a superimposing lens 84.

[0034] The first lens array 81 has a plurality of first lenses 81a for splitting the illumination light WL from the illumination device 2 into a plurality of partial light beams. The plurality of first lenses 81a are arranged in a matrix in a plane perpendicular to the illumination optical axis 100ax.

[0035] The second lens array 82 has a plurality of second lenses 82a corresponding to the plurality of first lenses 81a of the first lens array 81. The plurality of second lenses 82a are arranged in a matrix in a plane perpendicular to the illumination optical axis 100ax.

[0036] The second lens array 82, together with the superimposing lens 84, forms images of the first lenses 81a of the first lens array 81 near the image forming areas of the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B, respectively.

[0037] The polarization conversion element 83 converts the light emitted from the second lens array 82 into one type of linearly polarized light. The polarization conversion element 83 includes, for example, a polarization separation film and a phase difference plate (not shown).

[0038] The superimposing lens 84 collects the partial light beams emitted from the polarization conversion element 83 and superimposes them near the image forming areas of the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B.

[0039] Next, the configuration of the wavelength converter 50 will be described. Fig. 3 is a cross-sectional view showing the configuration of the wavelength conversion device 50. Fig. 3 corresponds to a cross section of the wavelength conversion device 50 cut along a plane including the illumination optical axis 100ax in Fig. 2.

[0040] 3, the wavelength converter 50 includes a substrate 51, a phosphor element 52, a bonding layer 53, and a reflective layer 54. The wavelength converter 50 of the present embodiment is configured as a fixed-type wavelength converter in which the incident position of the excitation light E with respect to the phosphor element 52 does not change over time.

[0041] The substrate 51 supports the reflective layer 54 and the phosphor elements 52 via a bonding layer 53. The substrate 51 is made of a metal material having high thermal conductivity, such as aluminum or copper. The bonding layer 53 is made of a bonding material having high thermal conductivity, such as nano silver paste. The bonding layer 53 bonds a first surface 51a, which is the surface of the substrate 51, to the phosphor elements 52.

[0042] The phosphor element 52 has a first surface 52a facing the substrate 51 and a second surface 52b opposite to the first surface 52a. The phosphor element 52 emits fluorescence Y from the second surface 52b, which is wavelength-converted excitation light E incident from the second surface 52b. The phosphor element 52 is composed of an element body 52A including a phosphor phase 520 and a matrix phase 521.

[0043] The reflective layer 54 is provided facing the first surface 51a of the phosphor element 52 with the bonding layer 53 interposed therebetween. That is, the reflective layer 54 is provided between the substrate 51 and the first surface 52a of the phosphor element 52. The reflective layer 54 is made of a metal film such as silver having high light reflectance, a dielectric multilayer film, or a combination of these films. The reflective layer 54 reflects the fluorescence Y that has traveled toward the opposite side (first surface 52a side) to the light incident side in the phosphor element 52 toward the light incident side (second surface b side). The reflective layer 54 may reflect a part of the excitation light E toward the light incident side (second surface b side), and the excitation light E reflected by the reflective layer 54 is used to excite the fluorescence Y. The wavelength converter 50 of this embodiment functions as a reflection-type wavelength converter that emits fluorescence Y from the second surface 52b of the phosphor element 52 on which the excitation light E is incident.

[0044] Fig. 4 is a diagram showing a configuration of a main part of the phosphor element 52 of this embodiment. Fig. 4 is an image of the phosphor element 52 captured using a SEM (scanning electron microscope). The phosphor phase 520 shown in FIG. 3 B 5 O 12In the phosphor phase 520 of this embodiment, A is Y (yttrium) and B is AL (aluminum). That is, the phosphor phase 520 of this embodiment is made of yttrium aluminum garnet (YAG(YAG)) doped with cerium (Ce) as an activator. 3 Al 5 O 12 ):Ce) phosphor particles.

[0045] The matrix phase 521 is a translucent ceramic that functions as a binder to bind together the multiple phosphor particles that constitute the phosphor phase 520 and transmits the fluorescence emitted by the phosphor phase 520. The matrix phase 521 of this embodiment is made of AlN (aluminum nitride). The matrix phase 521 has a refractive index (2.2) higher than the refractive index (1.8) of YAG:Ce that constitutes the phosphor phase 520.

[0046] The thermal conductivity of AlN constituting the matrix phase 521 is approximately 285 W / m·K, and the thermal conductivity of YAG:Ce constituting the phosphor phase 520 is approximately 9 W / m·K. In other words, the matrix phase 521 has a thermal conductivity that is sufficiently higher than that of the phosphor phase 520.

[0047] The thermal conductivity of the matrix phase 521 of this embodiment is higher than that of Al, which is generally used as a matrix phase of a ceramic phosphor. 2 O 3 This is a value that is sufficiently higher than the thermal conductivity of aluminum oxide (approximately 30 W / m K). 2 O 3 Since the thermal conductivity is superior to that of conventional phosphor elements using a matrix phase, the phosphor element has excellent heat dissipation properties.

[0048] In the phosphor element 52 of this embodiment, the thickness of the element body 52A is set to 45 μm or more and 150 μm or less. Generally, phosphor elements are used with an optical layer, such as an anti-reflection layer, formed on the surface. For this reason, if the thickness of the element body 52A in the phosphor element 52 is less than 45 μm, forming an optical layer on the surface of the element body 52A may cause warping due to the deposition stress of the optical layer, resulting in damage. Furthermore, if the thickness is less than 45 μm, the thickness may be too thin and may cause cracks or the like during manufacturing. Furthermore, if the thickness exceeds 150 μm, the average transmittance of the fluorescence Y in the phosphor element 52 falls to less than 84%, thereby decreasing the efficiency of extracting the fluorescence Y. Note that an average transmittance of less than 84% for the fluorescence Y means that the fluorescence Y emitted from the phosphor element 52 is at a level that cannot be practically used as illumination light for a projector. Furthermore, if the thickness exceeds 150 μm, the thickness becomes too large, which may reduce the heat dissipation property of the phosphor element 52 and reduce the fluorescence conversion efficiency. In the present embodiment, the thickness of the phosphor element 52 is set to, for example, 45 μm.

[0049] It is generally known that when the temperature of a phosphor element increases, the fluorescence emission spectrum shifts to the long wavelength side and the luminous efficiency decreases. One of the reasons for this is that the energy used to convert the excitation light into fluorescence increases as the emission spectrum shifts to the long wavelength side. In other words, in order to increase the fluorescence conversion efficiency of a phosphor element, it is effective to reduce the shift of the emission spectrum to the long wavelength side that accompanies an increase in temperature.

[0050] The present inventors focused on increasing the fluorescence conversion efficiency of a phosphor element by suppressing the shift of the emission spectrum to the long wavelength side with increasing temperature. The present inventors then considered that a phosphor element in which the decrease in the fluorescence conversion efficiency due to temperature increase is suppressed can be realized by suppressing the shift of the emission spectrum to the long wavelength side with increasing temperature to 20 nm or less. The present inventors also considered that if the content of Ce in the phosphor phase is too small, the excitation light is not absorbed well in the phosphor phase, and the amount of extracted fluorescence is reduced.

[0051] Generally, if the content of Ce in the phosphor phase in a phosphor element is too high, the fluorescence generated in the phosphor phase is scattered toward the inside due to the refractive index difference with the matrix phase, and is reabsorbed by Ce, so that the fluorescence extraction yield may decrease. In particular, in the phosphor element 52 of this embodiment, the heat dissipation is improved by using AlN as the matrix phase 521 as described above, but AlN has a refractive index higher than that of alumina (1.63), which is generally used as a matrix phase. In other words, in the phosphor element 52 of this embodiment, the refractive index difference between the phosphor phase 520 and the matrix phase 521 is large, and Ce reabsorption may occur.

[0052] The inventors of the present invention considered that even if a phosphor element uses a matrix phase made of AlN, which has a higher refractive index than the phosphor phase, the Ce content in the phosphor phase and the thickness of the phosphor element can be appropriately set to suppress the decrease in the external quantum efficiency of the fluorescence and increase the amount of fluorescence extracted. The external quantum efficiency of the fluorescence Y means the ratio between the number of photons of the fluorescence Y emitted by excitation with the excitation light E and the number of photons of the excitation light E. More specifically, it is the value obtained by dividing the amount of the fluorescence Y emitted from the phosphor element 52 by the amount of the excitation light E irradiated on the phosphor element 52.

[0053] Specifically, the phosphor element 52 of this embodiment is YAG (Y 3 Al 5 O 12 ): The phosphor phase 520 is constituted by an element body 52A including a phosphor phase 520 constituted by Ce and a matrix phase 521 having a refractive index higher than that of the phosphor phase 520, the content of the phosphor phase 520 being 56 vol% or more and 70 vol% or less in terms of volume ratio in the element body 52A, and the content of Ce in the phosphor phase 520 being a ratio of the number of Ce atoms to Y being 0.004 or more and 0.04 or less. Hereinafter, in this specification, the volume ratio of the phosphor phase 520 to the element body 52A is referred to as the "YAG amount."

[0054] In the phosphor element 52 of this embodiment, when the amount of YAG is 56 vol% or more and 70 vol% or less, the ratio of the matrix phase 521 is determined to be within a predetermined range (33 vol% or more and 44 vol% or less). In the phosphor element 52 of this embodiment, the matrix phase 521 is made of AlN, which has high thermal conductivity. Therefore, the phosphor element 52 of this embodiment can efficiently release heat associated with fluorescent emission and suppress a decrease in fluorescence conversion efficiency associated with a rise in temperature. In other words, the phosphor element 52 of this embodiment has the matrix phase 521 with high thermal conductivity, which suppresses a rise in temperature and suppresses a shift in the emission spectrum of the fluorescent Y to the long wavelength side.

[0055] More specifically, the phosphor element 52 of this embodiment can have a thermal conductivity in the element body 52A of 20 (W / m K) or more, and therefore can efficiently dissipate heat associated with fluorescent emission, thereby effectively suppressing the decrease in fluorescence conversion efficiency associated with an increase in temperature.

[0056] In other words, in the phosphor element 52 of this embodiment, by setting the amount of YAG to be 56 vol% or more and 70 vol% or less, the fluorescence Y can be efficiently extracted by achieving a balance between improving the heat dissipation associated with fluorescent emission and suppressing re-absorption of the fluorescence Y due to the refractive index difference.

[0057] Fig. 5 is a diagram showing the emission spectrum of the phosphor element 52 of this embodiment. The horizontal axis of Fig. 5 indicates the wavelength of the fluorescence Y emitted by the phosphor element 52, and the vertical axis of Fig. 5 indicates the intensity of the emission spectrum. Furthermore, the solid line in Fig. 5 indicates the emission spectrum of the phosphor element 52 at room temperature (25°C), and the dashed line in Fig. 5 indicates the emission spectrum of the phosphor element 52 at a high temperature (250°C). Note that the high temperature of 250°C is the maximum temperature assumed for the phosphor element 52 when used as an illumination device for a projector.

[0058] As shown in FIG. 5, in the phosphor element 52 of the present embodiment, the emission peak wavelength P1 of the spectrum at room temperature is 533 nm, and the emission peak wavelength P2 of the spectrum at high temperature is 548 nm. That is, in the case of the phosphor element 52 of the present embodiment, the shift amount of the emission spectrum generated at high temperature (250 ° C) is 17 nm. That is, according to the phosphor element 52 of the present embodiment, the shift amount of the emission spectrum at high temperature can be suppressed to 20 nm or less.

[0059] As described above, the phosphor element 52 of the present embodiment can suppress the shift amount of the emission spectrum accompanying the temperature rise to 20 nm or less by increasing the heat dissipation property by setting the YAG amount to 56 vol% or more and 70 vol% or less. As a result, the fluorescence conversion efficiency can be increased by suppressing the energy used during fluorescence conversion due to the spectrum shift, thereby generating bright fluorescence Y.

[0060] Further, according to the phosphor element 52 of the present embodiment, by setting the content of Ce in the phosphor phase 520 to 0.004 or more and 0.04 or less, the excitation light E incident from the second surface 52b is appropriately absorbed by the phosphor phase 520, thereby suppressing the backscattering of the excitation light E and increasing the fluorescence conversion efficiency and increasing the extraction amount of the fluorescence Y. Therefore, the external quantum efficiency of the fluorescence Y due to the excitation light E incident from the second surface 52b can be 55% or more. Note that the external quantum efficiency of 55% or more means that the fluorescence Y emitted from the phosphor element 52 has no problem in actual use as the illumination light for the projector. Further, since the phosphor element 52 of the present embodiment has a matrix phase 521 made of AlN having a high thermal conductivity, it is possible to suppress a decrease in the fluorescence conversion efficiency accompanying the temperature rise by efficiently releasing the heat accompanying the fluorescence emission. Therefore, the phosphor element 52 of the present embodiment can efficiently generate bright fluorescence Y.

[0061] Furthermore, in the phosphor element 52 of this embodiment, by setting the thickness of the element body 52A to be 45 μm or more and 150 μm or less, the average transmittance of the fluorescence Y can be set to be 84% or more and 97% or less. Therefore, the phosphor element 52 can efficiently extract the fluorescence Y generated inside to the outside by transmitting it.

[0062] The wavelength conversion device 50 of this embodiment comprises a substrate 51, a phosphor element 52 provided on the substrate 51 for converting incident excitation light E into fluorescence, and a reflective layer 54 provided on the side opposite the light incident side of the phosphor element 52. According to the wavelength converter 50 of the present embodiment, a reflective wavelength converter that efficiently extracts bright fluorescence Y can be provided.

[0063] The illumination device 2 of this embodiment includes a first light source 40 that emits excitation light E, and a wavelength conversion device 50 into which the excitation light E is incident. According to the lighting device 2 of the present embodiment, it is possible to provide a lighting device that has excellent wavelength conversion efficiency and emits bright illumination light WL.

[0064] The projector 1 of this embodiment includes an illumination device 2, light modulation devices 4R, 4G, and 4B that modulate the light emitted from the illumination device 2, and a projection optical device 6 that projects the light modulated by the light modulation devices 4R, 4G, and 4B.

[0065] According to the projector 1 of the present embodiment, it is possible to provide a highly efficient projector with excellent display quality.

[0066] Second embodiment The projector according to the second embodiment will be described below. The basic configuration of the projector of the second embodiment is similar to that of the first embodiment, but the configuration of the illumination device is different from that of the first embodiment, so the configuration of the illumination device will be described below.

[0067] FIG. 6 is a schematic configuration diagram showing an illumination device 2A according to the second embodiment. In FIG. 6, components common to those in the drawings used in the above embodiment are given the same reference numerals, and description thereof will be omitted.

[0068] As shown in FIG. 6, the illumination device 2A includes an excitation light source unit 10, an afocal optical system 11, a homogenizer optical system 12, a focusing optical system 13, a wavelength conversion device 250, a pickup optical system 30, and a uniform illumination optical system 80.

[0069] The excitation light source unit 10 is composed of a plurality of semiconductor lasers 10a that emit blue excitation light E composed of laser light, and a plurality of collimator lenses 10b. The plurality of semiconductor lasers 10a are arranged in an array in a plane perpendicular to the illumination optical axis 100ax. The collimator lenses 10b are arranged in an array in a plane perpendicular to the illumination optical axis 100ax so as to correspond to each semiconductor laser 10a. The collimator lenses 10b convert the excitation light E emitted from the semiconductor lasers 10a corresponding to the collimator lenses 10b into parallel light. The excitation light source unit 10 of this embodiment corresponds to the "light source" in the claims.

[0070] The afocal optical system 11 includes, for example, a convex lens 11a and a concave lens 11b. The afocal optical system 11 reduces the beam diameter of the excitation light E emitted from the excitation light source unit 10 and consisting of a parallel beam.

[0071] The homogenizer optical system 12 includes, for example, a first multi-lens array 12a and a second multi-lens array 12b. The homogenizer optical system 12 makes the light intensity distribution of the excitation light uniform on the phosphor element 52 of the wavelength conversion device 250, that is, a so-called top hat distribution. The homogenizer optical system 12, together with the focusing optical system 13, superimposes a plurality of small light beams emitted from a plurality of lenses of the first multi-lens array 12a and the second multi-lens array 12b on the phosphor element 52 of the wavelength conversion device 250. This makes the light intensity distribution of the excitation light E irradiated on the phosphor element 52 uniform.

[0072] The focusing optical system 13 includes, for example, a first lens 13a and a second lens 13b. In this embodiment, the first lens 13a and the second lens 13b are each formed of a convex lens. The focusing optical system 13 is disposed in the optical path from the homogenizer optical system 12 to the wavelength conversion device 250, and focuses the excitation light E to make it incident on the phosphor element 52 of the wavelength conversion device 250.

[0073] The wavelength converter 250 of this embodiment includes a substrate 251, a phosphor element 52, a bonding layer 253, and an optical layer 254. The wavelength converter 250 of this embodiment is configured as a fixed type wavelength converter in which the incident position of the excitation light E with respect to the phosphor element 52 does not change over time.

[0074] The substrate 251 supports the optical layer 254 and the phosphor elements 52 via a bonding layer 253. The substrate 251 is made of a light-transmitting material such as glass or plastic. The bonding layer 253 in this embodiment is made of a light-transmitting material such as epoxy. The bonding layer 253 bonds a first surface 251a, which is the surface of the substrate 251, to the phosphor elements 52.

[0075] In the phosphor element 52 of this embodiment, excitation light E is incident on a first surface 52a facing the substrate 251, and fluorescence Y is emitted from a second surface 52b. In the wavelength conversion device 250 of this embodiment, the phosphor element 52 transmits and emits a portion of excitation light E1 that has not been wavelength-converted, in addition to the fluorescence Y. This causes white illumination light WL1 to be emitted from the phosphor element 52.

[0076] The optical layer 254 is provided on a first surface 52a which is the light incident side of the phosphor element 52. The optical layer 254 is composed of a dichroic mirror which transmits the excitation light E and reflects the fluorescence Y.

[0077] The wavelength converter 250 of this embodiment functions as a transmissive wavelength converter that emits illumination light WL1 containing fluorescence Y from a second surface 52b opposite to a first surface 52a of the phosphor element 52 onto which excitation light E is incident.

[0078] The pickup optical system 30 includes, for example, a first collimating lens 31 and a second collimating lens 32. The pickup optical system 30 is a collimating optical system that approximately collimates the light emitted from the phosphor element 52 of the wavelength conversion device 250. The first collimating lens 31 and the second collimating lens 32 are each composed of a convex lens. The light collimated by the pickup optical system 30 enters the uniform illumination optical system 80.

[0079] (Effects of the second embodiment) According to this embodiment, by using the phosphor element 52 capable of increasing the amount of extracted fluorescence Y, it is possible to realize a transmissive wavelength conversion device 250 that generates bright fluorescence Y. Also, by providing the illumination device 2A of this embodiment with the transmissive wavelength conversion device 250, it is possible to obtain the same effect as in the first embodiment, that is, excellent wavelength conversion efficiency and the ability to emit bright illumination light WL1.

[0080] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. The specific descriptions of the shape, number, arrangement, material, manufacturing method, etc. of each component of the phosphor element, wavelength conversion device, lighting device, and projector shown in the above embodiments are not limited to the above embodiments and can be modified as appropriate.

[0081] In the above embodiment, YAG containing Ce is used as the phosphor phase 520. 3 Al 5 O 12 , Tb 3 Al 5 O 12 , Ga 3 Al 5 O 12 , Gd 3 Al 5 O 12 The present invention is also applicable to the case where a phosphor phase containing Ce in at least one of the garnet structure (A 3 B 5 O12 In addition to Y (yttrium), A in Ce) can also be replaced with Lu (lutetium), Gd (gadolinium), Tb (terbium), or Ga (gallium), which has the same luminescence characteristics as Y, and therefore the present invention is also applicable when A is replaced with any of these.

[0082] The following is a summary of this disclosure. (Appendix 1) A with garnet structure 3 B 5 O 12 A phosphor phase composed of Ce; a matrix phase having a refractive index higher than that of the phosphor phase; The content of the phosphor phase is 56 vol% or more and 70 vol% or less in terms of a volume ratio with respect to the element body, The ratio of the number of Ce atoms to A is 0.004 or more and 0.04 or less, The thickness of the element body is 45 μm or more and 150 μm or less. A phosphor element characterized by: Here, A is at least one selected from the group consisting of Lu, Gd, Tb, Ga and Y, and B is Al.

[0083] According to the phosphor element of this configuration, it is possible to suppress the reabsorption of the fluorescence in the phosphor phase to increase the external quantum efficiency, and to increase the amount of extracted fluorescence by balancing the thermal conductivity and the external quantum efficiency. In addition, by appropriately adjusting the thickness of the phosphor element, it is possible to increase the average transmittance of the fluorescence, thereby further increasing the efficiency of extracting the fluorescence. Therefore, the phosphor element of this configuration can efficiently generate bright fluorescence.

[0084] (Appendix 2) A is Y, 2. A phosphor element according to claim 1.

[0085] According to this configuration, YAG(Y 3 Al 5 O 12): A phosphor element that efficiently generates bright fluorescence containing a phosphor phase composed of Ce can be realized.

[0086] (Appendix 3) The matrix phase is AlN. 3. The phosphor element according to claim 1 or 2,

[0087] According to this configuration, since the matrix phase is made of AlN, which has high thermal conductivity, the heat generated by the fluorescent light emission can be efficiently released, thereby suppressing the decrease in the fluorescent light conversion efficiency caused by the temperature rise.

[0088] (Appendix 4) The average transmittance of light having a wavelength band of 500 nm or more and 800 nm or less is 84% ​​or more and 97% or less. 4. The phosphor element according to claim 1, wherein the phosphor element is a fluorine-containing compound.

[0089] According to this configuration, it is possible to realize a configuration that efficiently extracts fluorescence having a wavelength band of 500 nm or more and 800 nm or less.

[0090] (Appendix 5) A substrate; A phosphor element according to any one of claims 1 to 4, which is provided on the substrate and converts incident excitation light into fluorescent light; A reflective layer is provided on the opposite side to the light incident side of the phosphor element. A wavelength conversion device characterized by:

[0091] According to the wavelength converter having this configuration, it is possible to provide a reflective wavelength converter that efficiently extracts bright fluorescent light.

[0092] (Appendix 6) A substrate; A phosphor element according to any one of claims 1 to 4, which is provided on the substrate and converts incident excitation light into fluorescent light; an optical layer provided on the light incident side of the phosphor element, the optical layer transmitting the excitation light and reflecting the fluorescence; A wavelength conversion device characterized by the following.

[0093] According to the wavelength conversion device of this configuration, a transmissive wavelength conversion device that efficiently extracts bright fluorescence can be provided.

[0094] (Appendix 7) A light source that emits the excitation light, The wavelength conversion device according to Appendix 5 or Appendix 6, into which the excitation light is incident, and comprising: An illumination device characterized by the following.

[0095] According to the illumination device of this configuration, an illumination device with excellent wavelength conversion efficiency and that emits bright illumination light can be provided.

[0096] (Appendix 8) The illumination device according to Appendix 7, An optical modulation device that modulates the light emitted from the illumination device, A projection optical device that projects the light modulated by the optical modulation device, and comprising: A projector characterized by the following.

[0097] According to the projector of this configuration, a projector with excellent display quality and high efficiency can be provided.

Example

[0098] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0099] (First Evaluation) Generally, the higher the number of Ce atoms with respect to the number of Y atoms in YAG (Y 3 Al 5 O 12 ):Ce (hereinafter referred to as the Ce / Y ratio), the higher the external quantum efficiency. First, the Ce / Y ratio was fixed at a low value of 0.004, and the following Examples 1-3 and Comparative Examples 1 and 2 were created as samples with different phosphor phase contents, and each sample was evaluated.

[0100] Example 1 First, the AlN powder that becomes the matrix phase is mixed with YAG powder with a Ce / Y ratio of 0.004 and a phosphor phase content of 56 vol% in the volume ratio of the entire phase including the matrix phase and the phosphor phase, and then uniaxially molded to a size of Φ20 mm and fired at 1800° C. in a nitrogen atmosphere. After that, the phosphor element of Example 1 with a thickness of 45 μm was produced by polishing.

[0101] Example 2 A phosphor element of Example 2 was manufactured by carrying out the same steps as in Example 1, except that a powder having a phosphor phase content of 60 vol % was used as the YAG powder.

[0102] Example 3 A phosphor element of Example 3 was manufactured by carrying out the same steps as in Example 1, except that a powder having a phosphor phase content of 70 vol % was used as the YAG powder.

[0103] Comparative Example 1 A phosphor element of Comparative Example 1 was manufactured by carrying out the same steps as in Example 1, except that a powder having a phosphor phase content of 50 vol % was used as the YAG powder.

[0104] Comparative Example 2 A phosphor element of Comparative Example 2 was manufactured by carrying out the same steps as in Example 1, except that a powder having a phosphor phase content of 80 vol % was used as the YAG powder.

[0105] (Evaluation of Examples 1-3 and Comparative Examples 1 and 2) The external quantum efficiency (unit: %) and thermal conductivity (unit: W / m K) were confirmed for the above-mentioned Examples 1-3 and Comparative Examples 1 and 2, and phosphor elements with high external quantum efficiency and thermal conductivity were determined to be phosphors with high light utilization efficiency and excellent heat dissipation. The results are shown in Table 1.

[0106] In Table 1, samples with an external quantum efficiency of 55% or more were rated A (passable), and samples with an external quantum efficiency of less than 55% were rated B (unacceptable). Also, in Table 1, samples with a thermal conductivity of 20% or more were rated A (passable), and samples with a thermal conductivity of less than 20% were rated B (unacceptable). In the overall evaluation, samples that achieved an A in both the evaluation items of external quantum efficiency and thermal conductivity were rated as A (passable), and samples that achieved a B in either the evaluation item of external quantum efficiency or thermal conductivity were rated as B (unacceptable).

[0107] [Table 1]

[0108] As shown in Table 1, in the case of Comparative Example 1 (YAG content 50%), the increase in the proportion of the matrix phase allows a sufficient thermal conductivity of 41.4 to be obtained, but the decrease in the proportion of the phosphor phase prevents the excitation light from being absorbed by the phosphor phase, and the external quantum efficiency drops to 53%. Also, in the case of Comparative Example 2 (YAG content 80%), the external quantum efficiency is sufficient at 62%, but the thermal conductivity is insufficient at 14.

[0109] From the above results, it was confirmed that, with the phosphor element of Example 1-3, by setting the YAG amount to 56% or more and 70% or less, the thermal conductivity and quantum yield can be increased in a balanced manner, thereby increasing the efficiency of fluorescence extraction and generating bright fluorescence.

[0110] (Second evaluation) Next, an appropriate range of Ce / Y ratio was evaluated. The content of the phosphor phase with the lowest external quantum efficiency of fluorescence within the range of the YAG amount in Table 1 was fixed at 56 vol%, and samples with different Ce / Y ratios were prepared as the following Examples 4-11 and Comparative Examples 3 and 4, and each sample was evaluated.

[0111] Example 4 A phosphor element of Example 4 was manufactured by carrying out the same steps as in Example 1, except that a powder having a Ce / Y ratio of 0.007 was used as the YAG powder.

[0112] Example 5 A phosphor element of Example 5 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.01 was used as the YAG powder.

[0113] Example 6 A phosphor element of Example 6 was manufactured by carrying out the same steps as in Example 1, except that a powder having a Ce / Y ratio of 0.013 was used as the YAG powder.

[0114] Example 7 A phosphor element of Example 7 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.015 was used as the YAG powder.

[0115] Example 8 A phosphor element of Example 8 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.02 was used as the YAG powder.

[0116] Example 9 A phosphor element of Example 9 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.025 was used as the YAG powder.

[0117] Example 10 A phosphor element of Example 10 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.03 was used as the YAG powder.

[0118] Example 11 A phosphor element of Example 11 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.04 was used as the YAG powder.

[0119] Comparative Example 3 A phosphor element of Comparative Example 3 was manufactured by carrying out the same steps as in Example 1, except that a powder having a Ce / Y ratio of 0.002 was used as the YAG powder.

[0120] Comparative Example 4 A phosphor element of Comparative Example 4 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.05 was used as the YAG powder.

[0121] (Evaluation of Examples 4-11 and Comparative Examples 3 and 4) The external quantum efficiency (unit: %) was confirmed for the above-mentioned Examples 4-11 and Comparative Examples 3 and 4, and phosphor elements with high external quantum efficiency were determined to have phosphors with high light utilization efficiency. The results are shown in Table 2.

[0122] In Table 2, samples with an external quantum efficiency of 55% or more were evaluated as A (passable), and samples with an external quantum efficiency of less than 55% were evaluated as B (unacceptable).

[0123] [Table 2]

[0124] As shown in Table 2, in the case of Comparative Example 3 (Ce / Y ratio 0.002), the Ce / Y ratio was too low, so that the excitation light was not absorbed by the phosphor phase, the proportion of backscattered light increased, and the external quantum efficiency of the fluorescence decreased to 54%. In other words, it was confirmed that Ce / Y needs to be 0.0004 or more, as in the phosphor element of Example 1. In addition, it was confirmed that the external quantum efficiency of fluorescence increases with increasing Ce / Y ratio in the phosphor elements of Examples 4-10. It was also confirmed that the external quantum efficiency is highest at Ce / Y ratios of around 0.02 and 0.025 (Examples 8 and 9), begins to decrease at Ce / Y ratios of 0.03 (Example 10) and 0.04 (Example 11), and significantly decreases to 40% at a Ce / Y ratio of 0.05 (Comparative Example 4). This is because the amount of Ce in the phosphor phase of the phosphor element was too high, which increased the reabsorption of fluorescence by Ce. In other words, it was confirmed that by setting the Ce / Y ratio to 0.004 or less as in the phosphor element of Example 11, the reabsorption of fluorescence was suppressed and a sufficient external quantum efficiency could be achieved.

[0125] (Third Evaluation) The external quantum efficiency of a phosphor element varies depending on its thickness. This is because the transmittance of light having a wavelength band of 500 nm to 800 nm varies depending on the thickness. In response to this, the content of the phosphor phase with the lowest external quantum efficiency was fixed at 56 vol%, and samples were created in which the Ce / Y ratio and the thickness of the element body were changed as in the following Examples 12-25 and Comparative Examples 5-9, and each sample was evaluated.

[0126] Example 12 A phosphor element of Example 12 was manufactured by carrying out the same steps as in Example 1, except that the thickness of the element body was set to 100 μm.

[0127] (Example 13) A phosphor element of Example 13 was manufactured by carrying out the same steps as in Example 1, except that the thickness of the element body was set to 150 μm.

[0128] Comparative Example 5 A phosphor element of Comparative Example 5 was produced by carrying out the same steps as in Example 1, except that the thickness of the element body was set to 200 μm.

[0129] Example 14 A phosphor element of Example 14 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.01 was used as the YAG powder.

[0130] Example 15 A phosphor element of Example 15 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.01 was used as the YAG powder and the thickness of the element body was 100 μm.

[0131] (Example 16) A phosphor element of Example 16 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.01 was used as the YAG powder and the thickness of the element body was 150 μm.

[0132] Comparative Example 6 A phosphor element of Comparative Example 6 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.01 was used as the YAG powder and the thickness of the element body was 200 μm.

[0133] (Example 17) A phosphor element of Example 17 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.015 was used as the YAG powder.

[0134] (Example 18) A phosphor element of Example 18 was manufactured by carrying out the same steps as in Example 1, except that the YAG powder used had a Ce / Y ratio of 0.015 and the thickness of the element body was 100 μm.

[0135] (Example 19) A phosphor element of Example 19 was manufactured by carrying out the same steps as in Example 1, except that the YAG powder used had a Ce / Y ratio of 0.015 and the thickness of the element body was 150 μm.

[0136] Comparative Example 7 A phosphor element of Comparative Example 7 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.015 was used as the YAG powder and the thickness of the element body was 200 μm.

[0137] (Example 20) A phosphor element of Example 20 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.025 was used as the YAG powder.

[0138] Example 21 A phosphor element of Example 21 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.025 was used as the YAG powder and the thickness of the element body was 100 μm.

[0139] Example 22 A phosphor element of Example 22 was manufactured by carrying out the same steps as in Example 1, except that the YAG powder used had a Ce / Y ratio of 0.025 and the thickness of the element body was 150 μm.

[0140] Comparative Example 8 A phosphor element of Comparative Example 8 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.025 was used as the YAG powder and the thickness of the element body was 200 μm.

[0141] Example 23 A phosphor element of Example 23 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.04 was used as the YAG powder.

[0142] (Example 24) A phosphor element of Example 24 was manufactured by carrying out the same steps as in Example 1, except that the YAG powder used had a Ce / Y ratio of 0.04 and the thickness of the element body was 100 μm.

[0143] (Example 25) A phosphor element of Example 25 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.04 was used as the YAG powder and the thickness of the element body was 150 μm.

[0144] Comparative Example 9 A phosphor element of Comparative Example 9 was manufactured by carrying out the same steps as in Example 1, except that a powder with a Ce / Y ratio of 0.04 was used as the YAG powder and the thickness of the element body was 200 μm.

[0145] (Evaluation of Examples 12-25 and Comparative Examples 5-9) For the above-mentioned Examples 12-25 and Comparative Examples 5-9, the external quantum efficiency (unit: %) and average transmittance (unit: %) were confirmed, and phosphor elements with high external quantum efficiency and average transmittance were determined to have high light utilization efficiency. The results are shown in Table 3.

[0146] In Table 3, samples with an external quantum efficiency of 55% or more were rated A (passable), and samples with an external quantum efficiency of less than 55% were rated B (unacceptable). Also, in Table 3, samples with an average transmittance of 84% or more were rated A (passable), and samples with an average transmittance of less than 84% were rated B (unacceptable). In addition, as an overall evaluation, samples that achieved an A in both the evaluation items of external quantum efficiency and average transmittance were rated as A (passable), and samples that achieved a B in either the evaluation item of external quantum efficiency or average transmittance were rated as B (unacceptable).

[0147] [Table 3]

[0148] As shown in Table 3, when phosphor elements with the same Ce / Y ratio are compared, it can be confirmed that the thinner the phosphor element, the higher the external quantum efficiency and average transmittance. On the other hand, in each of Comparative Examples 5-9 (thickness 200 μm), it was confirmed that at least one of the external quantum efficiency and average transmittance was an insufficient value. In other words, it was confirmed from Table 3 that if the thickness of the phosphor element is set to 45 μm or more and 150 μm or less, the external quantum efficiency and average transmittance can be increased in a balanced manner, thereby increasing the fluorescence extraction efficiency.

[0149] From the above results, it was confirmed that, according to the phosphor elements of Examples 1 to 25, by setting the YAG amount to 56% or more and 70% or less, the Ce / Y ratio to 0.004 or more and 0.04 or less, and the thickness of the element body to 45 μm or more and 150 μm or less, the external quantum efficiency and the average light transmittance are increased in a balanced manner, thereby increasing the fluorescence extraction efficiency and generating bright fluorescence. [Explanation of symbols]

[0150] 1...projector, 2, 2A...illumination device, 4B, 4G, 4R...light modulation device, 6...projection optical device, 50, 250...wavelength conversion device, 51, 251...substrate, 52...phosphor element, 52A...element body, 54...reflective layer, 254...optical layer, 520...phosphor phase, 521...matrix phase, E, E1...excitation light, Y...fluorescence.

Claims

1. A having a garnet structure ３ B ５ O １２ A phosphor phase composed of Ce; a matrix phase having a refractive index higher than that of the phosphor phase; The content of the phosphor phase is 56 vol% or more and 70 vol% or less in terms of a volume ratio with respect to the element body, The ratio of the number of Ce atoms to A is 0.004 or more and 0.04 or less, The thickness of the element body is 45 μm or more and 150 μm or less. A phosphor element characterized by: Here, A is at least one selected from the group consisting of Lu, Gd, Tb, Ga and Y, and B is Al.

2. A is Y, 2. The phosphor element according to claim 1 .

3. The matrix phase is AlN.

3. The phosphor element according to claim 1 or 2.

4. The average transmittance of light having a wavelength band of 500 nm or more and 800 nm or less is 84% ​​or more and 97% or less.

3. The phosphor element according to claim 1 or 2.

5. A substrate; The phosphor element according to claim 1 , which is provided on the substrate and converts incident excitation light into fluorescent light; A reflective layer is provided on the opposite side to the light incident side of the phosphor element. A wavelength conversion device characterized by:

6. A substrate; The phosphor element according to claim 1 , which is provided on the substrate and converts incident excitation light into fluorescent light; an optical layer provided on the light incident side of the phosphor element, the optical layer transmitting the excitation light and reflecting the fluorescence; A wavelength conversion device characterized by:

7. A light source that emits the excitation light; The wavelength conversion device according to claim 5 or 6, into which the excitation light is incident. A lighting device characterized by:

8. A lighting device according to claim 7; a light modulation device that modulates the light emitted from the illumination device; a projection optical device that projects the light modulated by the light modulation device. A projector characterized by:

Images