Wavelength conversion element, lighting device and projector

Abstract

To provide a wavelength conversion element, a lighting unit, and a projector having high efficiency for light utilization.SOLUTION: A wavelength conversion element of the present invention comprises: a substrate; a reflection layer that is provided on the substrate; a wavelength conversion layer that is provided on the reflection layer and converts light in a first wavelength range into light in a second wavelength range different from the first wavelength range; a structure that is provided on the wavelength conversion layer and scatters part of the light in the first wavelength range; and an optical layer that is provided on the structure, reflects part of the light in the first wavelength range, transmits the other part of the light in the first wavelength range, and transmits the light in the second wavelength range. The structure includes a first structure part, a second structure part, and a flat part that is provided between the first structure part and the second structure part. The optical layers provided in the first structure part and the second structure part have a first reflectance to the light in the first wavelength range. The optical layer provided in the flat part has a second reflectance different from the first reflectance to the light in the first wavelength range.SELECTED DRAWING: Figure 6B

Description

[Technical field]

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

[0002] Conventionally, there has been an illumination device that scatters and reflects a portion of light of a first wavelength using a light diffusion surface provided on the surface of a wavelength conversion layer, and emits white illumination light by combining fluorescence of a second wavelength obtained by wavelength-converting the light of the first wavelength that entered the wavelength conversion layer with the scattered and reflected light of the first wavelength (see, for example, Patent Documents 1 and 2 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-215549 A [Patent Document 2] JP 2017-194523 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned lighting device, the scattering angle of the light of the first wavelength is insufficient and there is room for improvement in the control of the scattering characteristics, so that the light of the first wavelength cannot be efficiently extracted as illumination light, resulting in a problem of reduced light utilization efficiency. [Means for solving the problem]

[0005] In order to solve the above problem, according to a first aspect of the present invention, there is provided a wavelength conversion element comprising: a substrate; a reflective layer provided on the substrate; a wavelength conversion layer provided on the reflective layer and converting light of a first wavelength band to light of a second wavelength band different from the first wavelength band; a structure provided on the wavelength conversion layer and scattering a portion of the light of the first wavelength band; and an optical layer provided on the structure and reflecting a portion of the light of the first wavelength band, transmitting another portion of the light of the first wavelength band, and transmitting light of the second wavelength band, wherein the structure includes a first structure, a second structure, and a flat portion provided between the first structure and the second structure, wherein the optical layer provided on the first structure and the second structure has a first reflectance for light of the first wavelength band, and the optical layer provided on the flat portion has a second reflectance for light of the first wavelength band different from the first reflectance.

[0006] According to a second aspect of the present invention, there is provided an illumination device comprising: a wavelength conversion element according to the first aspect; a light source that emits light of the first wavelength band; and a reflecting member that reflects the light of the first wavelength band emitted from the light source toward the wavelength conversion element.

[0007] According to a third aspect of the present invention, there is provided a projector comprising: an illumination device according to the second aspect of the present invention; an optical modulator that modulates light from the illumination device in accordance with image information; and a projection optical device that projects the light modulated by the optical modulator. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a projector according to an embodiment. [Diagram 2] FIG. 1 is a diagram showing a schematic configuration of a lighting device. [Diagram 3] FIG. 2 is a cross-sectional view showing a configuration of a wavelength conversion element. [Figure 4A] FIG. 4 is a diagram showing the surface reflectance spectrum of the second layer covering the flat portion. [Figure 4B] FIG. 4 is a diagram showing the angular characteristics of reflectance of a first light in a second layer. [Figure 5A] FIG. 4 is a diagram showing the surface reflectance spectrum of a first layer covering a structure. [Figure 5B] FIG. 4 is a diagram showing the reflectance angle characteristics of a first light in a first layer. [Figure 6A] 4 is an enlarged plan view of a main portion illustrating a first light reflected by a wavelength conversion element. FIG. [Figure 6B] 6B is an enlarged cross-sectional view of a main part taken along line BB in FIG. 6A. [Figure 7] 11 is a diagram showing the light distribution characteristics of scattered reflected light by a wavelength conversion element. FIG. [Figure 8] FIG. 13 is a diagram showing a configuration in which a structure and a wavelength conversion layer are integrally formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The projector of this embodiment is an example of a projector that uses a liquid crystal panel as a light modulation device. In the drawings, the dimensions of the components may be shown on different scales in order to make the components easier to see.

[0010] FIG. 1 is a diagram showing the configuration of a projector according to the present embodiment. The projector 1 of this embodiment shown in Fig. 1 is a projection type image display device that displays a color image on a screen (projection surface) SCR. The projector 1 uses three light modulation devices corresponding to the respective colors of red light LR, green light LG, and blue light LB.

[0011] 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 combining optical system 5, and a projection optical device 6.

[0012] The illumination device 2 emits white illumination light WL toward the color separation optical system 3. The color separation optical system 3 separates the white illumination light WL 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 reflecting mirror 8a, a second reflecting mirror 8b, a third reflecting mirror 8c, a first relay lens 9a, and a second relay lens 9b.

[0013] The first dichroic mirror 7a separates the illumination light WL from the illumination device 2 into red light LR and other light (green light LG and blue light LB). The first dichroic mirror 7a transmits the red light LR and reflects the other light (green light LG and blue light LB). On the other hand, the second dichroic mirror 7b separates the other light into green light LG and blue light LB. The second dichroic mirror 7b reflects the green light LG and transmits the blue light LB.

[0014] The first reflecting 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 reflecting mirror 8b and the third reflecting mirror 8c are disposed in the optical path of the blue light LB and reflect the blue light LB transmitted through the second dichroic mirror 7b toward the optical modulation device 4B. In addition, the green light LG is reflected by the second dichroic mirror 7b toward the optical modulation device 4G.

[0015] The first relay lens 9a and the second relay lens 9b are disposed on the light exit side of the second dichroic mirror 7b in the optical path of the blue light LB. The first relay lens 9a and the second relay lens 9b correct a difference in illumination distribution 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.

[0016] 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.

[0017] For example, a transmissive liquid crystal panel is used for the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B. Furthermore, a polarizing plate (not shown) is arranged on the entrance side and the exit side of each of the liquid crystal panels, and is configured to pass only linearly polarized light in a specific direction.

[0018] Field lenses 10R, 10G, and 10B are disposed on the incident sides of the optical modulation device 4R, the optical modulation device 4G, and the optical modulation device 4B, respectively. The field lenses 10R, 10G, and 10B collimate the main rays of the red light LR, the green light LG, and the blue light LB incident on the optical modulation device 4R, the optical modulation device 4G, and the optical modulation device 4B, respectively.

[0019] The combining optical system 5 receives the image light emitted from the light modulation device 4R, the light modulation device 4G, and the light modulation device 4B, combines the image light corresponding to the red light LR, the green light LG, and the blue light LB, and emits the combined image light toward the projection optical device 6. The combining optical system 5 may be, for example, a cross dichroic prism.

[0020] The projection optical device 6 is composed of 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 image is displayed on the screen SCR.

[0021] An example of the lighting device 2 of this embodiment will be described. FIG. 2 is a diagram showing a schematic configuration of the lighting device 2. As shown in FIG. 2, the illumination device 2 includes a light source 11, a first optical system 12, a dichroic mirror (reflective member) 13, a second optical system 14, a wavelength conversion element 15, and a uniforming illumination optical system 16. The light source 11, the first optical system 12, and the dichroic mirror 13 are arranged along a light source optical axis AX1. The wavelength conversion element 15, the second optical system 14, the dichroic mirror 13, and the uniforming illumination optical system 16 are arranged along an illumination optical axis AX of the illumination device 2. The light source optical axis AX1 and the illumination optical axis AX are perpendicular to each other.

[0022] The light source 11 emits the first light B. The first light B is light having a first wavelength band. The first wavelength band of the first light B is, for example, 450 to 460 nm, and the peak wavelength of the emission intensity is, for example, 455 nm. That is, the first light B is blue light. The light source 11 is composed of at least one semiconductor laser. The semiconductor laser may emit the first light B having a peak wavelength other than 455 nm. The light source 11 includes a collimator lens (not shown) provided corresponding to the semiconductor laser. Thereby, the light source 11 converts the first light B emitted from the semiconductor laser into parallel light and emits it.

[0023] The first light B emitted from the light source 11 is incident on the first optical system 12. The first optical system 12 includes at least one convex lens, and causes the first light B to be incident on the dichroic mirror 13 in a condensed state.

[0024] The dichroic mirror 13 is disposed near the focal point of the first optical system 12. As a result, the first light B is incident on the dichroic mirror 13 in a state where it is condensed and the light beam diameter is substantially minimized. By making the first light B incident on the dichroic mirror 13 in this condensed state, the size of the dichroic mirror 13 can be reduced.

[0025] The dichroic mirror 13 has optical properties of reflecting a first light B having a first wavelength band and transmitting a second light Y having a second wavelength band emitted from a wavelength conversion element 15 described later. The dichroic mirror 13 is made of a dielectric multilayer film.

[0026] In this embodiment, the first light B is incident on the dichroic mirror 13 in a divergent state. The first light B reflected by the dichroic mirror 13 is incident on the second optical system 14. The second optical system 14 includes at least one convex lens, and collimates the first light B incident as divergent light. The first light B collimated by the second optical system 14 is incident on the wavelength conversion element 15. That is, in this embodiment, the first light B is incident on the wavelength conversion element 15 as parallel light.

[0027] FIG. 3 is a cross-sectional view showing the configuration of the wavelength conversion element 15. As shown in FIG. 3, the wavelength conversion element 15 includes a substrate 21, a reflective layer 22, a wavelength conversion layer 23, a structure 40, and a half mirror layer (optical layer) 25. The substrate 21 has an upper surface 21a. The substrate 21 is a support substrate that supports the reflective layer 22, the wavelength conversion layer 23, the structure 40, and the half mirror layer 25, and is also a heat dissipation substrate that dissipates heat conducted from the wavelength conversion layer 23. The substrate 21 can be made of a material having high thermal conductivity, such as metal or ceramics.

[0028] The reflective layer 22 is provided on the upper surface 21a of the substrate 21. That is, the reflective layer 22 is located between the substrate 21 and the wavelength conversion layer 23, and reflects light incident from the wavelength conversion layer 23 toward the wavelength conversion layer 23. The reflective layer 22 is composed of a laminated film including a dielectric multilayer film, a metal mirror, an enhanced reflection film, and the like.

[0029] The wavelength conversion layer 23 is provided on the reflective layer 22. The wavelength conversion layer 23 has an upper surface 23a on which the first light B is incident and a lower surface 23b different from the upper surface 23a. The wavelength conversion layer 23 converts the first light B in a first wavelength band into second light Y having a second wavelength band different from the first wavelength band.

[0030] The wavelength conversion layer 23 may contain a ceramic phosphor or a single crystal phosphor. The second wavelength band is, for example, 500 to 680 nm. That is, the second light Y is yellow light containing a green light component and a red light component.

[0031] The wavelength conversion layer 23 contains, for example, an yttrium-aluminum-garnet (YAG) phosphor. Taking YAG:Ce containing cerium (Ce) as an activator as an example, the wavelength conversion layer 23 can be made of a material obtained by mixing raw material powders containing constituent elements such as Y2O3, Al2O3, and CeO3 and reacting them in a solid state, Y-Al-O amorphous particles obtained by a wet method such as a coprecipitation method or a sol-gel method, or YAG particles obtained by a gas phase method such as a spray drying method, a flame pyrolysis method, or a thermal plasma method. In addition, when a porous sintered body is used as the wavelength conversion layer 23, light is scattered inside the phosphor and is difficult to propagate in the lateral direction, which is desirable from the viewpoint of light utilization efficiency.

[0032] The structure 40 is provided on the upper surface 23a of the wavelength conversion layer 23, and scatters a part of the first light B. The structure 40 includes a plurality of structures 45 and a plurality of flat portions 43. The plurality of structures 45 includes a first structure 41 and a second structure 42. The flat portion 43 is provided between the first structure 41 and the second structure 42. The first structure 41 and the second structure 42 are two adjacent structures among the plurality of structures 45.

[0033] In this embodiment, the first structural portion 41 and the second structural portion 42 have a quadrangular pyramid shape. Hereinafter, when the first structural portion 41 and the second structural portion 42 are not particularly distinguished from each other, the first structural portion 41 and the second structural portion 42 will be simply referred to as "structural portion 45."

[0034] In this embodiment, the structure 40 is formed separately from the wavelength conversion layer 23. For the structure 40 of this embodiment, a method of forming a dielectric by, for example, a deposition method, a sputtering method, a CVD method, a coating method, or the like, and then processing it by photolithography is suitable. Other methods such as a printing method or a transfer method such as nanoimprinting may also be used. The structure 40 is preferably made of a material that has low optical absorption and is chemically stable. That is, the structure 40 is made of a material with a refractive index in the range of 1.3 to 2.5, and for example, SiO2, SiON, TiO2, or the like can be used. For example, if the structure 40 is made of SiO2, it can be processed with high precision by wet or dry etching.

[0035] The half mirror layer 25 is provided on the structure 40, and reflects a part of the first light B, transmits another part of the first light B, and transmits the second light Y. The reflectance of the half mirror layer 25 can be designed with a high degree of freedom in terms of reflectance and wavelength characteristics depending on the material and layer structure. The half mirror layer 25 covers the structure portion 45 and the flat portion 43.

[0036] The half mirror layer 25 of this embodiment is made of a dielectric multilayer film to suppress light absorption. The material used for the dielectric multilayer film is a chemically stable and commonly used material, for example, any one of MgF2, SiO2, Al2O3, Y2O3, CeO2, HfO2, La2O3, ZrO2, Ta2O5, Nb2O5, and TiO2 is preferable. Note that MgF2 and SiO2 are suitable as low refractive index materials, and Al2O3, Y2O3, CeO2, HfO2, La2O3, ZrO2, Ta2O5, Nb2O5, and TiO2 are suitable as intermediate to high refractive index materials. The half mirror layer 25 of this embodiment is made of a dielectric multilayer film in which, for example, SiO2 and TiO2 are alternately stacked in multiple layers.

[0037] The half mirror layer 25 includes a first layer 25a and a second layer 25b. The first layer 25a is a layer of the half mirror layer 25 that covers the structural portion 45. The second layer 25b is a layer of the half mirror layer 25 that covers the flat portion 43.

[0038] The structure 40 of this embodiment has a first reflectance for the first light B in a structural portion 45 in which the first layer 25a is provided. Specifically, the first structural portion 41 and the second structural portion 42 each have a first reflectance for the first light B by having their surfaces covered with the first layer 25a.

[0039] Furthermore, in the structure 40 of this embodiment, the flat portion 43 on which the second layer 25b is provided has a second reflectance different from the first reflectance for the first light B. Specifically, the flat portion 43 has a surface covered with the second layer 25b, and thus has the second reflectance for the first light B. In this embodiment, the first reflectance is greater than the second reflectance as described below.

[0040] In this embodiment, the thickness of the first layer 25a is smaller than the thickness of the second layer 25b. Here, the thickness of the first layer 25a means the thickness in the normal direction to the surface of the first structural portion 41 or the second structural portion 42, and the thickness of the second layer 25b means the thickness in the normal direction to the surface of the flat portion 43.

[0041] The half mirror layer 25 is formed by, for example, a deposition method, a sputtering method, a CVD method, a coating method, or the like. The surface of the structure portion 45 is inclined with respect to the surface of the flat portion 43. Therefore, for example, by using a deposition method, as described above, it is possible to easily realize a configuration in which the film thickness of the first layer 25a covering the structure portion 45 is thinner than the film thickness of the second layer 25b covering the flat portion 43 by the same process. Furthermore, when the half mirror layer 25 is formed by the sputtering method or the CVD method, the difference in adhesion probability of the film-forming particles is smaller and the film thickness distribution is smaller than that by the vapor deposition method, but the half mirror layer 25 having the same reflection characteristics as that by the vapor deposition method can be formed by calculating and designing the film thickness ratio suitable for each device. The half mirror layer 25 may also be formed by the ALD (Atomic Layer Deposition) method. In this case, the half mirror layer 25 can be formed by designing the reflection angle characteristics by utilizing the difference in the incidence angle of the structure portion 45 and the flat portion 43 with respect to the film formation surface.

[0042] Next, the optical characteristics of the half mirror layer 25 of this embodiment will be described. Fig. 4A is a diagram showing the surface reflection spectrum of the second layer 25b covering the flat portion 43. Fig. 4A shows the reflectance at the surface of the second layer 25b for light incident at a predetermined incident angle. In Fig. 4A, the horizontal axis shows the wavelength of light incident on the second layer 25b, and the vertical axis shows the reflectance at the surface of the second layer 25b. Note that Fig. 4A shows the reflectance of light incident at incident angles of 0 degrees and 10 degrees. Fig. 4B is a diagram showing the reflectance angle characteristics of the second layer 25b of the first light B. In Fig. 4B, the horizontal axis represents the incident angle of the first light B, and the vertical axis represents the reflectance.

[0043] In this embodiment, since the second layer 25b is provided on the surface of the flat portion 43, the first light B is incident on the surface of the second layer 25b in a perpendicular direction, for example, with an angle distribution of 0±10 degrees. As shown in FIG. 4A, the second layer 25b of this embodiment has a low reflectance for a light ray (incident angle of 0 or 10 degrees) in a substantially perpendicular direction in the second layer 25b in a first wavelength band (450 to 460 nm) of the first light B. That is, the second layer 25b is designed so that the peak P of the transmittance for light incident on the second layer 25b in a substantially perpendicular direction is in the first wavelength band. That is, the second layer 25b is designed so that the reflectance for light in the first wavelength band incident on the second layer 25b in a substantially perpendicular direction is the lowest. 4B, the second layer 25b has a reflectance of about 5% for the first light B incident on the second layer 25b at an angle ranging from 0 degrees to 10 degrees. That is, in this embodiment, the reflectance of the first light B by the second layer 25b provided on the surface of the flat portion 43 is about 5%.

[0044] In this embodiment, the inclination angle of the surface of the structure 45 with respect to the surface of the flat portion 43 is set to, for example, 30 degrees. As described above, the first light B is incident on the surface of the structure 45 with an angle distribution of 0±10 degrees. At this time, the first light B is incident on the surface of the first layer 25a provided on the structure 45 from an oblique direction with an incident angle of 20 to 40 degrees.

[0045] Fig. 5A is a diagram showing the surface reflection spectrum of the first layer 25a covering the structure 45. Fig. 5A shows the reflectance of the surface of the first layer 25a for the first light B incident at an incident angle of 20 to 40 degrees. In Fig. 5A, the horizontal axis shows the wavelength of the light incident on the first layer 25a, and the vertical axis shows the reflectance at the surface of the first layer 25a. Note that Fig. 5A shows the reflectance of the light incident at incident angles of 20 degrees, 30 degrees, and 40 degrees, respectively. Fig. 5B is a diagram showing the reflectance angle characteristics of the first layer 25a of the first light B. In Fig. 5B, the horizontal axis represents the incident angle of the first light B, and the vertical axis represents the reflectance.

[0046] Generally, the dielectric multilayer film, which is the material for forming the half mirror layer 25, has a characteristic that the reflection spectrum shifts to the short wavelength side as the film thickness becomes thinner. Also, the dielectric multilayer film has a characteristic that the reflection spectrum shifts to the short wavelength side for light incident from an oblique direction.

[0047] In this embodiment, the first layer 25a is thinner than the second layer 25b as described above. The first light B is incident on the first layer 25a from an oblique direction. Therefore, the reflection spectrum of the first light B in the first layer 25a is shifted to the short wavelength side compared to the reflection spectrum of the first light B in the second layer 25b.

[0048] As shown in FIG. 4A, the reflection spectrum in the second layer 25b has the lowest reflectance for the first light B in the first wavelength band (450 to 460 nm). Therefore, the wavelength band of light in which the reflectance is lowest in the first layer 25a is shifted to a wavelength band lower than the first wavelength band. As shown in FIG. 5A, the wavelength band of light in which the reflectance is lowest in the first layer 25a is about 400 nm, which is lower than the first wavelength band. In other words, the reflectance for the first light B having the first wavelength band in the first layer 25a is higher than the reflectance for the first light B in the second layer 25b. As shown in FIG. 5B, in this embodiment, the first layer 25a has a reflectance of about 16% for the first light B incident on the first layer 25a at an angle in the range of 20 degrees to 40 degrees.

[0049] In this manner, in the half mirror layer 25 of the present embodiment, the wavelength band in which the reflectance of the light incident on the flat portion 43 is lowest corresponds to the first light B, and the reflection spectrum of the light incident on the structural portion 45 is shifted toward the shorter wavelength side, so that the reflectance of the first light B in the first layer 25a is greater than the reflectance of the first light B in the second layer 25b.

[0050] 6A and 6B are enlarged views of the main part for explaining the first light B reflected by the wavelength conversion element 15. In FIG. 6A and FIG. 6B, the axis passing through the center of the structure 45 having a quadrangular pyramid shape is the central axis O. FIG. 6A is a plan view showing the main configuration of the wavelength conversion element 15, and FIG. 6B is a cross-sectional view taken along the line BB in FIG. 6A, which passes through the central axis O of the structure 45. In FIG. 6A, the half mirror layer 25 is omitted for ease of viewing. In the following description, of the first light B incident on the structure 40 provided on the upper surface 23a of the wavelength conversion layer 23, the component incident on the structure 45 is referred to as the first light Ba, and the component incident on the flat portion 43 is referred to as the first light Bb.

[0051] As described above, in the wavelength conversion element 15 of the present embodiment, the reflectance of the structure portion 45 is higher than that of the flat portion 43. Therefore, as shown in Figures 6A and 6B, according to the wavelength conversion element 15 of the present embodiment, of the first light B incident on the structure 40 provided on the upper surface 23a of the wavelength conversion layer 23, the first light Ba incident on the structure portion 45 can be reflected relatively more, and the first light Bb incident on the flat portion 43 can be reflected relatively less.

[0052] 6B, since the surface of the structure 45 is an inclined surface with respect to the surface of the flat portion 43, the first light Ba incident on the structure 45 is reflected in an oblique direction away from the vertical direction. That is, the wavelength conversion element 15 of the present embodiment scatters and reflects the first light B so as to reflect it more in an oblique direction than in the vertical direction.

[0053] In this embodiment, since the structure 45 has a quadrangular pyramid shape, the directions of the four side surfaces differ by 90 degrees when viewed from a direction along the central axis O. Therefore, the structure 45 can isotropically scatter and reflect the first light Ba in four directions around the central axis O. Hereinafter, the first light B that is scattered and reflected from the wavelength conversion element 15 will be referred to as scattered reflected light.

[0054] Fig. 7 is a diagram showing the light distribution characteristic of the diffuse reflected light B1 by the wavelength conversion element 15 of this embodiment. In Fig. 7, the vertical axis defines the light distribution in the 0 degree direction of the diffuse reflected light B1, and the horizontal axis defines the light distribution in the ±90 degree directions of the diffuse reflected light B1. Note that Fig. 7 shows the light distribution characteristic of the wavelength conversion element 15 of this embodiment as an example, and illustrates the light distribution characteristic of a wavelength conversion element in which only the structure 40 is provided on the upper surface 23a of the wavelength conversion layer 23 and no half mirror layer 25 is provided, as a comparative example.

[0055] As shown in FIG. 7, in the wavelength conversion element of the comparative example, it is found that the light distribution of the scattered reflected light B1 is approximately uniform over the entire range of oblique directions from the 0 degree direction to the range of 15 to 60 degrees. In contrast, the wavelength conversion element 15 of this embodiment emits light having a light distribution that contains more components in oblique directions in the range of 15 to 60 degrees than in the vertical direction along the 0 degree direction as scattered reflected light B1.

[0056] In this way, according to the wavelength conversion element 15 of this embodiment, the diffuse reflected light B1 can be reflected more in the oblique direction than in the vertical direction, as shown in Fig. 3. Note that in Fig. 3, for ease of understanding, the light beam width of the diffuse reflected light B1 is shown to be wider in the oblique direction than in the vertical direction.

[0057] Since the structure 40 of this embodiment is made of a material with low light absorption, the second light Y is suppressed from being reflected on the surface of the structure 40. Therefore, in the wavelength conversion element 15 of this embodiment, the second light Y generated in the wavelength conversion layer 23 transmits through the structure 40 and the half mirror layer 25 and is efficiently emitted to the outside.

[0058] According to the wavelength conversion element 15 of the present embodiment, white illumination light WL including the scattered reflected light B1 and the second light Y can be emitted toward the second optical system 14. The illumination light WL is substantially collimated by the second optical system 14. The illumination light WL transmitted through the second optical system 14 passes through the dichroic mirror 13 arranged on the illumination optical axis AX.

[0059] Here, the dichroic mirror 13 has the optical property of reflecting the first light B and transmitting the second light Y. Therefore, the second light Y included in the illumination light WL passes through the dichroic mirror 13 and travels toward the homogenizing illumination optical system 16. Since the second light Y passes through the dichroic mirror 13, the optical loss of the second light Y caused by the dichroic mirror 13 can be reduced.

[0060] On the other hand, the scattered reflected light B1 contained in the illumination light WL is light in the same first wavelength band as the first light B, and is therefore reflected by the dichroic mirror 13. In this embodiment, the scattered reflected light B1 contained in the illumination light WL has a light distribution that includes more oblique components than vertical components as described above. Therefore, most of the light rays contained in the scattered reflected light B1 head toward the uniformizing illumination optical system 16 so as to avoid the dichroic mirror 13 that is positioned perpendicular to the wavelength conversion element 15.

[0061] This suppresses the amount of scattered reflected light B1 incident on the dichroic mirror 13, thereby reducing the proportion of scattered reflected light B1 that is not effectively used as illumination light WL due to being reflected by the dichroic mirror 13. Furthermore, in this embodiment, the first light B is incident on the dichroic mirror 13 in a condensed state, thereby making the dichroic mirror 13 smaller. Therefore, the amount of scattered reflected light B1 incident on the dichroic mirror 13 can be further reduced.

[0062] The uniformizing illumination optical system 16 into which the illumination light WL is incident includes an integrator optical system 31, a polarization conversion element 32, and a superimposing optical system 33. The integrator optical system 31 includes a first multi-lens array 31a and a second multi-lens array 31b.

[0063] The polarization conversion element 32 is configured by arranging a polarization separation film and a retardation plate in an array. The polarization conversion element 32 aligns the polarization direction of the illumination light WL in a predetermined direction. Specifically, the polarization conversion element 32 aligns the polarization direction of the illumination light WL to the direction of the transmission axis of the incident side polarizer of the optical modulation devices 4R, 4G, and 4B.

[0064] As a result, the polarization directions of the red light LR, green light LG, and blue light LB obtained by separating the illumination light WL transmitted through the polarization conversion element 32 coincide with the transmission axis directions of the incident-side polarizing plates of the optical modulation devices 4R, 4G, and 4B. Therefore, the red light LR, green light LG, and blue light LB are not blocked by the incident-side polarizing plates, and are incident on the image forming areas of the optical modulation devices 4R, 4G, and 4B, respectively.

[0065] The superimposing optical system 33, together with the second multi-lens array 31b, forms an image of each small lens of the first multi-lens array 31a in the vicinity of the image forming area of ​​each of the light modulation devices 4R, 4G, and 4B.

[0066] According to the lighting device 2 of the present embodiment, the light utilization efficiency of the illumination light WL can be improved, and the brightness of the illumination light WL can be improved and power consumption can be reduced, or heat generation within the device due to light loss can be suppressed.

[0067] (effect) The wavelength conversion element 15 of the present embodiment includes a substrate 21, a reflective layer 22 provided on an upper surface 21a of the substrate 21, a wavelength conversion layer 23 provided opposite the reflective layer 22 and configured to convert a first light B in a first wavelength band into a second light Y in a second wavelength band different from the first wavelength band, a structure 40 provided opposite the wavelength conversion layer 23 and configured to scatter a part of the first light B in the first wavelength band, and a second light Y provided opposite the structure 40 and configured to reflect a part of the first light B in the first wavelength band and transmit another part of the first light B in the first wavelength band, and and a half mirror layer 25 that transmits a second light Y of a second wavelength band, and the structure 40 includes a first structure portion 41, a second structure portion 42, and a flat portion 43 provided between the first structure portion 41 and the second structure portion 42, and the first layer 25a provided in the first structure portion 41 and the second structure portion 42 has a first reflectance for the first light B of the first wavelength band, and the second layer 25b provided in the flat portion 43 has a second reflectance for the first light B of the first wavelength band that is different from the first reflectance. In this embodiment, the first reflectance is greater than the second reflectance.

[0068] In the wavelength conversion element 15 of this embodiment, the first reflectance of the first layer 25a is higher than the second reflectance of the second layer 25b. As a result, the structure 40 generates the scattered reflected light B1 having a light distribution including more components in the oblique direction than in the vertical direction. The scattered reflected light B1 travels so as to avoid the dichroic mirror 13. Therefore, according to the wavelength conversion element 15 of this embodiment, the light use efficiency of the first light B can be improved by reducing the light loss caused by the dichroic mirror 13.

[0069] In the wavelength conversion element 15 of this embodiment, the half mirror layer 25 has a first layer 25a provided in the first structural portion 41 and the second structural portion 42 having a first film thickness, and a second layer 25b provided in the flat portion 43 having a second film thickness, and the first film thickness is thinner than the second film thickness.

[0070] In the first layer 25a having a small thickness, the reflection spectrum of the first light B is shifted to the short wavelength side. This makes it possible to realize a configuration in which the first reflectance of the first layer 25a is higher than the second reflectance of the second layer 25b. Therefore, it is possible to generate the scattered reflected light B1 with a light distribution that contains more components in the oblique direction than in the vertical direction as described above.

[0071] In the wavelength conversion element 15 of this embodiment, the first structure portion 41 and the second structure portion 42 have a quadrangular pyramid shape.

[0072] According to the first structural portion 41 and the second structural portion 42 each having a quadrangular pyramid shape, it is possible to generate the scattered reflected light B1 by isotropically scattering the first light B.

[0073] In the wavelength conversion element 15 of this embodiment, the structures 40 are made of a material having a refractive index in the range of 1.3 to 2.5.

[0074] According to this configuration, the structure 40 can be made of a material that has low optical absorption and is chemically stable.

[0075] In the wavelength conversion element 15 of this embodiment, the half mirror layer 25 is made of a dielectric multilayer film.

[0076] According to this configuration, the half mirror layer 25 that suppresses light absorption can be formed.

[0077] In the wavelength conversion element 15 of this embodiment, the dielectric multilayer film may be configured to contain any one of MgF2, SiO2, Al2O3, Y2O3, CeO2, HfO2, La2O3, ZrO2, Ta2O5, Nb2O5, and TiO2.

[0078] According to this configuration, the half mirror layer 25 can be formed so as to suppress light absorption and to be chemically stable.

[0079] The lighting device 2 of this embodiment includes the above-mentioned wavelength conversion element 15, a light source 11 that emits a first light B in a first wavelength band, and a dichroic mirror 13 that reflects the first light B in the first wavelength band emitted from the light source 11 toward the wavelength conversion element 15.

[0080] According to the illumination device 2 of the present embodiment, the amount of scattered reflected light B1 incident on the dichroic mirror 13 is suppressed, so that the light utilization efficiency of the illumination light WL can be improved.

[0081] In the illumination device 2 of the present embodiment, the dichroic mirror 13 may be configured to transmit the second light Y in the second wavelength band.

[0082] According to this configuration, the optical loss of the second light Y caused by the dichroic mirror 13 can be reduced.

[0083] The projector 1 of this embodiment includes an illumination device 2, light modulation devices 4R, 4G, and 4B that modulate light from the illumination device 2 according to image information, and a projection optical device 6 that projects the light modulated by the light modulation devices 4R, 4G, and 4B.

[0084] According to the projector 1 of the present embodiment, since it is equipped with the illumination device 2 that improves the light utilization efficiency of the illumination light WL, it is possible to provide a projector that has high light efficiency and displays bright images.

[0085] 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. For example, in the above embodiment, the structure 40 is formed separately from the wavelength conversion layer 23, but the structure 40 may be formed integrally with the wavelength conversion layer 23. FIG. 8 is a diagram showing a configuration in which the structure 40 and the wavelength conversion layer 23 are integrally formed. According to a configuration in which the structure 40 is directly formed on the upper surface 23a of the wavelength conversion layer 23 as shown in FIG. 8, the process of forming the structure 40 can be omitted, and the cost of the wavelength conversion element 15 can be reduced. In addition, since the structure 40 and the wavelength conversion layer 23 have the same refractive index, there is no interfacial reflection between the structure 40 and the wavelength conversion layer 23, so that light is less likely to escape in the lateral direction, and as a result, the etendue can be reduced.

[0086] Furthermore, the shape of the structural portion 45 is not limited to a quadrangular pyramid shape, and may be a convex lens shape or a concave lens shape. Furthermore, in the structure 40 of the above embodiment, a plurality of structural portions 45 having the same shape are arranged at equal pitches, but the structure 40 may be configured by randomly arranging structural portions 45 having the same or different shapes. Furthermore, in the structural portion 45, the first structural portion 41 and the second structural portion 42 may have different shapes.

[0087] In addition, in the above embodiment, the wavelength conversion element 15 adopts a fixed structure in which the wavelength conversion layer 23 does not move with respect to the first light B, but it may also adopt a wheel-type structure in which the wavelength conversion layer 23 rotates with respect to the first light B.

[0088] In addition, the specific description of the shape, number, arrangement, material, etc. of each component of the lighting device and the projector is not limited to the above embodiment and can be changed as appropriate. In the above embodiment, an example in which the lighting device according to the present invention is mounted on a projector using a liquid crystal light valve is shown, but this is not limited to this. The lighting device according to the present invention may be applied to a projector using a digital micromirror device as a light modulation device. In addition, the projector does not need to have multiple light modulation devices, and may have only one light modulation device.

[0089] In the above embodiment, the illumination device according to the present invention is applied to a projector, but the present invention is not limited to this. The illumination device according to the present invention can also be applied to lighting fixtures, automobile headlights, and the like.

[0090] The wavelength conversion element according to one aspect of the present invention may have the following configuration. A wavelength conversion element according to one embodiment of the present invention comprises a substrate, a reflective layer provided on the substrate, a wavelength conversion layer provided on the reflective layer for converting light of a first wavelength band to light of a second wavelength band different from the first wavelength band, a structure provided on the wavelength conversion layer for scattering a portion of the light of the first wavelength band, and an optical layer provided on the structure for reflecting a portion of the light of the first wavelength band, transmitting another portion of the light of the first wavelength band, and transmitting light of the second wavelength band, wherein the structure includes a first structural portion, a second structural portion, and a flat portion provided between the first structural portion and the second structural portion, wherein the optical layer provided on the first structural portion and the second structural portion has a first reflectance for light of the first wavelength band, and the optical layer provided on the flat portion has a second reflectance for light of the first wavelength band different from the first reflectance.

[0091] In the wavelength conversion element according to one aspect of the present invention, the first reflectance may be greater than the second reflectance.

[0092] In one embodiment of the wavelength conversion element of the present invention, the optical layer provided in the first structure portion and the second structure portion has a first film thickness, and the optical layer provided in the flat portion has a second film thickness different from the first film thickness, and the first film thickness may be thinner than the second film thickness.

[0093] In the wavelength conversion element according to one aspect of the present invention, the first structure and the second structure may have a quadrangular pyramid shape.

[0094] In the wavelength conversion element according to one aspect of the present invention, the structures may be configured to be made of a material having a refractive index in the range of 1.3 to 2.5.

[0095] In the wavelength conversion element according to one aspect of the present invention, the optical layer may be composed of a dielectric multilayer film.

[0096] In the wavelength conversion element according to one aspect of the present invention, the dielectric multilayer film may contain any one of MgF2, SiO2, Al2O3, Y2O3, CeO2, HfO2, La2O3, ZrO2, Ta2O5, Nb2O5, and TiO2.

[0097] In the wavelength conversion element according to one aspect of the present invention, the structure may be integrally formed with the wavelength conversion layer.

[0098] The lighting device according to one aspect of the present invention may have the following configuration. An illumination device of the present invention includes the above-mentioned wavelength conversion element, a light source that emits light of a first wavelength band, and a reflecting member that reflects the light of the first wavelength band emitted from the light source toward the wavelength conversion element.

[0099] In the light source device according to one aspect of the present invention, the reflective member may be configured to transmit light in the second wavelength band.

[0100] A projector according to one aspect of the invention may have the following configuration. A projector according to one embodiment of the present invention comprises an illumination device according to one embodiment of the present invention, a light modulation device that modulates light from the illumination device in accordance with image information, and a projection optical device that projects the light modulated by the light modulation device. [Explanation of symbols]

[0101] 1...projector, 2...illumination device, 4B, 4G, 4R...light modulation device, 6...projection optical device, 11...light source, 13...dichroic mirror (reflective member), 15...wavelength conversion element, 21...substrate, 21a...upper surface, 22...reflective layer, 23...wavelength conversion layer, 25...half mirror layer (optical layer), 25a...first layer, 25b...second layer, 40...structure, 41...first structural portion, 42...second structural portion, 43...flat portion, 45...structural portion.

Claims

1. A substrate; A reflective layer provided on the substrate; a wavelength conversion layer provided on the reflective layer and configured to convert light in a first wavelength band into light in a second wavelength band different from the first wavelength band; a structure provided in the wavelength conversion layer for scattering a portion of the light in the first wavelength band; an optical layer provided on the structure, which reflects a portion of the light in the first wavelength band, transmits another portion of the light in the first wavelength band, and transmits the light in the second wavelength band; the structure includes a first structural portion, a second structural portion, and a flat portion provided between the first structural portion and the second structural portion; a first layer of the optical layer provided on the first structure and the second structure has a first reflectance for light in the first wavelength band, a second layer of the optical layer provided in the flat portion has a second reflectance for light in the first wavelength band that is different from the first reflectance, The scattered reflected light that is scattered and reflected from the wavelength conversion layer on which the structures and the optical layer are provided has a light distribution that includes more components in oblique directions than in a direction perpendicular to the surface of the second layer. A wavelength conversion element comprising:

2. The first reflectance is greater than the second reflectance.

2. The wavelength conversion element according to claim 1 .

3. the first layer of the optical layer has a first thickness; the second layer of the optical layer has a second thickness different from the first thickness; The first film thickness is smaller than the second film thickness.

3. The wavelength conversion element according to claim 1 or 2.

4. The first structure and the second structure have a quadrangular pyramid shape.

4. The wavelength conversion element according to claim 1, wherein the wavelength conversion element is a reflective layer.

5. The structure is made of a material having a refractive index in the range of 1.3 to 2.

5.

5. The wavelength conversion element according to claim 1, wherein the wavelength conversion element is a reflective layer.

6. The optical layer is composed of a dielectric multilayer film.

6. The wavelength conversion element according to claim 1, wherein the wavelength conversion element is a reflective layer.

7. The dielectric multilayer film is made of MgF ２ , SiO ２ , Al ２ O ３ , Y ２ O ３ , CeO ２ , HfO ２ , La ２ O ３ , ZrO ２ , Ta ２ O ５ , Nb ２ O ５ , TiO ２ Contains any of the following:

7. The wavelength conversion element according to claim 6.

8. The structure and the wavelength conversion layer are a single piece.

8. The wavelength conversion element according to claim 1, wherein the wavelength conversion element is a reflective layer.

9. A wavelength conversion element according to any one of claims 1 to 8, a light source that emits light in the first wavelength band; a reflecting member that reflects the light of the first wavelength band emitted from the light source toward the wavelength conversion element. A lighting device characterized by:

10. The reflecting member transmits light of the second wavelength band.

10. The lighting device according to claim 9.

11. The lighting device according to claim 9 or 10, a light modulation device that modulates the light from the illumination device in accordance with image information; a projection optical device that projects the light modulated by the light modulation device. A projector characterized by:

Images