JP2020112590A - Wavelength conversion element, lighting device and projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable wavelength conversion element.
A wavelength conversion element 32 includes a base material 43 having a reflection surface 43r, a first surface 47a on which excitation light of a first wavelength band is incident, and a second surface 42b opposite to the first surface 47a. And a wavelength conversion unit 32 that converts the excitation light into fluorescence in the second wavelength band, a bonding unit 37 that bonds the wavelength conversion unit 32 and the base material 43, a reflection surface 43r, and a second surface. And a liquid 38 contained in a space surrounded by the reflection surface 43r, the second surface 42b, and the bonding portion 37. At least a part of the portion of the first surface 47a facing the liquid 38 is an incident region T of the excitation light E.
[Selection diagram] Fig. 4

Description

The present invention relates to a wavelength conversion element, a lighting device, and a projector.

In recent years, an illumination device using a wavelength conversion element such as a rotating fluorescent plate has been proposed as an illumination device for a projector. The rotating fluorescent plate emits fluorescence by irradiating the fluorescent material layer with excitation light while the substrate having the fluorescent material layer is rotated. As a result, the illumination device emits illumination light containing fluorescence.

The following Patent Document 1 discloses a "wavelength conversion element" including a substrate, a reflection enhancing film layer, a ring-shaped phosphor layer, and an adhesive layer. In this wavelength conversion element, the increased reflection film layer is provided on one surface of the substrate, and the phosphor layer is bonded to the increased reflection film layer via the adhesive layer.

JP, 2018-25750, A

The temperature of the wavelength conversion element rises when irradiated with the excitation light. Therefore, when the phosphor layer is fixed to the substrate via the adhesive layer as in the wavelength conversion element of Patent Document 1, the heat of the phosphor layer is adhered by heat in the process of being transferred to the substrate via the adhesive layer. The layers could be damaged. As a result, the reliability of the wavelength conversion element may decrease.

In order to solve the above problems, a wavelength conversion element according to one aspect of the present invention includes a base material having a reflective surface, a first surface on which excitation light of a first wavelength band is incident, and the first surface. A second surface on the opposite side, and a wavelength conversion unit that converts the excitation light into fluorescence of a second wavelength band different from the first wavelength band, the wavelength conversion unit, and the base material. And a liquid that is contained in a space surrounded by the reflecting surface, the second surface, and the joining portion, the joining portion joining the At least a part of a portion of the first surface facing the liquid is an incident region of the excitation light.

In the wavelength conversion element according to one aspect of the present invention, the wavelength conversion section has a wavelength conversion layer and a dielectric multilayer film provided on a surface of the wavelength conversion layer facing the reflection surface. Good.

In the wavelength conversion element of one aspect of the present invention, the refractive index of the liquid may be lower than the refractive index of the wavelength conversion section.

In the wavelength conversion element according to one aspect of the present invention, the refractive index of the liquid may be lower than the refractive index of the joint portion.

In the wavelength conversion element according to one aspect of the present invention, the volume of the liquid may be 50% or more of the volume of the space.

An illumination device according to one aspect of the present invention includes the wavelength conversion element according to one aspect of the present invention, and a light source that emits the excitation light toward the wavelength conversion element.

In the illuminating device according to one aspect of the present invention, the wavelength conversion element may include a rotation device that is rotatable about a rotation axis and that rotates the wavelength conversion element about the rotation axis.

A projector according to one aspect of the present invention includes a lighting device according to one aspect of the present invention, a light modulation device that modulates light from the lighting device according to image information, and a light modulated by the light modulation device. And a projection optical device for projecting.

It is a schematic structure figure showing a projector of a 1st embodiment. It is a perspective view of the wavelength converter of 1st Embodiment. It is a front view of a wavelength conversion device. FIG. 4 is a sectional view of the wavelength conversion element taken along the line IV-IV in FIG. 3. It is sectional drawing of the wavelength conversion element of 2nd Embodiment. It is a schematic block diagram which shows the projector of 3rd Embodiment. It is a front view of a wavelength conversion device. FIG. 8 is a cross-sectional view of the wavelength conversion element taken along the line VIII-VIII of FIG. 7.

[First Embodiment]
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS.
In addition, in each of the following drawings, in order to make each component easy to see, the scale of dimensions may be different depending on the component.

An example of the projector according to this embodiment will be described.
The projector of this embodiment is a projection type image display device that displays a color image on a screen (projection surface). The projector includes three light modulation devices corresponding to each color light of red light, green light, and blue light. The projector is equipped with a semiconductor laser as a light source of an illumination device, which can obtain light with high brightness and high output.

FIG. 1 is a schematic diagram showing an optical system of a projector 1 according to this embodiment.
As shown in FIG. 1, the projector 1 according to the present embodiment includes a first lighting device 100, a second lighting device 102, a color separation light guide optical system 200, a light modulation device 400R, and a light modulation device 400G. The optical modulator 400B, the light combining element 500, and the projection optical device 600 are provided.
The 1st illuminating device 100 of this embodiment corresponds to the illuminating device of a claim.

The first lighting device 100 includes a first light source 10, a collimating optical system 70, a dichroic mirror 80, a collimating condensing optical system 90, a wavelength conversion device 30, a first lens array 120, and a second lens array 130. , A polarization conversion element 140, and a superimposing lens 150.

The first light source 10 is composed of a semiconductor laser that emits blue excitation light E in the first wavelength band. The excitation light E has a wavelength range of 440 to 450 nm and a peak wavelength of emission intensity of 445 nm, for example. The first light source 10 may be composed of one semiconductor laser, or may be composed of a plurality of semiconductor lasers. The first light source 10 is arranged so that the optical axis 200ax of the laser light emitted from the first light source 10 is orthogonal to the illumination optical axis 100ax. The first light source 10 may be a semiconductor laser that emits excitation light having a peak wavelength other than 445 nm, for example, a peak wavelength of 460 nm. The first light source 10 emits the excitation light E toward the wavelength conversion element 32.
The 1st light source 10 of this embodiment respond|corresponds to the light source of a claim.

The collimating optical system 70 includes a first lens 72 and a second lens 74. The collimating optical system 70 substantially collimates the light emitted from the first light source 10. The first lens 72 and the second lens 74 are each formed of a convex lens.

The dichroic mirror 80 intersects the optical axis 200ax of the first light source 10 and the illumination optical axis 100ax at an angle of 45° in the optical path from the collimating optical system 70 to the collimating condensing optical system 90. It is arranged in the direction. The dichroic mirror 80 reflects the excitation light E composed of a blue light component and transmits the yellow fluorescence Y containing a red light component and a green light component.

The collimator condensing optical system 90 condenses the excitation light E transmitted through the dichroic mirror 80 and makes it enter the wavelength conversion layer 42 of the wavelength conversion device 30, and the fluorescence Y emitted from the wavelength conversion device 30 is substantially parallel. It has a function to change. The collimator condensing optical system 90 includes a first lens 92 and a second lens 94. The first lens 92 and the second lens 94 are each composed of a convex lens.

The second lighting device 102 includes a second light source 710, a condensing optical system 760, a diffusion plate 732, and a collimating optical system 770.

The second light source 710 is composed of a semiconductor laser having the same wavelength band as the first light source 10 of the first lighting device 100. The second light source 710 may be composed of one semiconductor laser or may be composed of a plurality of semiconductor lasers. The second light source 710 may be composed of a semiconductor laser having a wavelength band different from that of the semiconductor laser of the first light source 10.

The condensing optical system 760 includes a first lens 762 and a second lens 764. The condensing optical system 760 condenses the blue light B emitted from the second light source 710 on the diffusion surface of the diffusion plate 732 or in the vicinity of the diffusion plate 732. The first lens 762 and the second lens 764 are each formed by a convex lens.

The diffusion plate 732 diffuses the blue light B emitted from the second light source 710, and generates the blue light B having a light distribution close to the light distribution of the fluorescence Y emitted from the wavelength conversion device 30. As the diffusion plate 732, for example, ground glass made of optical glass can be used.

The collimating optical system 770 includes a first lens 772 and a second lens 774. The collimating optical system 770 substantially collimates the light emitted from the diffusion plate 732. The first lens 772 and the second lens 774 are each formed by a convex lens.

The blue light B emitted from the second illumination device 102 is reflected by the dichroic mirror 80, and is combined with the fluorescence Y emitted from the wavelength conversion device 30 and transmitted through the dichroic mirror 80 to become white light W. The white light W enters the first lens array 120. The detailed configuration of the wavelength conversion device 30 will be described later.

The first lens array 120 includes a plurality of first lenses 122 for splitting the light emitted from the dichroic mirror 80 into a plurality of partial light fluxes. The plurality of first lenses 122 are arranged in a matrix in a plane orthogonal to the illumination optical axis 100ax.

The second lens array 130 has a plurality of second lenses 132 corresponding to the plurality of first lenses 122 of the first lens array 120. The second lens array 130, together with the superimposing lens 150 in the subsequent stage, forms an image of each first lens 122 that constitutes the first lens array 120 into each of the light modulator 400R, the light modulator 400G, and the light modulator 400B. Form an image near the area. The plurality of second lenses 132 are arranged in a matrix in a plane orthogonal to the illumination optical axis 100ax.

The polarization conversion element 140 converts each of the plurality of partial light beams divided by the first lens array 120 into linearly polarized light whose polarization directions are aligned.

The superimposing lens 150 condenses the respective partial light fluxes emitted from the polarization conversion element 140, and superimposes the respective partial light fluxes in the vicinity of the image forming areas of the light modulating device 400R, the light modulating device 400G, and the light modulating device 400B. The first lens array 120, the second lens array 130, and the superimposing lens 150 form an integrator optical system that makes the intensity distribution of the light emitted from the wavelength conversion device 30 uniform within the illuminated surface.

The color separation/light guide optical system 200 includes a dichroic mirror 210, a dichroic mirror 220, a reflection mirror 230, a reflection mirror 240, a reflection mirror 250, a relay lens 260, and a relay lens 270. The color separation light guide optical system 200 separates the white light W obtained from the first lighting device 100 and the second lighting device 102 into red light LR, green light LG, and blue light LB, and red light LR, green light. The light LG and the blue light LB are guided to the corresponding light modulators 400R, 400G, 400B.

The field lens 300R is arranged between the color separation light guide optical system 200 and the light modulator 400R. The field lens 300G is arranged between the color separation light guide optical system 200 and the light modulation device 400G. The field lens 300B is arranged between the color separation light guide optical system 200 and the light modulation device 400B.

The dichroic mirror 210 transmits the red light component and reflects the green light component and the blue light component. The dichroic mirror 220 reflects a green light component and transmits a blue light component. The reflection mirror 230 reflects the red light component. The reflection mirror 240 and the reflection mirror 250 reflect the blue light component.

The red light LR that has passed through the dichroic mirror 210 is reflected by the reflection mirror 230, passes through the field lens 300R, and enters the image forming area of the light modulator 400R for red light. The green light LG reflected by the dichroic mirror 210 is further reflected by the dichroic mirror 220, passes through the field lens 300G, and enters the image forming area of the light modulator 400G for green light. The blue light LB transmitted through the dichroic mirror 220 passes through a relay lens 260, an incident side reflection mirror 240, a relay lens 270, an emission side reflection mirror 250, and a field lens 300B, and an image is formed by the blue light optical modulator 400B. Incident on the area.

The light modulation device 400R, the light modulation device 400G, and the light modulation device 400B modulate the incident color light according to image information to form image light. Each of the light modulation device 400R, the light modulation device 400G, and the light modulation device 400B is composed of a liquid crystal light valve. Although not shown, the incident-side polarization plates are arranged on the light incident sides of the light modulator 400R, the light modulator 400G, and the light modulator 400B, respectively. Emission side polarization plates are respectively arranged on the light emission sides of the light modulation device 400R, the light modulation device 400G, and the light modulation device 400B.

The light combining element 500 combines the image lights emitted from the light modulator 400R, the light modulator 400G, and the light modulator 400B to form a full-color image light. The light combining element 500 is composed of a cross dichroic prism which is formed by bonding four right-angle prisms and has a substantially square shape in a plan view. A dielectric multilayer film is formed on a substantially X-shaped interface where right-angled prisms are bonded together.

The image light emitted from the photosynthesis element 500 is enlarged and projected by the projection optical device 600 to form an image on the screen SCR. That is, the projection optical device 600 projects the light modulated by the light modulator 400R, the light modulator 400G, and the light modulator 400B. The projection optical device 600 includes a plurality of projection lenses 6.

The wavelength conversion device 30 will be described below.
FIG. 2 is a perspective view showing the wavelength conversion device 30. FIG. 3 is a front view of the wavelength conversion device 30. FIG. 4 is a cross-sectional view of the wavelength conversion element 32 taken along the line IV-IV in FIG.
As shown in FIGS. 2 and 3, the wavelength conversion device 30 of the present embodiment includes a wavelength conversion element 32 and a motor 50 (rotation device).

The wavelength conversion element 32 is rotatable around a rotation axis 35. The motor 50 rotates the wavelength conversion element 32 around the rotation axis 35. Therefore, the excitation light E emitted from the first light source 10 enters the wavelength conversion element 32 in a rotated state.

As shown in FIG. 4, the wavelength conversion element 32 of the present embodiment includes a base material 43, a wavelength conversion section 47, a joint section 37, and a liquid 38. The wavelength conversion element 32 emits the fluorescence Y toward the same side as the side on which the excitation light E is incident. That is, the wavelength conversion element 32 is a reflective wavelength conversion element.

The base material 43 includes a base material body 40 and a reflective layer 41. The base material body 40 is made of a material containing metal. As an example, the base body 40 is made of a circular plate material made of metal such as aluminum and copper having high thermal conductivity.

The reflective layer 41 is provided on the entire first surface 40 a of the base body 40. The reflective layer 41 reflects the fluorescence Y and the excitation light E emitted from the second surface 47b of the wavelength conversion unit 47. The reflective layer 41 is made of a metal having a high reflectance such as silver. The reflective layer 41 is designed to reflect the fluorescence Y and the excitation light E with high reflectance. Therefore, in order to form the smooth reflective layer 41, the first surface 40a of the base material body 40 has high smoothness. As a result, the reflective layer 41 reflects most of the fluorescent light Y in the upward direction of FIG. 4 (on the side opposite to the base body 40 ). That is, the base material 43 has the reflection surface 43r that reflects the fluorescence Y.

In addition, a protective film (not shown) may be provided on the incident side of the excitation light E of the reflective layer 41. As the protective film, for example, a light transmissive film such as SiO ₂ or Al ₂ O ₃ is used. When the protective film is provided, the reflective layer 41 is protected from the external atmosphere, and the fluorescence Y incident on the surface of the base material 43 at various angles can be reflected with high reflectance. Further, a protective layer (not shown) for protecting the reflective layer 41 from deterioration may be provided between the reflective layer 41 and the first surface 40a of the base body 40.

As shown in FIGS. 2 and 3, the wavelength conversion section 47 has an annular shape having a circular opening 47h around the rotation shaft 35 of the base material 43. That is, the wavelength conversion unit 47 is provided on the reflection surface 43r side of the base material 43 so as to surround the rotation shaft 35.

As shown in FIG. 4, the wavelength conversion section 47 includes a wavelength conversion layer 42 and a dielectric multilayer film 39. The dielectric multilayer film 39 is provided on the surface of the wavelength conversion layer 42 that faces the reflection surface 43r. The wavelength conversion unit 47 has a first surface 47a on which the excitation light E in the first wavelength band is incident and a second surface 47b opposite to the first surface 47a.

The wavelength conversion layer 42 has a first surface 42a on which the excitation light E of the first wavelength band is incident and a second surface 42b opposite to the first surface 42a. The wavelength conversion layer 42 includes a ceramic phosphor that converts the excitation light E into fluorescence Y in a wavelength band different from the wavelength band of the excitation light E. That is, the wavelength conversion layer 42 wavelength-converts the excitation light E into the fluorescence Y in the second wavelength band different from the first wavelength band. The second wavelength band is, for example, 490 to 750 nm, and the fluorescence Y is yellow light containing a red light component and a green light component. The wavelength conversion layer 42 may include a single crystal phosphor.

The wavelength conversion layer 42 contains, for example, yttrium-aluminum-garnet (YAG)-based phosphor. Taking YAG:Ce containing cerium (Ce) as an activator as an example, as the wavelength conversion layer 42, raw material powders containing constituent elements such as Y ₂ O ₃ , Al ₂ O ₃ and CeO ₃ are mixed and solidified. Phase-reacted materials, Y-Al-O amorphous particles obtained by wet methods such as coprecipitation method and sol-gel method, YAG particles obtained by gas phase methods such as spray drying method, flame pyrolysis method and thermal plasma method Can be used.

Further, the dielectric multilayer film 39 is provided on the second surface 42b of the wavelength conversion layer 42. The dielectric multilayer film 39 is formed of, for example, a film in which a plurality of SiO ₂ and TiO ₂ are alternately laminated. That is, the dielectric multilayer film 39 has a structure in which a plurality of two types of dielectric films having different refractive indexes are alternately laminated. The number of layers and the thickness of each dielectric film forming the dielectric multilayer film 39 are not particularly limited.

When the excitation light E enters the wavelength conversion section 47, heat is generated in the wavelength conversion section 47. In the present embodiment, the incident position of the excitation light E in the wavelength conversion unit 47 is temporally moved by rotating the wavelength conversion element 32 with the motor 50. As a result, the excitation light E is constantly applied to the same position of the wavelength conversion section 47, so that only a part of the wavelength conversion section 47 is locally heated and the wavelength conversion section 47 is prevented from deteriorating. In FIG. 3, the incident area of the excitation light E is indicated by a circle with a symbol T.

As shown in FIG. 4, the joining portion 37 joins the wavelength conversion portion 47 and the base material 43. Assuming that the excitation light E is incident on the joint portion 37 or the fluorescence Y is incident on the joint portion 37, in order to suppress unnecessary absorption and reflection of these lights, the joint portion 37 is made of a transparent adhesive. It is desirable to be composed of. As this type of adhesive, for example, a thermosetting silicone resin, epoxy resin, acrylic resin, inorganic adhesive or the like is used.

In the present embodiment, as shown in FIG. 3, the bonding portion 37 is provided in a region other than the incident region T of the excitation light E on the first surface 47 a of the wavelength conversion unit 47. In other words, the joining portion 37 includes an annular joining portion 37I (a joining portion 37I on the right side in FIG. 4) provided in an area on the inner circumference side of the wavelength conversion portion 47 with respect to the incident area T of the excitation light E, and the excitation light. An annular joint portion 37E (a left joint portion 37E in FIG. 4) provided in a region on the outer peripheral side of the wavelength conversion unit 47 with respect to the incident region T of E.

That is, the bonding portion 37 is not provided on the entire surface of the second surface 47b of the wavelength converting portion 47, and is formed on a part of the inner peripheral side and a part of the outer peripheral side of the second surface 47b of the wavelength converting portion 47. The wavelength converter 47 is bonded to the base material 43. As a result, in the central portion of the wavelength conversion portion 47 in the width direction W, the reflection surface 43r of the base material 43 and the second surface 47b of the wavelength conversion portion 47 are separated from each other. The width direction W of the wavelength converter 47 corresponds to the radial direction of the annular wavelength converter 47, as shown in FIG. The thickness h of the joint portion 37 is about 3 μm, and the distance between the reflecting surface 43r and the second surface 47b is also about 3 μm.

As shown in FIG. 4, the wavelength conversion element 47 and the base material 43 are bonded to each other via the bonding section 37 in a state where the reflection surface 43r and the second surface 42b are separated from each other, so that the wavelength conversion element 32 is connected to the wavelength conversion element 32. A space S surrounded by the reflection surface 43r, the second surface 42b, and the joint portion 37 is formed. In the space S, a liquid 38 having optical transparency is stored.

The refractive index of the liquid 38 is preferably lower than the refractive index of the fluorescent substance forming the wavelength conversion layer 42. When the wavelength conversion layer 42 is made of a YAG phosphor as in this embodiment, the refractive index of the liquid 38 is preferably less than 1.8, which corresponds to the refractive index of the YAG phosphor.

Furthermore, it is desirable that the refractive index of the liquid 38 be lower than the refractive index of the joint portion 37. When the joint portion 37 is made of, for example, a silicone resin, the refractive index of the liquid 38 is preferably less than 1.41 which corresponds to the refractive index of the silicone resin. Further, it is desirable that the liquid 38 is a liquid that can be degassed without causing cavitation even when a state change such as a temperature rise occurs. Examples of liquids that satisfy this type of condition include water (refractive index: 1.3334, boiling point: 100° C.), perfluorocarbon (refractive index: 1.28, boiling point: 160° C.), and the like.

In the case of this embodiment, the volume of the liquid 38 is 50% or more and less than 100% of the volume of the space S, for example, about 75%. That is, in the space S, the liquid 38 is stored so as to occupy 50% or more of the volume of the space S, and the air 48 is stored in the remaining portion. The wavelength conversion device 30 is arranged such that the first surface 40a of the base body 40 is substantially parallel to the vertical direction. Therefore, when the wavelength conversion element 32 is stationary, the liquid 38 is in a state of being accumulated in the lower portion of the space S due to its own weight.

On the other hand, when the wavelength conversion element 32 is rotating, as shown in FIG. 4, the liquid 38 is pressed against the inner wall surface on the outer peripheral side of the base material body 40 in the space S by the centrifugal force. It becomes a state. That is, in the space S, the liquid 38 exists in the portion on the outer peripheral side of the wavelength conversion element 32, and the air 48 exists in the portion on the inner peripheral side of the wavelength conversion element 32. As described above, in the state in which the wavelength conversion element 32 is rotating, at least a part of the portion of the first surface 47a of the wavelength conversion unit 47 facing the liquid 38 becomes the incident region T of the excitation light E. Further, in the state where the temperature of the wavelength conversion unit 47 is increased by the irradiation of the excitation light E, the air 48 enclosed in the space S expands more than the liquid 38, so that the liquid 38 is pressed by the air 48 and the space It is stable when pressed against the inner wall surface of the outer peripheral side of S.

As described above, when the excitation light E enters the wavelength conversion unit 47, heat is generated in the incident region T of the excitation light E of the wavelength conversion unit 47, and then the heat propagates to the surroundings. At this time, if the joint portion is interposed between the wavelength conversion portion and the base material as in the wavelength conversion element of Patent Document 1, the joint portion is deteriorated by heat, and the reliability of the wavelength conversion element is lowered. There was a problem.

In response to this problem, according to the wavelength conversion element 32 of the present embodiment, the incident area T of the excitation light E faces the liquid 38, and the joint portion 37 is provided at a position outside the incident area T of the excitation light E. Therefore, deterioration of the joint portion 37 due to heat can be suppressed. Moreover, since the thermal conductivity generally increases in the order of gas→liquid→solid, the configuration of the present embodiment in which the space 38 is filled with the liquid 38 is wavelength conversion compared to the case where the space is filled with gas. The heat of the portion 47 is easily transferred to the base material 43, and the temperature rise of the wavelength conversion portion 47 is easily suppressed. This can suppress a decrease in wavelength conversion efficiency.

Further, in the case of a solid joint, even if the wavelength conversion element is rotated, the joint may locally deteriorate. On the other hand, in the wavelength conversion element 32 of the present embodiment, even if part of the liquid 38 is overheated, the heat is dispersed by convection of the liquid 38 in the space S, and the temperature of the liquid 38 is averaged. It is easy to be converted. Therefore, the degree of deterioration of the wavelength conversion unit 47 is averaged, and the speed of deterioration becomes slow. As described above, according to the present embodiment, it is possible to suppress the deterioration of the reliability of the wavelength conversion element 32.

Further, the wavelength conversion element 32 of the present embodiment is provided with the liquid 38 having a refractive index lower than that of the wavelength conversion portion 47 and lower than that of the bonding portion 37, whereby the following actions and effects are obtained. can get.

In the wavelength conversion element 32 of the present embodiment, the fluorescence Y isotropically radiated inside the wavelength conversion layer 42 travels inside the wavelength conversion layer 42 while scattering while hitting a scattering component such as a hole and scattering. Part of the fluorescent light Y reaches the first surface 47a of the wavelength conversion unit 47, and the other part of the fluorescent light Y reaches the second surface 47b of the wavelength conversion unit 47. The fluorescence Y that has reached the first surface 47a is a component excluding a component that is incident on the first surface 47a at a critical angle or more and is totally reflected, and a component that is incident on the first surface 47a and is Fresnel reflected at a critical angle or less. Passes through the first surface 42 a and is emitted from the wavelength conversion element 32. Further, the two reflection components described above travel inside the wavelength conversion unit 47 while scattering again and reach the first surface 47a or the second surface 47b.

On the other hand, of the fluorescence Y that has reached the second surface 47b, the light that is incident on the second surface 47b (the interface between the wavelength conversion unit 47 and the liquid 38) at an incident angle that is equal to or greater than the critical angle causes total loss and thus loss. The light travels inside the wavelength conversion unit 47 while being scattered again without being generated.

Further, of the fluorescence Y that has entered the second surface 47b (the interface between the wavelength conversion unit 47 and the liquid 38) at an incident angle less than the critical angle, the component that is not reflected by the wavelength conversion layer 42 and the dielectric multilayer film 39. Passes through the second surface 47b and is reflected by the reflective layer 41 of the base material 43. However, although the silver constituting the reflective layer 41 has a high light reflectance, it has a light absorptance of about 2%, so that the intensity of the fluorescence Y is attenuated each time the fluorescence Y enters the reflection layer 41. Of the fluorescence Y emitted inside the wavelength conversion layer 42, most of the components not emitted from the wavelength conversion element 32 correspond to the absorption components in the reflection layer 41. Therefore, it is important to reflect as much fluorescence Y as possible on the second surface 47b in order to prevent the fluorescence Y from entering the reflection layer 41 as much as possible and improve the light emission efficiency.

In addition, in this specification, the “luminous efficiency” is defined by the following equations (1) and (2).
Luminous efficiency = (amount of light emitted from wavelength conversion layer/amount of excitation light incident on wavelength conversion layer) (1)
Amount of light emitted from the wavelength conversion layer=amount of emitted light of fluorescence+amount of emitted unconverted excitation light (2)

The emission distribution of the fluorescence Y inside the wavelength conversion layer 42 is substantially isotropic in all directions. Therefore, the smaller the critical angle at the second surface 47b (the interface between the wavelength conversion section 47 and the liquid 38), the more the fluorescence Y reflected by the second surface 47b and the less the fluorescence Y incident on the reflective layer 41. be able to. Here, according to the wavelength conversion element 32 of the present embodiment, a liquid having a refractive index lower than the refractive index of the bonding portion 37 below the incident region T of the excitation light E corresponding to the main light emitting region of the wavelength conversion layer 42. Since 38 is present, the critical angle at the second surface 47b can be made smaller than that of a conventional wavelength conversion element in which a bonding layer is provided between the wavelength conversion section and the base material, for example. As a result, the wavelength conversion element 32 of the present embodiment can reduce the amount of the fluorescence Y incident on the reflective layer 41 and the loss of the fluorescence Y in the reflective layer 41 as compared with the conventional wavelength conversion element. Therefore, the luminous efficiency can be improved.

According to the calculation result of the present inventor, in the conventional wavelength conversion element, when the bonding layer made of the silicone resin having the refractive index of 1.41 is interposed between the wavelength conversion section and the base material, The critical angle on the two faces was 51.6°. In this case, of the fluorescence emitted from the wavelength conversion section, the proportion of the fluorescence that passed through the second surface of the wavelength conversion section and reached the reflective layer on the substrate was about 38%.

On the other hand, in the wavelength conversion element 32 of the present embodiment, when the liquid 38 made of perfluorocarbon having a refractive index of 1.28 is interposed between the wavelength conversion section 47 and the base material 43, The critical angle on the second surface 47b was 45.0°. In this case, of the fluorescence Y emitted from the wavelength conversion unit 47, the proportion of the fluorescence Y that has passed through the second surface 47b and reached the reflective layer 41 on the base material 43 was about 30%. As described above, according to the wavelength conversion element 32 of the present embodiment, the fluorescence Y lost in the reflective layer 41 can be reduced as compared with the conventional wavelength conversion element, and the light emission efficiency can be improved.

Further, in the wavelength conversion element 32 of the present embodiment, since the dielectric multilayer film 39 is provided on the second surface 42b of the wavelength conversion layer 42, the wavelength conversion unit 47 is incident on the second surface 47b at a critical angle or less. The amount of the fluorescent light Y reflected by the second surface 47b of the fluorescent light Y entering at an angle can be increased by the dielectric multilayer film 39. Thereby, the amount of the fluorescent light Y that reaches the reflecting surface 43r of the base material 43 can be reduced, and the loss on the reflecting surface 43r can be suppressed. As a result, the luminous efficiency of the wavelength conversion element 32 can be improved.

Further, in the wavelength conversion element 32 of the present embodiment, the liquid 38 occupies 50% or more of the volume of the space S. Therefore, when the wavelength conversion element 32 rotates, the liquid 38 moves to the outer peripheral side of the space S. Even in the pressed state, the liquid exists in at least a part of the portion facing the incident region T of the excitation light E. Further, if the liquid 38 occupies 50% or more of the volume of the space S, even if the wavelength conversion element 32 is stationary in the initial state, for example, the portion facing the incident region of the excitation light The liquid can be placed at least in part. Further, since the air 48 is present in a part of the space S in which the liquid 38 is stored, even if the substance contained in the liquid 38 is vaporized, the wavelength conversion portion 47 and the joint portion 37 are damaged. Can be suppressed.

The first lighting device 100 according to the first embodiment described above has the following effects.
Since the 1st illuminating device 100 of this embodiment is provided with the above-mentioned wavelength conversion element 32, the 1st illuminating device 100 in which loss in wavelength conversion element 32 was controlled can be realized.
In addition, in the first lighting device 100 of the present embodiment, the incident position of the excitation light E on the wavelength conversion layer 42 can be temporally moved by the motor 50 (rotating device), so that the temperature of the wavelength conversion layer 42 can be changed. The rise can be suppressed. Therefore, it is possible to provide the first lighting device 100 that can suppress a decrease in the emission efficiency of the wavelength conversion layer 42 and that has a small loss of the fluorescence Y.

The projector 1 according to the first embodiment described above has the following effects.
The projector 1 according to the present embodiment includes the above-described first lighting device 100, and thus can display a high-luminance image.

[Second Embodiment]
The second embodiment of the present invention will be described below with reference to FIG.
The configuration of the projector and the illumination device of the second embodiment is the same as that of the first embodiment, and the configuration of the wavelength conversion element is different from that of the first embodiment. Therefore, the description of the entire projector and the illumination device is omitted.
FIG. 5 is a sectional view of the wavelength conversion element of the second embodiment. This sectional view corresponds to the section taken along the line IV-IV in FIG. 3, as in FIG.
5, the same components as those in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, the wavelength conversion element 52 of the present embodiment includes a base material 43, a wavelength conversion section 47, a joint section 55, and a liquid 38.

The joint portion 55 has a resin portion 53 and a plurality of holding members 54 contained inside the resin portion 53. The resin portion 53 is made of, for example, a thermosetting silicone resin. The holding member 54 holds the space h between the reflective surface 43r and the second surface 42b. The holding member 54 is composed of spherical particles having a diameter of about 3 μm. Therefore, the interval h is also about 3 μm.

As a material of the holding member 54, for example, spherical particles made of silica are used. The plurality of holding members 54 are sandwiched between the wavelength conversion layer 42 and the base material 43 in a state where they are lined up in one layer without overlapping each other. The holding member 54 has rigidity such that the holding member 54 itself is not deformed while being sandwiched between the wavelength conversion layer 42 and the base material 43.
The other configurations of the wavelength conversion element 52 are similar to those of the wavelength conversion element 32 of the first embodiment.

Also in this embodiment, it is possible to suppress the deterioration of the reliability of the wavelength conversion element 52 by suppressing the deterioration of the joint portion 55 due to heat, and it is possible to increase the luminous efficiency of the wavelength conversion element 52, as in the first embodiment. The effect of is obtained.

Further, according to the wavelength conversion element 52 of the present embodiment, the distance between the reflection surface 43r and the second surface 47b, that is, the thickness h of the liquid 38 can be adjusted by the holding member 54. This makes it possible to optimize the thermal resistance between the wavelength conversion section 47 and the base material 43, and suppress a decrease in luminous efficiency.

[Third Embodiment]
Hereinafter, the third embodiment of the present invention will be described with reference to FIGS.
The schematic configuration of the projector of the third embodiment is similar to that of the first embodiment, and the configuration of the wavelength conversion device is different from that of the first embodiment. Therefore, the description of the entire projector is omitted.
FIG. 6 is a schematic configuration diagram of the projector 11 of the third embodiment. FIG. 7 is a front view of the wavelength conversion device 60. FIG. 8 is a cross-sectional view of the wavelength conversion device 60 taken along the line VIII-VIII of FIG.
6, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIG. 6, in the first lighting device 103 of the present embodiment, the wavelength conversion device 60 has a wavelength conversion element 62, and has a motor (rotation device) for rotating the wavelength conversion element 62. I haven't. Therefore, the excitation light E emitted from the first light source 10 enters the wavelength conversion element 62 in a stationary state.

As shown in FIGS. 7 and 8, the wavelength conversion element 62 of the present embodiment includes a base material 63, a wavelength conversion section 64, a bonding section 65, and a liquid 38. The wavelength conversion element 62 emits the fluorescence Y toward the same side as the side on which the excitation light E is incident. That is, the wavelength conversion element 62 is a reflective wavelength conversion element.

The base material 63 includes a base material body 66 and a reflective layer 67. Therefore, the base material 63 has the reflection surface 63r that reflects the fluorescence Y emitted from the wavelength conversion section 64. The base body 66 is made of a metal such as aluminum. The reflective layer 67 is composed of a metal film such as silver.

The wavelength conversion unit 64 has a wavelength conversion layer 68 and a dielectric multilayer film 69. The dielectric multilayer film 69 is provided on the surface of the wavelength conversion layer 68 that faces the reflection surface 63r. Further, the wavelength conversion unit 64 has a first surface 64a on which the excitation light E of the first wavelength band is incident and a second surface 64b opposite to the first surface 64a. The wavelength conversion layer 68 contains, for example, a YAG-based phosphor, and emits yellow fluorescence Y.

With the reflecting surface 63r and the second surface 64b separated from each other, the wavelength converting portion 64 and the base material 63 are joined together via the joining portion 65, so that the reflecting surface 63r, A space S surrounded by the two surfaces 64b and the joint portion 65 is formed. In the space S, a liquid 38 having optical transparency is stored. The joint portion 65 is made of a resin material such as silicone resin. The liquid 38 is made of a liquid such as perfluorocarbon having a refractive index lower than that of the wavelength conversion portion 64 and lower than that of the bonding portion 65.

The wavelength conversion element 62 is arranged such that the first surface 66a of the base body 66 is substantially parallel to the vertical direction. Therefore, when the wavelength conversion element 62 is stationary, the liquid 38 is in a state of being accumulated in the lower portion of the space S due to its own weight. In this state, at least a part of the portion of the first surface of the wavelength conversion unit 64 facing the liquid 38 is the incident region T of the excitation light E.
Other configurations of the projector 11 are similar to those of the first embodiment.

Also in the present embodiment, the deterioration of the reliability of the wavelength conversion element 62 can be suppressed by suppressing the deterioration of the joint portion 65 due to heat, and the light emission efficiency of the wavelength conversion element 62 can be increased, similar to the first embodiment. The effect of is obtained.

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 wavelength conversion element of the above-described embodiment, the liquid is contained in a part of the space surrounded by the reflection surface, the second surface, and the bonding portion, and the air is contained in the other part. The whole may be filled with liquid and no air may be present. In this case, the incident area of the excitation light on the first surface of the wavelength conversion section faces the liquid regardless of the orientation of the wavelength conversion element and the presence or absence of rotation.

Further, in the wavelength conversion element of the above embodiment, the dielectric multilayer film is provided on the second surface of the wavelength conversion layer, but the dielectric multilayer film may not necessarily be provided.

In addition, the specific description of the shape, the number, the arrangement, the material, and the like of each component of the wavelength conversion device, the illumination 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 has been shown, but the present invention is not limited to this. It may be mounted on a projector using a digital micromirror device as a light modulator.

In the above embodiment, an example in which the lighting device according to the present invention is mounted on a projector has been shown, but the present invention is not limited to this. The lighting device according to the present invention can be applied to lighting equipment, automobile headlights, and the like.

1, 11... Projector, 10... First light source (light source), 32, 52, 62... Wavelength conversion element, 35... Rotation axis, 37, 37E, 37I, 55, 65... Bonding part, 38... Liquid, 39... Dielectric Body multilayer film, 42... Wavelength conversion layer, 42b... Second surface (of wavelength conversion layer), 43, 63... Base material, 43r, 63r... Reflective surface, 47, 64... Wavelength conversion section, 47a, 64a... (Wavelength) First surface of conversion unit, 47b, 64b... Second surface of wavelength conversion unit, 50... Motor (rotating device), 100... First illumination device (illumination device), 400B, 400G, 400R... Light modulation device , 600... Projection optical device, E... Excitation light, Y... Fluorescence, S... Space, T... (Excitation light) incident area.

Claims (8)

A base material having a reflective surface,
A second surface having a first surface on which the excitation light of the first wavelength band is incident and a second surface opposite to the first surface, and the excitation light having a second surface different from the first wavelength band. A wavelength conversion unit that converts the wavelength into fluorescence in the wavelength band,
A joint portion that joins the wavelength conversion portion and the base material,
A liquid contained in a space surrounded by the reflective surface, the second surface, and the joint, the reflective surface and the second surface being separated from each other;
Equipped with
A wavelength conversion element, wherein at least a part of a portion of the first surface facing the liquid is an incident region of the excitation light. The wavelength conversion element according to claim 1, wherein the wavelength conversion unit includes a wavelength conversion layer and a dielectric multilayer film provided on a surface of the wavelength conversion layer that faces the reflection surface. The wavelength conversion element according to claim 1 or 2, wherein a refractive index of the liquid is lower than a refractive index of the wavelength conversion unit. The wavelength conversion element according to claim 3, wherein the liquid has a refractive index lower than that of the bonding portion. The wavelength conversion element according to any one of claims 1 to 4, wherein the volume of the liquid is 50% or more of the volume of the space. A wavelength conversion element according to any one of claims 1 to 5,
A lighting device, comprising: a light source that emits the excitation light toward the wavelength conversion element. The wavelength conversion element is rotatable about a rotation axis,
The illumination device according to claim 6, further comprising a rotation device that rotates the wavelength conversion element around the rotation axis. A lighting device according to claim 6 or 7,
A light modulation device that modulates light from the lighting device according to image information,
A projection optical device that projects the light modulated by the light modulation device.

Images