CN113934095B

CN113934095B - Wavelength conversion device, projector, and phosphor ceramic member

Info

Publication number: CN113934095B
Application number: CN202110701893.2A
Authority: CN
Inventors: 阿部岳志; 本多洋介
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2020-06-29
Filing date: 2021-06-24
Publication date: 2024-01-23
Anticipated expiration: 2041-06-24
Also published as: DE102021116016A1; CN113934095A; TW202201108A; TW202238245A; TWI802918B

Abstract

The invention provides a wavelength conversion device, a projector, and a phosphor ceramic member, which have high light utilization efficiency. A wavelength conversion device (1) for a projector (100) emits reflected light (L2) including fluorescence upon receiving stimulated luminescence (L1), wherein the wavelength conversion device comprises a substrate (10) having a light reflection surface (13) and a phosphor ceramic layer (20) which is positioned above the light reflection surface (13) and includes a first crystal phase having a garnet structure, the visible light reflectance of the light reflection surface (13) is 95-100%, the density of the phosphor ceramic layer (20) is 97-100% of the theoretical density, and the film thickness of the phosphor ceramic layer (20) is 50 [ mu ] m or more and less than 120 [ mu ] m.

Description

Wavelength conversion device, projector, and phosphor ceramic member

Technical Field

The present invention relates to a wavelength conversion device, a projector using the same, and a phosphor ceramic member.

Background

Conventionally, a wavelength conversion device for a projector is known.

For example, patent document 1 discloses a wavelength conversion device that includes a substrate having a circular shape in a plan view and a phosphor layer (phosphor ceramic member) provided along a circumferential direction of the substrate, and is rotatable by a motor connected to a center of the substrate. In patent document 1, the wavelength conversion device functions as a reflective phosphor wheel in a projector, and fluorescence emitted from a phosphor layer of the wavelength conversion device is used as light (projection light) emitted from the projector.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open publication No. 2019-66880

Disclosure of Invention

Problems to be solved by the invention

However, the conventional wavelength conversion device, projector, and phosphor ceramic member have a problem of low light utilization efficiency. Accordingly, the present invention provides a wavelength conversion device, a projector, and a phosphor ceramic member, each of which has high light utilization efficiency.

Means for solving the problems

The wavelength conversion device according to one embodiment of the present invention is used in a projector, emits reflected light including fluorescence upon receiving stimulated luminescence, and includes a substrate having a light reflection surface and a phosphor ceramic layer, wherein the phosphor ceramic layer is located above the light reflection surface and includes a first crystal phase having a garnet structure, the visible light reflectance of the light reflection surface is 95% to 100%, the density of the phosphor ceramic layer is 97% to 100% of the theoretical density, and the film thickness of the phosphor ceramic layer is 50 [ mu ] m or more and less than 120 [ mu ] m.

A projector according to an embodiment of the present invention includes an excitation light source that emits excitation light, and the wavelength conversion device that receives the excitation light and emits reflected light including fluorescence.

The phosphor ceramic member according to one embodiment of the present invention is a phosphor ceramic member for a projector, comprising a first crystal phase having a garnet structure and a second crystal phase having a structure other than the garnet structure, wherein the density of the phosphor ceramic member is 97% to 100% of the theoretical density, and the film thickness of the phosphor ceramic member is 50 μm or more and less than 300 μm.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a wavelength conversion device, a projector, and a phosphor ceramic member, each of which has high light utilization efficiency, can be provided.

Drawings

Fig. 1 is a perspective view of a wavelength conversion device of an embodiment.

Fig. 2 is a cross-sectional view showing a cut-out surface of the wavelength conversion device at line II-II of fig. 1.

Fig. 3 is a perspective view showing an external appearance of the projector according to the embodiment.

Fig. 4 is a schematic diagram showing an optical system of the projector according to the embodiment.

Fig. 5A is a schematic diagram showing a wavelength conversion device and an aperture member according to an embodiment.

Fig. 5B is a schematic diagram showing a wavelength conversion device and an aperture member of a comparative example of the embodiment.

Fig. 6 is a graph showing evaluation results of the wavelength conversion devices of the examples and the comparative examples of the embodiment.

Fig. 7 is a graph showing the evaluation result of the wavelength conversion device according to the example of the embodiment.

Fig. 8 is a perspective view of the wavelength conversion device of modification 1.

Fig. 9 is a cross-sectional view showing a cut-out surface of the wavelength conversion device at line IX-IX of fig. 8.

Fig. 10 is an SEM image showing a cross section of a phosphor ceramic layer according to the embodiment of modification 1.

Fig. 11 is a graph showing the evaluation result of the wavelength conversion device according to the embodiment of modification 1.

Fig. 12 is a perspective view of a phosphor ceramic member according to modification 2.

Symbol description

1. Wavelength conversion device

10. Substrate board

11. Substrate main body

12. Light reflecting layer

13. Light reflecting surface

20. Phosphor ceramic layer

30. Anti-reflection layer

100. Projector with a light source for projecting light

121. Light scattering particles

L1 excitation light

L2 reflected light

Detailed Description

Hereinafter, a wavelength conversion device and the like according to an embodiment of the present invention will be described in detail with reference to the drawings.

The embodiments described below each represent a general or specific example. The numerical values, shapes, materials, components, arrangement positions and connection modes of the components, manufacturing processes, order of the manufacturing processes, and the like shown in the following embodiments are examples, and do not limit the gist of the present invention. Among the constituent elements in the following embodiments, constituent elements not described in the independent claims are described as optional constituent elements.

The drawings are schematic and are not strictly illustrated. Therefore, for example, the scales and the like in the drawings are not necessarily uniform. In the drawings, substantially the same components are denoted by the same reference numerals, and repetitive description thereof will be omitted or simplified.

In the present specification, terms indicating a relationship between elements such as parallel and orthogonal, terms indicating a shape of elements such as circular and elliptical, and numerical ranges are not only expressions in strict meaning, but also expressions including substantially equivalent ranges, for example, differences of about several%.

In the present specification, "planar view" refers to a case where the wavelength conversion device is viewed in a direction perpendicular to a light reflection surface of the substrate.

In the present specification, terms such as "upper" and "lower" in the configuration of the wavelength conversion device do not refer to upper (vertically upper) and lower (vertically lower) in absolute spatial recognition, but are terms defined according to a relative positional relationship based on a lamination order in the laminated structure. The terms "upper" and "lower" are applied not only to a case where two components are arranged with a gap therebetween and other components are present between the two components, but also to a case where the two components are arranged so as to be in close contact with each other.

In the present specification and the drawings, the x-axis, the y-axis, and the z-axis represent three axes of a three-dimensional orthogonal coordinate system. In each embodiment, the x-axis and the y-axis are two axes parallel to the light reflection surface of the substrate, and the z-axis is a direction perpendicular to the light reflection surface. In the embodiments described below, the positive z-axis direction may be referred to as the upper direction, and the negative z-axis direction may be referred to as the lower direction.

(embodiment)

[ construction of wavelength conversion device ]

First, the configuration of the wavelength conversion device 1 according to the present embodiment will be described with reference to the drawings. Fig. 1 is a perspective view of a wavelength conversion device 1 of the present embodiment. Fig. 2 is a cross-sectional view showing a cut surface of the wavelength conversion device 1 at line II-II of fig. 1.

As shown in fig. 1 and 2, the wavelength conversion device 1 includes a substrate 10 having a light reflection surface 13, a phosphor ceramic layer 20, and an antireflection layer 30.

In the present embodiment, the wavelength conversion device 1 is a phosphor wheel for a projector that receives the excitation light L1 and emits reflected light including fluorescence. The wavelength conversion device 1 has a disk shape, and a motor 4 for rotationally driving is provided at the center of the wavelength conversion device 1 in a plan view. Accordingly, the wavelength conversion device 1 rotationally drives the motor 4 by the motor 4 in the direction of the arrow shown in fig. 1 in the axial direction.

In addition, although fig. 1 shows the structure of the phosphor wheel provided with the motor 4, the wavelength conversion device 1 may not be provided with the motor 4. That is, the wavelength conversion device 1 may be a fixed device that does not perform rotational driving. With such a configuration, the wavelength conversion device 1 becomes small, and thus a compact projector can be provided.

The phosphor ceramic layer 20 is a layer located above the light reflection surface 13 provided on the substrate 10. In the present embodiment, the wavelength conversion device 1 is a phosphor wheel, and therefore the phosphor ceramic layer 20 is a phosphor ring. The phosphor ceramic layer 20 is provided on a circumference equal to the distance from the rotation center portion of the wavelength conversion device 1 (i.e., the position where the motor 4 is provided) in an annular shape. That is, the phosphor ceramic layer 20 is provided in a band shape in the circumferential direction in a plan view.

The phosphor ceramic layer 20 includes a first crystal phase having a garnet structure. More specifically, in the present embodiment, the phosphor ceramic layer 20 is composed of only the first crystal phase having a garnet structure. That is, the phosphor ceramic layer 20 of the present embodiment does not contain a crystal phase having a structure different from the garnet structure. Garnet structure is defined by A ₃ B ₂ C ₃ O ₁₂ A crystal structure represented by the general formula (I). For element a, rare earth elements such as Ca, Y, la, ce, pr, nd, sm, eu, gd, tb and Lu are applicable; as the element B, mg, al, si, ga, sc, and other elements are applicable; as the element C, elements such as Al, si, and Ga are suitable. Examples of such garnet structures include: YAG (yttrium-aluminum-garnet (Yttrium Aluminum Garnet)) LuAG (lutetium-aluminum-garnet (Lutetium Aluminum Garnet)), lu ₂ CaMg ₂ Si ₃ O ₁₂ (lutetium-calcium-magnesium-silicon-garnet (Lutetium Calcium Magnesium Silicon Garnet)) and TAG (terbium-aluminum-garnet (Terbium Aluminum Garnet)) and the like. In the present embodiment, the phosphor ceramic layer 20 is formed of a material consisting of (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ (i.e. (Y) _1-x Ce _x ) ₃ Al ₅ O ₁₂ ) The first crystal phase is YAG, x is more than or equal to 0.001 and less than 0.1.

Further, the first crystal phase constituting the phosphor ceramic layer 20 may be a solid solution of a plurality of garnet crystal phases having different chemical compositions. Examples of such solid solutions include those composed of (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ Guava Dan Jingxiang expressed by (Lu _1- _d Ce _d ) ₃ Al ₂ Al ₃ O ₁₂ (0.001.ltoreq.d < 0.1) solid solution ((1-a) (Y) of pomegranate Dan Jingxiang _1-x Ce _x ) ₃ Al ₅ O ₁₂ -a(Lu _1-d Ce _d ) ₃ Al ₂ Al ₃ O ₁₂ (0 < a < 1)) (0.001. Ltoreq.x < 0.1). Further, as such solid solution, there may be mentioned a solid solution formed of (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ Guava Dan Jingxiang expressed by (Lu _1-z Ce _z ) ₂ CaMg ₂ Si ₃ O ₁₂ The solid solution ((1-b) (Y) of pomegranate Dan Jingxiang is represented _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ -b(Lu _1-z Ce _z ) ₂ CaMg ₂ Si ₃ O ₁₂ (0 < b < 1)), (0.001 < x < 0.1), (0.0015 < z < 0.15), and the like. By making the phosphor ceramic layer 20 of a solid solution of a plurality of garnet crystal phases having different chemical compositions, the fluorescence spectrum of the fluorescence emitted from the phosphor ceramic layer 20 is widened, and the green light component and the red light component are increased. Therefore, a projector that emits projection light having a wide color gamut can be provided.

In addition, the phosphor ceramic is formedThe first crystalline phase of the porcelain layer 20 may also comprise a chemical composition represented by formula A as described above ₃ B ₂ C ₃ O ₁₂ The indicated phase deviates from the crystalline phase. Such a crystal phase may be a phase of (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ Expressed as Al-rich crystalline phase (Y _1-x Ce _x ) ₃ Al _2+δ Al ₃ O ₁₂ (0.001 is less than or equal to x is less than 0.1) (delta is a positive number). Further, as such a crystal phase, there can be mentioned a crystal phase (a) relative to the crystal phase (Y _1-x Ce _x ) ₃ Al ₂ Al ₃ O ₁₂ The indicated crystal phase is rich in Y (Y _1-x Ce _x ) _3+ζ Al ₂ Al ₃ O ₁₂ (x is more than or equal to 0.001 and less than 0.1) (zeta is a positive number) and the like. The chemical composition of these crystalline phases is relative to that represented by the general formula A ₃ B ₂ C ₃ O ₁₂ The indicated phase deviates but the garnet structure is maintained. Since the phosphor ceramic layer 20 is composed of a crystal phase having a chemical composition that is deviated, a region having a different refractive index is generated in the phosphor ceramic layer 20, and thus the excitation light L1 and the fluorescence are further scattered, and the light emitting area of the phosphor ceramic layer 20 is reduced. Therefore, the wavelength conversion device 1 and the projector having a smaller etendue and a higher light utilization efficiency can be provided.

Further, the phosphor ceramic layer 20 may contain a first crystal phase and a hetero-phase having a structure other than the garnet structure. Since the phosphor ceramic layer 20 is composed of such a first crystal phase and a heterogeneous phase, regions having different refractive indexes are generated in the phosphor ceramic layer 20, and thus the excitation light L1 and the fluorescence are further scattered, and the light emitting area of the phosphor ceramic layer 20 becomes smaller. Therefore, the wavelength conversion device 1 and the projector having a smaller etendue and a higher light utilization efficiency can be provided.

The phosphor ceramic layer 20 made of YAG receives light incident from above the wavelength conversion device 1 and emits fluorescence as excitation light L1. More specifically, by irradiating the phosphor ceramic layer 20 with light emitted from an excitation light source described later as excitation light L1, fluorescence is emitted from the phosphor ceramic layer 20 as wavelength-converted light. That is, the wavelength-converted light emitted from the phosphor ceramic layer 20 is light having a longer wavelength than the excitation light L1.

In the present embodiment, the wavelength-converted light emitted from the phosphor ceramic layer 20 includes fluorescence that is yellow light. The phosphor ceramic layer 20 absorbs light having a wavelength of 380nm to 490nm, for example, and emits fluorescence as yellow light having a fluorescence peak wavelength in a region having a wavelength of 490nm to 580 nm. By configuring the phosphor ceramic layer 20 from YAG, it is possible to easily realize the phosphor ceramic layer 20 that emits fluorescence having a fluorescence peak wavelength in a region having a wavelength of 490nm to 580 nm.

The x-coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20 may be 0.415 or less, more preferably 0.410 or less, and still more preferably 0.408 or less. If the x-coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20 is the above-described value, the temperature quenching of the phosphor ceramic layer 20 becomes small, and thus the phosphor ceramic layer 20 having high luminous efficiency can be realized.

The density of the phosphor ceramic layer 20 may be 95% to 100% of the theoretical density, and more preferably 97% to 100% of the theoretical density. Here, the theoretical density refers to a density in the case where atoms in the layer are set to be desirably aligned. In other words, the theoretical density refers to a density assuming that there is no void in the phosphor ceramic layer 20, which is a value calculated using a crystal structure. For example, when the density of the phosphor ceramic layer 20 is 99%, the remaining 1% corresponds to a void. That is, the higher the density of the phosphor ceramic layer 20, the fewer the voids. If the density of the phosphor ceramic layer 20 is in the above range, the total amount of fluorescence emitted from the phosphor ceramic layer 20 increases, and therefore the wavelength conversion device 1 and the projector with a larger amount of emitted light can be provided.

In addition, the density of the phosphor ceramic layer 20 may be 4.32g/cm ³ ～4.55g/cm ³ More preferably 4.41g/cm ³ ～4.55g/cm ³ . As shown in the present embodiment, in the case where the phosphor ceramic layer 20 is made of YAG, if the density of the phosphor ceramic layer 20 is in the above range, the density of the phosphor ceramic layer 20 becomes 9 of the theoretical density of each5 to 100 percent and 97 to 100 percent. By setting the density of the phosphor ceramic layer 20 to the above range, the excitation light L1 absorbed by the phosphor ceramic layer 20 can be efficiently converted into fluorescence. That is, the phosphor ceramic layer 20 having high luminous efficiency can be realized.

The thickness (length in the z-axis direction) of the phosphor ceramic layer 20 is preferably 50 μm or more and less than 150 μm, more preferably 50 μm or more and less than 120 μm. The thickness of the phosphor ceramic layer is more preferably 70 μm or more and less than 120 μm, still more preferably 80 μm or more and less than 110 μm.

Further, the anti-reflection layer 30 is located above the phosphor ceramic layer 20.

The antireflection layer 30 is a layer that prevents, more specifically, the reflection of the excitation light L1 from being suppressed. The anti-reflection layer 30 reduces the reflectance of the excitation light L1 in the wavelength conversion device 1 and increases the amount of the excitation light L1 reaching the phosphor ceramic layer 20. As a result, the amount of excitation light L1 that can be absorbed by the phosphor ceramic layer 20 also increases, and therefore the amount of fluorescence emitted by the phosphor ceramic layer 20 also increases. That is, by providing the antireflection layer 30, the amount of fluorescence emitted from the phosphor ceramic layer 20 increases.

The antireflection layer 30 may be formed of, for example, a dielectric film or a periodic fine uneven structure (so-called moth-eye structure) having a wavelength smaller than that of light in the visible light region. In the case where the antireflection layer 30 is made of a dielectric film, the antireflection layer 30 may contain an inorganic compound. In this case, the anti-reflection layer 30 contains a material selected from SiO ₂ 、TiO ₂ 、Al ₂ O ₃ 、ZnO、Nb ₂ O ₅ And MgF, etc.

Although fig. 1 and 2 show the configuration in which the antireflection layer 30 is provided, the wavelength conversion device 1 may not include the antireflection layer 30.

The substrate 10 is a plate material having a disk shape, and is a base material for supporting the phosphor ceramic layer 20 and the antireflection layer 30. The motor 4 is provided in the center of the substrate 10 in a plan view. As shown in fig. 2, the substrate 10 has a substrate body 11 and a light reflecting layer 12.

The substrate body 11 may be composed of a material having high thermal conductivity. For example, the substrate body 11 may be composed of a material having higher thermal conductivity than the phosphor ceramic layer 20, but is not limited thereto. The substrate body 11 may be exemplified by: glass substrates, quartz substrates, gaN substrates, sapphire substrates, si substrates, metal substrates, and the like. The substrate body 11 may be made of a resin such as a PEN (polyethylene naphthalate) film or a PET (polyethylene terephthalate) film. Further, when the substrate body 11 is a metal substrate, the substrate body 11 is made of a metal material such as Al, fe, or Ti.

In the present embodiment, the substrate body 11 is a metal substrate made of Al. Al has high thermal conductivity and is lightweight, and thus can improve the heat release of the substrate body 11 and reduce the weight of the substrate body 11. The thickness of the substrate body 11 is, for example, 1.5mm or less.

The substrate 10 has a light reflection surface 13. The light reflection surface 13 is a surface of the substrate 10 on the side of the phosphor ceramic layer 20. In the present embodiment, the light reflection surface 13 is constituted by a surface included in the light reflection layer 12.

The light reflection surface 13 is a surface that reflects fluorescence emitted from the phosphor ceramic layer 20. The light reflection surface 13 also reflects the excitation light L1 not converted into fluorescence in the phosphor ceramic layer 20. The light reflection surface 13 reflects the fluorescence and excitation light L1 not converted into fluorescence upward. In the present embodiment, since the fluorescence and excitation light L1 is light in the visible light range, the higher the visible light reflectance of the light reflection surface 13 is, the less the light loss is. Specifically, the visible light reflectance of the light reflection surface 13 may be 90% to 100%, and more preferably 95% to 100%. If the visible light reflectance of the light reflection surface 13 is in the above range, the fluorescence and excitation light L1 is reflected further upward, and therefore guided waves of the fluorescence and excitation light L1 in the lateral direction (i.e., the direction parallel to the light reflection surface 13) can be suppressed, and the light emission area becomes smaller. Therefore, the wavelength conversion device 1 and the projector having a smaller etendue and a higher light utilization efficiency can be provided. The reflectance of light in the wavelength region of 490nm to 780nm of the light reflection surface 13 may be 90% to 100%, and more preferably 95% to 100%. If the reflectance of light in the wavelength region of 490nm to 780nm of the light reflection surface 13 is in the above range, fluorescence can be reflected further upward, and therefore guided waves of fluorescence in the lateral direction can be suppressed, and the light emission area can be made smaller. Therefore, the wavelength conversion device 1 and the projector having a smaller etendue and a higher light utilization efficiency can be provided. In the present embodiment, the visible light range refers to a wavelength range of 380nm to 780 nm.

The light reflection layer 12 is made of any material as long as it can reflect the fluorescence and excitation light L1 that is not converted into fluorescence upward. In the present embodiment, the light reflection layer 12 is a composite layer composed of light scattering particles 121 and a binder 122 in which the light scattering particles 121 are dispersed. That is, the light reflection layer 12 has light diffusibility (light scattering property), and reflects fluorescence and excitation light L1 that is not converted into fluorescence upward by light diffusion.

The light reflection layer 12 diffuses light by a refractive index difference between the light scattering particles 121 and the binder 122. The light scattering particles 121 are, for example, fillers or white particles composed of an inorganic compound or a resin material. More specifically, the light scattering particles 121 may be SiO ₂ 、TiO ₂ 、Al ₂ O ₃ 、ZnO、Nb ₂ O ₅ 、ZrO ₂ CaCO (CaCO) ₃ The inorganic compound may be a resin material such as a styrene resin or an acrylic resin. The adhesive 122 may be made of a resin material such as an acrylic resin and a silicone resin having light transmittance.

By providing the light reflection layer 12, the visible light reflectance of the light reflection surface 13 can be improved. Further, the light reflection layer 12 is made of a composite layer including the light scattering particles 121, whereby the visible light reflectance of the light reflection surface 13 can be further improved. That is, the loss of light in the wavelength conversion device 1 can be further suppressed.

Further, the light reflection layer 12 may be a metal layer composed of a metal having light reflectivity. For example, the metal is an alloy containing Ag, al, or any one of them. As for the light reflection layer 12, it may be formed by performing a dry process or a wet process on the metal. Even in such a case, the same operational effects as those in the case where the light reflection layer 12 is constituted of the composite layer containing the light scattering particles 121 are expected.

In addition, a bonding layer may be provided between the light reflection layer 12 and the phosphor ceramic layer 20. By setting the configuration as described above, the light reflection layer 12 and the phosphor ceramic layer 20 are further in close contact with each other, and therefore, heat generated in the phosphor ceramic layer 20 can be efficiently conducted to the substrate main body 11 via the light reflection layer 12. Therefore, the wavelength conversion device 1 having less temperature quenching of the phosphor ceramic layer 20 can be provided with high efficiency. The bonding layer may be formed of a transparent material such as a silicone resin or an epoxy resin. The thickness of the bonding layer may be 1 μm or more and less than 100 μm, and preferably 1 μm or more and less than 20 μm.

Although fig. 1 and 2 show the configuration in which the light reflection layer 12 is provided, the wavelength conversion device 1 may not include the light reflection layer 12. In this case, the surface of the substrate body 11 serves as the light reflection surface 13.

[ construction of projector ]

The wavelength conversion device 1 configured as described above is used for the projector 100 shown in fig. 3 and 4. Fig. 3 is a perspective view showing an external appearance of the projector 100 according to the present embodiment. Fig. 4 is a schematic diagram showing an optical system of the projector 100 according to the present embodiment. The configuration of projector 100 according to the present embodiment will be described below with reference to fig. 3 and 4.

As shown in fig. 3 and 4, the projector 100 of the present embodiment includes a light source 3, a dichroic mirror 5, a wavelength conversion device 1, a display element 6, a projection optical member 7, and a reflecting mirror 8.

The light source 3 is, for example, a semiconductor laser light source or a LED (Light Emitting Diode) light source, and is driven by a driving current to emit light of a predetermined color (wavelength).

In the present embodiment, the light source 3 is a semiconductor laser light source. The semiconductor laser element included in the light source 3 is, for example, a GaN-based semiconductor laser element (laser chip) made of a nitride semiconductor material. In the present embodiment, the light source 3 as a semiconductor laser light source is a multi-chip type light emitting device.

As an example, the light source 3 emits laser light in a range from near ultraviolet to blue having a peak wavelength of 380nm to 490 nm. More specifically, the light source 3 emits blue light having a peak wavelength of 445 nm. The light source 3 of the present embodiment is an example of an excitation light source. The laser light emitted from the light source 3 reaches the dichroic mirror 5.

The dichroic mirror 5 is disposed at an angle of 45 degrees with respect to the optical axis of the light source 3. The dichroic mirror 5 of the present embodiment is a dichroic mirror that transmits a part of blue light, reflects the other part, and transmits yellow-based fluorescence.

That is, the dichroic mirror 5 has a characteristic of reflecting and transmitting light in a wavelength region of the laser light emitted from the light source 3. Therefore, a part of the laser light emitted from the light source 3 is transmitted through the dichroic mirror 5 without changing its traveling direction, and the other part of the laser light is reflected by the dichroic mirror 5, and the traveling direction is changed by 90 ° toward the wavelength conversion device 1.

Here, the other part of the laser light emitted from the light source 3 reaches the wavelength conversion device 1 as excitation light L1. The wavelength conversion device 1 emits reflected light L2 including fluorescence upon receiving the excited light L1. More specifically, the reflected light L2 includes light that has been wavelength-converted and reflected by the phosphor ceramic layer 20 and the light reflection surface 13 provided in the wavelength conversion device 1, respectively. More specifically, the reflected light L2 is light including yellow-based fluorescence generated in the phosphor ceramic layer 20 and excitation light L1, which is blue light that is not converted into fluorescence in the phosphor ceramic layer 20. However, since the proportion of fluorescence in the reflected light L2 is high, the reflected light L2 is yellow light.

The laser light transmitted from the dichroic mirror 5 without changing the traveling direction reaches the reflecting mirror 8 as the transmission light L12, and is specularly reflected by the reflecting mirror 8 toward the other surface of the dichroic mirror 5. The transmitted light L12 is reflected by the other surface of the dichroic mirror 5, and the traveling direction is changed by 90 ° to be directed to the display element 6.

In addition, the reflected light L2 reaches the dichroic mirror 5. At this time, the dichroic mirror 5 is disposed at an angle of 45 degrees with respect to the optical axis of the reflected light L2, and transmits yellow-based fluorescence. Therefore, the traveling direction of the reflected light L2 that has reached the dichroic mirror 5 does not change.

As a result, as shown in fig. 4, the optical axis of the reflected light L2 is oriented toward the display element 6 in agreement with the optical axis of the transmitted light L12. At this time, the reflected light L2 is yellow light, and the transmitted light L12 is blue light, so that the light obtained by combining these lights is white light. That is, the light from the dichroic mirror 5 toward the display element 6 is white light.

The white light, which is the mixed light of the reflected light L2 and the transmitted light L12, is directed toward the display element 6. Here, if the reflected light L2 is light having a large etendue, the size of the reflected light L2 irradiated to the display element 6 becomes larger than the size of the display element 6. Therefore, an ineffective (i.e., unusable) light component not irradiated to the display element 6 becomes large.

The display element 6 is a substantially planar element that controls and outputs light (white light) passing through the opening 2a in the form of an image. In other words, the display element 6 generates light for imaging. The display element 6 is in particular a DLP (digital light processor; digital Light Processing) with a DMD (digital micromirror device; digital Micromirror Device). The display element 6 may be, for example, a reflective liquid crystal panel. Further, a fly-eye lens, a polarization conversion element, a mirror rod, and the like may be provided between the display element 6 and the dichroic mirror 5.

The light for image generated by the display element 6 is projected by the projection optical member 7 to be projected light for enlarging the screen.

In the projector 100, only the light irradiated to the display element 6 is used as the projection light. That is, the smaller the etendue of the reflected light L2, the more light that can be used as projection light of the projector 100.

[ optical behavior in wavelength conversion device ]

Here, the optical behavior in the wavelength conversion device 1 will be described with reference to this embodiment and comparative example.

Fig. 5A is a schematic diagram showing the wavelength conversion device 1 and the diaphragm member 2 according to the present embodiment. Fig. 5B is a schematic diagram showing a wavelength conversion device 1x and an aperture member 2 of a comparative example of the present embodiment. For convenience, the description will be made here with reference to the ring member 2, the wavelength conversion devices 1 and 1x, the excitation light L1, and the reflected light L2.

Here, the diaphragm member 2 is a member for evaluating the magnitude of the etendue of the reflected light L2. The aperture member 2 absorbs light and an opening 2a is provided in a central portion of the aperture member 2. It is considered that if the proportion of the light component passing through the aperture 2a of the diaphragm member 2 is relatively large, the etendue of the reflected light L2 is small.

The wavelength conversion device 1x of the comparative example has the same configuration as the wavelength conversion device 1 of the present embodiment except that the thickness of the phosphor ceramic layer 20x is thicker (for example, 200 μm) than the phosphor ceramic layer 20 of the present embodiment.

The density of the phosphor ceramic layer 20 and 20x was 4.41g/cm ³ ～4.55g/cm ³ The density is high. That is, since the phosphor ceramic layers 20 and 20x have few voids and are less likely to scatter light, light tends to advance in the planar view direction (i.e., the x-axis direction or the y-axis direction) of the layers, and so-called light guiding tends to occur.

First, the wavelength conversion device 1 of the present embodiment will be described with reference to fig. 5A.

If the thickness is sufficiently small (50 μm to 120 μm) as in the phosphor ceramic layer 20 of the present embodiment, the distance D in the planar view direction (in this case, the x-axis direction) of the layer from the incidence of the excitation light L1 to the emission of the reflected light L2 can be further shortened. In other words, in the present embodiment, the light emitting area (light emitting spot diameter) of fluorescence of the phosphor ceramic layer 20 is sufficiently small. Therefore, as shown in fig. 5A, the reflected light L2 reflected by the light reflection surface 13 and emitted from the phosphor ceramic layer 20 easily passes through the aperture 2a of the diaphragm member 2. As described above, the light passing through the opening 2a can be used as light for enlarging projection onto the screen via the display element 6 and the projection optical member 7.

That is, in the present embodiment, the thickness of the phosphor ceramic layer 20 included in the wavelength conversion device 1 is sufficiently small, and therefore the light emitting area of fluorescence can be sufficiently reduced. Therefore, the light passing through the aperture 2a of the diaphragm member 2 is large, and the light that can be used as projection light of the projector 100 is large. That is, with the above configuration, the wavelength conversion device 1 having high light utilization efficiency can be realized. Further, by providing such a wavelength conversion device 1, a projector 100 having high light utilization efficiency can be realized.

Next, a wavelength conversion device 1x of a comparative example will be described with reference to fig. 5B.

If the thickness is sufficiently thick (200 μm) as in the phosphor ceramic layer 20x of the comparative example, the distance Dx in the planar view of the layer from the incidence of the excitation light L1 to the incidence of the reflection light L2x becomes longer. In other words, in the comparative example, the light emitting area (light emitting spot diameter) of fluorescence of the phosphor ceramic layer 20x becomes large. Therefore, as shown in fig. 5B, the reflected light L2x reflected by the light reflection surface 13 and emitted from the phosphor ceramic layer 20x is easily blocked by the diaphragm member 2. Therefore, the wavelength conversion device 1x of the comparative example has low light utilization efficiency.

As described above, in the present embodiment, by providing the light reflection layer 12 and further by forming the light reflection layer 12 from a composite layer including the light scattering particles 121, the visible light reflectance of the light reflection surface 13 can be further improved. This can further suppress the loss of light in the wavelength conversion device 1, and thus can realize the wavelength conversion device 1 having high light utilization efficiency.

Examples

Here, in the wavelength conversion devices of examples 1 to 3 and comparative examples of the present embodiment, a manufacturing method and light use efficiency will be described.

First, a method for producing a phosphor ceramic layer is described.

The phosphor ceramic layers of examples 1 to 3 and comparative example were each composed of a phosphor layer of (Y _0.9953 Ce _0.0047 ) ₃ Al ₅ O ₁₂ The first crystalline phase is shown. The phosphor ceramic layers of examples 1 to 3 and comparative example are each composed of Ce ³⁺ And activating the fluorescent body.

The phosphor ceramic layers of examples 1 to 3 and comparative examples used the following three compound powders as raw materials. Specifically, Y is used ₂ O ₃ (yttria, purity 3N, nippon Yttrium Co., ltd.) Al ₂ O ₃ (alumina, 3N purity, sumitomo chemical Co., ltd.) and CeO ₂ (cerium oxide, purity 3N, day)The instant yttrium corporation).

First, the compound (Y) is formed into a stoichiometric composition _0.9953 Ce _0.0047 ) ₃ Al ₅ O ₁₂ The above raw materials were weighed. Next, the weighed raw materials and alumina balls (diameter: 10 mm) were put into a plastic pot. The amount of the alumina balls is about 1/3 of the volume of the plastic can. Thereafter, pure water was poured into a plastic pot, and the raw material was mixed with pure water by a pot rotating device (BALL MILL ANZ-51S, manufactured by Nissan chemical Co., ltd.). The mixing was performed for 12 hours. Thus, a slurry-like mixed raw material was obtained.

The slurry-like mixed raw material was dried using a dryer. Specifically, a piece of Naflon (registered trademark) was laid so as to cover the inner wall of the metal tub, and the mixed raw material was flowed over the piece of Naflon (registered trademark). In the case of a metal drum, a Naflon (registered trademark) sheet and a mixed raw material, they were treated with a dryer set at 150℃for 8 hours and dried. Thereafter, the dried mixed raw material is recovered, and the mixed raw material is granulated by a spray-drying apparatus. In addition, polyvinyl alcohol is used as a binder (binder) in granulation.

The granulated mixed raw material was molded into a cylinder by an electric hydraulic press (EMP-5, manufactured by Lithospermum Co., ltd.) and a cylinder mold (outer diameter: 58mm, inner diameter: 38mm, height: 130 mm). The pressure during molding was set to 5MPa/cm ² . Next, the molded article after the temporary molding was subjected to main molding by a cold isostatic pressing device. The pressure at the time of main molding was set to 300MPa. The molded article after the main molding is subjected to a heat treatment (binder removal treatment) for the purpose of removing the binder (binder) used in the granulation. The temperature of the heat treatment was set to 500 ℃. The time of the heat treatment was set to 10 hours.

The molded article after the heat treatment was fired using a tubular atmosphere furnace. The firing temperature was set at 1675 ℃. The firing time was set to 4 hours. The firing atmosphere was set to be a mixed gas atmosphere of nitrogen and hydrogen. The outer diameter and the inner diameter of the fired product after firing were 43mm and 29mm, respectively.

The fired cylindrical fired product was sliced using a multi-wire saw. The thickness of the cylindrical fired product after slicing was set to about 700. Mu.m.

The sliced fired product was polished by a polishing device to adjust the thickness of the fired product. By this adjustment, the fired product becomes a phosphor ceramic layer. The phosphor ceramic layer had a thickness of 53 μm in example 1, 75 μm in example 2, 106 μm in example 3, and 206 μm in comparative example.

The outer diameter and the inner diameter of the phosphor ceramic layers of examples 1 to 3 and comparative examples were 43mm and 29mm, respectively. The phosphor ceramic layers of examples 1 to 3 and comparative examples were dark yellow.

Next, an evaluation of the phosphor ceramic layer will be described.

First, the densities of the phosphor ceramic layers of examples 1 to 3 and comparative examples were evaluated by using an archimedes method. The densities of the phosphor ceramic layers of examples 1 to 3 and comparative example were 4.49g/cm ³ . The densities of the phosphor ceramic layers of examples 1 to 3 and comparative examples were Y ₃ Al ₅ O ₁₂ Theoretical density (4.55 g/cm) ³ ) 98.7%. That is, the densities of the phosphor ceramic layers of examples 1 to 3 and comparative example are Y ₃ Al ₅ O ₁₂ 97% to 100% of theoretical density.

Next, a method for manufacturing the wavelength conversion device is described.

First, a disk-shaped substrate body of Al (diameter: 50mm, thickness: 0.5 mm) was prepared. Next, a substrate body containing TiO dispersed therein was coated with a material having a circular shape (outer diameter: 46mm, inner diameter: 30 mm) using a dispensing apparatus ₂ A light reflecting layer of a particulate silicone-based resin. Here, the silicone resin included in the light reflecting layer also functions as an adhesive for bonding the phosphor ceramic layer to the substrate body.

Thereafter, the phosphor ceramic layer is disposed so as to overlap with the light reflection layer coated in a circular shape. Here, the phosphor ceramic layer was fixed by a metal jig so that the thickness of the light reflection layer became about 50 μm. Then, a heat treatment is performed by using a dryer to cure the light reflection layer. The temperature of the heat treatment at this time was set to 150 ℃. The visible light reflectance of the light reflecting surface, which is a surface included in the light reflecting layer, is 95% or more.

Thus, the wavelength conversion devices of examples 1 to 3 and comparative examples were obtained, each including the phosphor ceramic layers and the substrate of examples 1 to 3 and comparative examples.

Further, an evaluation of the wavelength conversion device will be described.

The wavelength conversion devices of examples 1 to 3 and comparative examples were evaluated using an evaluation device related to a reflection type laser excitation wavelength conversion device. Specifically, in this evaluation device, excitation light (laser light) is irradiated to the rotating wavelength conversion device, and the fluorescence energy of fluorescence emitted from the wavelength conversion device is evaluated by a power meter. Wavelength, output and irradiation spot diameter (1/e) ² ) Set to 455nm, 70W and 1.2mm. In addition, the laser is a gaussian beam. In addition, the rotational speed of the wavelength conversion device was set to 7200rpm. The evaluation device is provided with a diaphragm member for cutting off a part of the fluorescence emitted from the wavelength conversion device. In this case, for example, the distance between the wavelength conversion device and the diaphragm member is 3mm to 100mm, and the aperture diameter of the aperture of the diaphragm member is a circular hole of 5mm to 10 mm.

Fig. 6 is a graph showing the evaluation results of the wavelength conversion devices of examples 1 to 3 and comparative examples of the present embodiment. Specifically, fig. 6 shows the relative fluorescence energy values (after passing through the opening), the relative fluorescence energy values (before passing through the opening), and the coupling efficiencies of the wavelength conversion devices of examples 1 to 3 and comparative examples.

Here, the relative value of fluorescence energy (after passing through the aperture) refers to the relative value of fluorescence energy of fluorescence emitted from each wavelength conversion device after passing through the aperture of the diaphragm member. The fluorescence energy of the fluorescence emitted from the wavelength conversion device of the comparative example after passing through the opening was set to 100%.

The relative fluorescence energy value (before passing through the aperture) is the relative fluorescence energy value of fluorescence emitted from each wavelength conversion device before passing through the aperture of the diaphragm member. The fluorescence energy of the fluorescence emitted from the wavelength conversion device of the comparative example after passing through the opening was set to 100%.

The coupling efficiency is the ratio of the relative fluorescence energy value (after passing through the opening) to the relative fluorescence energy value (before passing through the opening). That is, the coupling efficiency is obtained by dividing the fluorescence energy relative value (after passing through the opening) by the fluorescence energy relative value (before passing through the opening).

In the projector, fluorescence passing through the opening is used as a part of projection light. That is, it is considered that the larger the fluorescence energy relative value (after passing through the opening), the more fluorescence that can be used as projection light of the projector.

As shown in fig. 6, the coupling efficiencies of the wavelength conversion devices of example 1, example 2, example 3, and comparative example were 85%, 86%, 84%, and 81%, respectively. That is, the coupling efficiency in the examples is higher than that in the comparative examples. The higher the coupling efficiency, the more light that passes through the opening, i.e., the smaller the light emission area of the fluorescence emitted from the wavelength conversion device, as shown in fig. 5A and 5B. That is, it is shown that the light emitting areas of the fluorescence emitted from the wavelength conversion devices of examples 1 to 3 are smaller than the light emitting areas of the fluorescence emitted from the wavelength conversion devices of the comparative examples, and that the light utilization efficiency of the wavelength conversion devices of examples is higher.

Further, as shown in FIG. 6, it is apparent that the phosphor ceramic layers of examples 1 to 3 have a thickness in the range of 50 μm to 120 μm, and have a sufficiently high coupling efficiency as compared with the comparative example. That is, by setting the thickness of the phosphor ceramic layer 20 of the present embodiment to be in the range of 50 μm to 120 μm, the wavelength conversion device 1 having high light utilization efficiency can be realized.

The relative values of fluorescence energy (after passing through the opening) of the wavelength conversion devices of example 1, example 2, example 3, and comparative example were 103%, 106%, 105%, and 100%, respectively. That is, the fluorescence energy relative value (after passing through the opening) in any of examples 1 to 3 was higher than that in the comparative example. In examples 1 to 3, the relative values of fluorescence energy (after passing through the opening) were higher for the wavelength conversion devices of example 2 in which the phosphor ceramic layer had a thickness of 76 μm and example 3 in which the phosphor ceramic layer had a thickness of 106 μm.

Further, as shown in FIG. 6, it is apparent that the phosphor ceramic layers of examples 2 and 3 have a thickness in the range of 70 μm to 120 μm, and a sufficiently high relative fluorescence energy value (after passing through the opening) as compared with the comparative example. That is, by setting the thickness of the phosphor ceramic layer 20 of the present embodiment to be in the range of 70 μm to 120 μm, the wavelength conversion device 1 having higher light utilization efficiency can be realized.

The relative values of fluorescence energy (before passing through the opening) of the wavelength conversion devices of example 1, example 2, example 3, and comparative example were 121%, 124%, 125%, and 124%, respectively. The wavelength conversion device of example 1, in which the phosphor ceramic layer had the thinnest thickness of 53 μm, had a lower relative fluorescence energy value (before passing through the opening) than the wavelength conversion devices of examples 2 and 3 and comparative examples. The reason for this is considered to be that: in the wavelength conversion device of example 1, since the thickness of the phosphor ceramic layer is thin, the phosphor ceramic layer cannot sufficiently absorb laser light.

Here, a method for manufacturing the wavelength conversion device according to example 4 of the present embodiment and the efficiency of light use will be further described.

First, a method for manufacturing a phosphor ceramic layer included in the wavelength conversion device of example 4 according to this embodiment is described.

The phosphor ceramic layers of example 4 were each composed of (Y) _0.997 Ce _0.003 ) ₃ Al ₅ O ₁₂ The first crystalline phase is shown. In addition, the phosphor ceramic layers of example 4 are each composed of Ce ³⁺ And activating the fluorescent body.

In the case of example 4, the catalyst was prepared by reacting a compound (Y _0.997 Ce _0.003 ) ₃ Al ₅ O ₁₂ The same procedure as in examples 1 to 3 was followed except that the raw materials were weighed to obtain a baked product. That is, the phosphor ceramic layers of examples 1 to 3 are different from the phosphor ceramic layer of example 4 mainly in the composition ratio of Y to Ce.

The phosphor ceramic layer of example 4 had a thickness of 103 μm.

The outer diameter and the inner diameter of the phosphor ceramic layer of example 4 were 41mm and 27mm. In addition, the phosphor ceramic layer of example 4 was dark yellow.

Next, an evaluation of the phosphor ceramic layer will be described.

First, the density of the phosphor ceramic layer of example 4 was evaluated by using archimedes' method. The phosphor ceramic layer of example 4 had a density of 4.48g/cm ³ . In addition, the density of the phosphor ceramic layers of example 4 was Y ₃ Al ₅ O ₁₂ Theoretical density (4.55 g/cm) ³ ) 98.4% of (C). That is, the phosphor ceramic layer of example 4 has a density of Y ₃ Al ₅ O ₁₂ 97% to 100% of theoretical density.

As described above, the phosphor ceramic layer 20 of the present embodiment is composed of a phosphor having Ce ³⁺ Ce (Ce) ⁴⁺ YAG composition of (a) that is, the phosphor ceramic layer 20 contains Ce ³⁺ Ce (Ce) ⁴⁺ . Therefore, the phosphor ceramic layer of example 4 was then subjected to Ce using a hard X-ray XAFS apparatus ³⁺ Presence ratio and Ce ⁴⁺ The presence ratio was evaluated. Specifically, the XAFS spectrum of the phosphor ceramic layer of example 4 was obtained in the range of 5687eV to 5777eV using a hard X-ray XAFS device. By performing Ce on the obtained XAFS spectrum ³⁺ Reference spectrum of (d) and Ce ⁴⁺ Fitting analysis of reference spectra of (2) to Ce ³⁺ Presence ratio and Ce ⁴⁺ The presence ratio was evaluated. In addition, to obtain Ce ³⁺ Reference spectrum of (d) and Ce ⁴⁺ Is the same for CeO ₂ CeF (Certif) ₃ Evaluation was performed.

Table 1 shows Ce for the phosphor ceramic layer of example 4 ³⁺ Presence ratio and Ce ⁴⁺ A table of ratios exists. As shown in Table 1, ce in the phosphor ceramic layer of example 4 ³⁺ Presence ratio and Ce ⁴⁺ The presence ratio was 78.3% and 21.7%, respectively. The phosphor ceramic layer of example 4 satisfies Ce ³⁺ ×100％/(Ce ³⁺ +Ce ⁴⁺ ) More than or equal to 60 percent, namely Ce ³⁺ The presence ratio is 60% or more.

TABLE 1

Ce ³⁺ Is the ratio of existence of (3)	Ce ⁴⁺ Is the ratio of existence of (3)
		78.3％	21.7％

Next, a method for manufacturing the wavelength conversion device of example 4 is described.

First, as the light reflection layer, a disk-shaped substrate body (diameter: 50mm, thickness: 0.5 mm) of Ag-coated Al was prepared. Further, a screw hole is formed in the center of the substrate body. Next, a phosphor ceramic layer is provided on the substrate body.

A disk-shaped first plate member (outer diameter: 26.5mm, thickness: 100 μm) of Al having a screw hole formed in the center thereof was provided inside the phosphor ceramic layer. The phosphor ceramic layer is a phosphor ring, and the first plate member is provided inside the ring shape. Further, a second plate member (outer diameter: 29mm, thickness: 200 μm) in the shape of a disk of Al having a screw hole formed in the center thereof was provided so as to overlap the phosphor ceramic layer and the first plate member. The substrate main body, the first plate member, and the second plate member are screwed. Thus, the phosphor ceramic layer was fixed, and a wavelength conversion device was obtained. That is, in the wavelength conversion device of example 4, the phosphor ceramic layer is sandwiched and fixed between the substrate main body and the second plate member.

Thus, a phosphor ceramic layer and a wavelength conversion device of example 4 were obtained.

Further, an evaluation of the wavelength conversion device will be described.

The wavelength conversion device of example 4 was evaluated in the same manner as in examples 1 to 3.

Fig. 7 is a graph showing the evaluation result of the wavelength conversion device of example 4 according to the present embodiment. Specifically, fig. 7 shows the relative fluorescence energy value (after passing through the aperture), the relative fluorescence energy value (before passing through the aperture), and the coupling efficiency of the wavelength conversion device of example 4. For comparison, the fluorescence energy relative values (after passing through the opening), the fluorescence energy relative values (before passing through the opening), and the coupling efficiencies of the wavelength conversion devices of examples 1 to 3 and comparative example are also shown in fig. 7.

Here, the relative value of fluorescence energy (after passing through the aperture) refers to the relative value of fluorescence energy of fluorescence emitted from the wavelength conversion device after passing through the aperture of the diaphragm member. The fluorescence energy of the fluorescence emitted from the wavelength conversion device of the comparative example after passing through the opening was set to 100%.

The relative fluorescence energy value (before passing through the aperture) is the relative fluorescence energy value of fluorescence emitted from the wavelength conversion device before passing through the aperture of the diaphragm member. The fluorescence energy of the fluorescence emitted from the wavelength conversion device of the comparative example after passing through the opening was set to 100%.

The coupling efficiency is the ratio of the relative fluorescence energy value (after passing through the opening) to the relative fluorescence energy value (before passing through the opening). That is, the coupling efficiency is a value obtained by dividing the fluorescence energy relative value (after passing through the opening) by the fluorescence energy relative value (before passing through the opening).

As shown in fig. 7, the coupling efficiency of the wavelength conversion device of example 4 was 85%. As described above, the coupling efficiency of the wavelength conversion device of the comparative example was 81%. In the wavelength conversion device of example 4 having higher coupling efficiency, more light passes through the opening portion among the generated fluorescence, and the light emitting area of the fluorescence is smaller. For example, as shown in fig. 5A and 5B, in the wavelength conversion device of embodiment 4, the light passing through the aperture 2a of the diaphragm member 2 is large, and thus the light that can be used as projection light of the projector 100 is large. That is, it is shown that the wavelength conversion device of example 4 has high light utilization efficiency.

Further, the relative fluorescence energy values (after passing through the opening) and (before passing through the opening) of the wavelength conversion device of example 4 were 108% and 128%, respectively. This value is higher than the fluorescence energy relative value (after passing through the opening) of the wavelength conversion devices of examples 1 to 3 (before passing through the opening).

As described above, the phosphor ceramic layer of example 4 was Ce ³⁺ The presence ratio is above 60%, ce ⁴⁺ The presence ratio of (2) is less than 40%, less. Thus, from Ce ⁴⁺ The non-luminescence relaxation loss caused is reduced, thus Ce ³⁺ The phosphor ceramic layer of example 4 having a ratio of 60% or more has a higher luminous efficiency. Therefore, by providing such a phosphor ceramic layer, the wavelength conversion device of example 4 can improve the light use efficiency. Further, in the case where the projector includes such a wavelength conversion device 1, the light use efficiency of the projector can be improved. For example, a projector with low power consumption can be realized.

In addition, due to Ce ⁴⁺ The resulting non-luminescent relaxation loss was reduced, and therefore the heat generation of the phosphor ceramic layer of example 4 was reduced. Therefore, in the projector including such a phosphor ceramic layer, the maximum input energy of the excitation light L1 can be increased, that is, a projector with high output can be realized.

Modification 1

The phosphor ceramic layer 20 of the embodiment is composed of only the first crystal phase, but is not limited thereto. Here, a wavelength conversion device 1a including a phosphor ceramic layer 20a including a first crystal phase and a second crystal phase will be described.

[ construction of wavelength conversion device ]

First, the configuration of the wavelength conversion device 1a according to the present modification will be described with reference to the drawings. Fig. 8 is a perspective view of a wavelength conversion device 1a according to this modification. Fig. 9 is a cross-sectional view showing a cut surface of the wavelength conversion device 1a at line IX-IX of fig. 8.

The wavelength conversion device 1a of the present modification has the same configuration as the wavelength conversion device 1 of the embodiment except that the phosphor ceramic layer 20a is provided. That is, as shown in fig. 8 and 9, the wavelength conversion device 1a includes a substrate 10 having a light reflection surface 13, a phosphor ceramic layer 20a, and an antireflection layer 30.

In the present modification, the wavelength conversion device 1a is also a phosphor wheel for a projector that receives the excitation light L1 and emits reflected light including fluorescence.

The phosphor ceramic layer 20a includes a first crystal phase and a second crystal phase. More specifically, in the present modification, the phosphor ceramic layer 20a is composed of a first crystal phase and a second crystal phase.

The first crystal phase has the constitution described in the embodiment mode.

In addition, the second crystal phase is a crystal phase having a structure different from the garnet structure. That is, the second crystal phase has a structure different from that of the first crystal phase. Therefore, the refractive index of the first crystal phase and the refractive index of the second crystal phase are different from each other.

When the area of the image representing the phosphor ceramic layer 20a is set to 100% as a whole in the case of cross-sectional observation of the phosphor ceramic layer 20a, the area representing the first crystal phase is, for example, 10% to 99%. The area of the first crystal phase is not limited to this, and may be, for example, 75% to 98%, or 85% to 95%. That is, the phosphor ceramic layer 20a of the present modification mainly includes the first crystal phase.

As an example, the second crystal phase of the present modification is a crystal phase having a perovskite structure, but not limited to this, and may be a crystal phase having a structure different from the garnet structure and the perovskite structure.

Perovskite structure is defined by EFO ₃ A crystal structure represented by the general formula (I). The element E is a rare earth element such as Ca, Y, la, ce, pr, nd, sm, eu, gd, tb and Lu, and the element F is an element such as Mg, al, si, ga and Sc. Examples of such garnet structures include: YAP (yttrium-aluminum-perovskite (Yttrium Aluminum Perovskite)) and the like. In the present modification, the second crystal phase is composed of (Y _1-y Ce _y )AlO ₃ (0.ltoreq.y < 0.1), namely YAP.

Further, the second crystal phase may be a solid solution of a plurality of perovskite crystal phases different in chemical composition.

In addition, the second crystalline phase may comprise a compound having a chemical composition deviating from the general formula EFO described above ₃ A crystal phase represented as a crystal phase.

The phosphor ceramic layer 20a of the present modification example is composed of only the first crystal phase and the second crystal phase, that is, does not include a crystal phase having a structure different from the garnet structure and the perovskite structure.

In the present modification, the material showing the second crystal phase is YAP as an example, but is not limited thereto. The material representing the second crystal phase may be selected so that the difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase having a garnet structure (YAG, in this case) is 0.05 to 0.5. Thus, as described above, the refractive index of the first crystal phase and the refractive index of the second crystal phase are different from each other. The difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase is preferably 0.06 to 0.3, more preferably 0.07 to 0.15.

In addition, for example, in the case where the second crystal phase of the present modification is a crystal phase having a structure different from the garnet structure and the perovskite structure, al may be used as a material indicating the second crystal phase ₂ O ₃ 、Y ₂ O ₃ 、Y ₄ Al ₂ O ₉ 、Lu ₂ O ₃ Lu (Lu) ₄ Al ₂ O ₉ Etc.

The phosphor ceramic layer 20a receives light, which is the excitation light L1, and enters from above the wavelength conversion device 1a, and emits fluorescence. More specifically, by irradiating the phosphor ceramic layer 20a with light emitted from an excitation light source described later as excitation light L1, fluorescence as wavelength-converted light is emitted from the phosphor ceramic layer 20 a. That is, the wavelength-converted light emitted from the phosphor ceramic layer 20a is light having a wavelength longer than that of the excitation light L1.

In the present modification, the wavelength-converted light emitted from the phosphor ceramic layer 20a includes fluorescence as yellow light. The phosphor ceramic layer 20a absorbs light having a wavelength of 380nm to 490nm, for example, and emits fluorescence as yellow light having a fluorescence peak wavelength in a region having a wavelength of 490nm to 580 nm. By forming the phosphor ceramic layer 20a from YAG and YAP, it is easy to realize the phosphor ceramic layer 20a that emits fluorescence having a fluorescence peak wavelength in a region having a wavelength of 490nm to 580 nm.

The x-coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20a may be 0.415 or less, more preferably 0.410 or less, and still more preferably 0.408 or less. If the x-coordinate of the chromaticity diagram of the wavelength-converted light emitted from the phosphor ceramic layer 20a is the above-described value, the temperature quenching of the phosphor ceramic layer 20a becomes small, and thus the phosphor ceramic layer 20a having high luminous efficiency can be realized.

The density of the phosphor ceramic layer 20a may be 95% to 100% of the theoretical density, and more preferably 97% to 100% of the theoretical density. Here, the theoretical density refers to a density in the case where atoms in a layer are desirably aligned. In other words, the theoretical density refers to a density assuming that there is no void in the phosphor ceramic layer 20a, which is a value calculated using a crystal structure. For example, when the density of the phosphor ceramic layer 20a is 99%, the remaining 1% corresponds to a void. That is, the higher the density of the phosphor ceramic layer 20a, the fewer the voids. If the density of the phosphor ceramic layer 20a is in the above range, the total amount of fluorescence emitted from the phosphor ceramic layer 20a increases, and thus the wavelength conversion device 1a and the projector with a larger amount of emitted light can be provided.

Further, the theoretical density refers to the theoretical density of the first crystal phase having a garnet structure.

The density of the phosphor ceramic layer 20a may be 4.32g/cm ³ ～4.55g/cm ³ More preferably 4.41g/cm ³ ～4.55g/cm ³ . As shown in this modification, in the case where the phosphor ceramic layer 20a is composed of YAG and YAP, if the density of the phosphor ceramic layer 20a is in the above range, the density of the phosphor ceramic layer 20a becomes 95% to 100% and 97% to 100%, respectively. By setting the density of the phosphor ceramic layer 20a to the above range, the excitation light L1 absorbed by the phosphor ceramic layer 20a can be efficiently converted into fluorescence. That is, the phosphor ceramic layer 20a having high luminous efficiency is realized.

The thickness (length in the z-axis direction) of the phosphor ceramic layer 20a is preferably 50 μm or more and less than 150 μm, more preferably 50 μm or more and less than 120 μm. The phosphor ceramic layer preferably has a film thickness of 70 μm or more and less than 120 μm, more preferably 80 μm or more and less than 110 μm.

[ construction of projector ]

The wavelength conversion device 1a configured as described above is used in a projector in the same manner as the wavelength conversion device 1 of the embodiment. That is, the wavelength conversion device 1a of the present modification may be used instead of the wavelength conversion device 1 of the embodiment.

Examples (example)

Here, a manufacturing method and light use efficiency will be described in the wavelength conversion devices of examples 5 and 6. The wavelength conversion device of example 5 has the same configuration as the wavelength conversion device 1a of the present modification, and the wavelength conversion device of example 6 has the same configuration as the wavelength conversion device 1 of the embodiment.

First, a method for manufacturing a phosphor ceramic layer included in the wavelength conversion device of examples 5 and 6 is described.

The phosphor ceramic layer of example 5 is mainly composed of (Y _0.997 Ce _0.003 ) ₃ Al ₅ O ₁₂ The indicated crystalline phase (i.e. the first crystalline phase). In addition, as described above, the phosphor ceramic layer of example 5 also contains a second crystal phase. The phosphor ceramic layer of example 6 is composed of (Y) _0.997 Ce _0.003 ) ₃ Al ₅ O ₁₂ The indicated crystalline phase (i.e. the first crystalline phase). In addition, examples5 and 6 are made of Ce ³⁺ And activating the fluorescent body.

The same raw materials as those used in examples 1 to 3 were used for the phosphor ceramic layers of examples 5 and 6.

First, the compound (Y) is formed into a stoichiometric composition _0.9953 Ce _0.0047 ) ₃ Al ₅ O ₁₂ The above raw materials were weighed. Next, the above-described raw materials were mixed in the same manner as in examples 1 to 3, to obtain a slurry-like mixed raw material.

Next, in example 5, a granulated mixed material was obtained by a method not using a spray drying apparatus. Specifically, 100g of the mixed material dried by a dryer was charged into an alumina mortar. Then, a solution obtained by dissolving polyvinyl alcohol in water at a ratio of 0.5 wt% was used as a polyvinyl alcohol solution, and 18mL of the polyvinyl alcohol solution was further charged into an alumina mortar. Thereafter, the mixed raw material was mixed with a polyvinyl alcohol solution using a pestle. Next, the mixture of the mixed raw material and the polyvinyl alcohol solution was sieved using a sieve having a mesh size of 512. Mu.m. As a result, a mixture of the polyvinyl alcohol solution and the mixed raw material having a particle size of about 512 μm or less was obtained. Thereafter, the mixture was treated with a dryer set at 105℃for 30 minutes to remove water. Thus, the granulated mixed raw material used in example 5 was obtained. In example 6, the mixed raw materials were granulated in the same manner as in examples 1 to 3, to obtain granulated mixed raw materials.

The phosphor ceramic layers of examples 5 and 6 were temporarily molded in the same manner. Specifically, the granulated mixed raw material was molded into a cylinder by an electric hydraulic press (EMP-5, manufactured by Mi-Shang Seiko Co., ltd.) and a cylinder mold (outer diameter: 66mm, inner diameter: 46mm, height: 130 mm). The pressure during molding was set to 5MPa. Next, the molded article after the temporary molding was subjected to main molding by a cold isostatic pressing device. The pressure at the time of main molding was set to 300MPa. The molded article after the main molding is subjected to a heat treatment (binder removal treatment) for the purpose of removing the binder (binder) used in the granulation. The temperature of the heat treatment was set to 500 ℃. The time of the heat treatment was set to 10 hours.

The molded article after the heat treatment was fired using a tubular atmosphere furnace. The firing temperature was set at 1675 ℃. The firing time was set to 4 hours. The firing atmosphere was set to be a mixed gas atmosphere of nitrogen and hydrogen. The outer diameter and the inner diameter of the fired product after firing were 49mm and 35mm, respectively.

In examples 5 and 6, the fired product after firing was subjected to heat treatment at a temperature of 1000 ℃.

The sliced fired product was polished by a polishing device, and the thickness of the fired product was adjusted. The thickness of the phosphor ceramic layer was 118 μm in example 5 and 117 μm in example 6.

The outer diameter and the inner diameter of the phosphor ceramic layers of examples 5 and 6 were 49mm and 35mm, respectively. The phosphor ceramic layers of examples 5 and 6 were dark yellow.

Next, an evaluation of the phosphor ceramic layer will be described.

First, the density of the phosphor ceramic layers of examples 5 and 6 was evaluated by using an archimedes method. The densities of the phosphor ceramic layers of examples 5 and 6 were 4.48g/cm, respectively ³ 4.42g/cm ³ . The densities of the phosphor ceramic layers in examples 5 and 6 were Y ₃ Al ₅ O ₁₂ Theoretical density (4.55 g/cm) ³ ) 98.4% and 97.1% of (a). That is, the density of the phosphor ceramic layers of examples 5 and 6 was Y ₃ Al ₅ O ₁₂ 97% to 100% of theoretical density.

Next, a cross-sectional SEM image of the phosphor ceramic layer of example 5 was evaluated using a Scanning Electron Microscope (SEM).

Fig. 10 is an SEM image showing a cross section of the phosphor ceramic layer of example 5 of the present modification. Fig. 10 (a) shows an SEM image of a wide cross section of the phosphor ceramic layer of example 5. The SEM image shown in fig. 10 (a) corresponds to an image of a region surrounded by a rectangular broken line in the cross-sectional view shown in fig. 9. Fig. 10 (b) is an enlarged SEM image of the area surrounded by the rectangle of the one-dot chain line in fig. 10 (a). Fig. 10 (c) is an enlarged SEM image of the region surrounded by the rectangle of the two-dot chain line in fig. 10 (a).

Here, the phosphor ceramic layer 20a of the present modification example, which is the phosphor ceramic layer of example 5, includes a single-phase portion and a mixed-phase portion separated from the single-phase portion. Fig. 10 (b) shows a single-phase portion, and fig. 10 (c) shows a mixed-phase portion.

In the SEM image of fig. 10, the darker areas correspond to the first crystal phase having the garnet structure, and the lighter areas correspond to the second crystal phase having the perovskite structure. In the SEM image in fig. 10, the region with the deepest color corresponds to a void.

The single-phase portion is provided with only the first crystal phase having a garnet structure and the first crystal phase in the second crystal phase having a structure different from the garnet structure (in this case, a perovskite structure). More specifically, only the first crystal phase is provided in the single-phase portion, and other crystals having a structure different from the garnet structure and the perovskite structure are not provided.

In addition, both the first crystal phase and the second crystal phase are mixed in the mixed phase portion. More specifically, only the first crystal phase and the second crystal phase are mixed and provided in the mixed phase portion. In addition, the mixed phase portion may be provided with both the first crystal phase and the second crystal phase and further other crystal phases having a structure different from the garnet structure and the perovskite structure in a mixed manner.

The mixed phase portion of embodiment 5 is formed by mixing the first crystal phase and the second crystal phase in a random intertwined structure, but the present invention is not limited thereto, and the first crystal phase and the second crystal phase may be formed by mixing them in a periodically arranged structure.

In addition, the phosphor ceramic layer in example 5 includes a plurality of mixed phase portions. The areas surrounded by the broken lines in fig. 10 (a) correspond to the mixed phase portions, respectively.

The respective peripheries of the plurality of mixed-phase portions are surrounded by a single-phase portion. The shape of the single-phase portion and the plurality of mixed-phase portions may be regarded as island-in-sea shape. In this case, the single-phase portion corresponds to the sea, and the plurality of mixed-phase portions corresponds to the island.

In addition, it is sufficient if more second crystal phases than the first crystal phases are provided in the mixed phase portion. For example, the ratio of the first crystal phase to the second crystal phase in the mixed phase section is as follows. When the area of the image representing the mixed phase portion is set to 100% as a whole in the case of cross-sectional observation of the phosphor ceramic layer of example 5 (for example, fig. 10), the area representing the second crystal phase is, for example, 10% to 99%. The area of the second crystal phase is not limited to this, and may be, for example, 70% to 95%, or 80% to 90%. That is, the second crystal phase is mainly provided in the mixed phase portion of the present modification.

In this way, both the first crystal phase having a garnet structure and the second crystal phase having a perovskite structure are mixed and provided in the mixed phase portion. As described above, the refractive index of the first crystal phase and the refractive index of the second crystal phase are different from each other. Therefore, the refractive index of the single-phase portion where only the first crystal phase is provided and the refractive index of the mixed-phase portion are different from each other. In this modification, the refractive index of YAG is 1.83 and the refractive index of yap is 1.91, so that the refractive index of the single-phase portion is lower than that of the mixed-phase portion.

Further, the size of the mixed phase portion will be described. The size of the mixed phase portion indicates the length of the mixed phase portion in the longitudinal direction in the SEM image shown in fig. 10. The size of the mixed phase portion refers to the length indicated by the double arrow in fig. 10, for example. The size of the mixed phase portion is preferably 0.5 μm or more and less than 500 μm, more preferably 1 μm or more and less than 300 μm, still more preferably 2 μm or more and less than 100 μm.

Thus, the phosphor ceramic layer (phosphor ceramic layer 20 a) of example 5 includes the first crystal phase and the second crystal phase, and fig. 10 shows a case where a single-phase portion and a mixed-phase portion are provided. On the other hand, the phosphor ceramic layer of example 6 is composed of only the first crystal phase. Therefore, it was confirmed that the mixed phase portion was not provided in the phosphor ceramic layer of example 6.

Next, a method for manufacturing the wavelength conversion device of examples 5 and 6 is described.

First, as the light reflection layer, a disk-shaped substrate body (diameter: 50mm, thickness: 0.5 mm) of Al coated with Ag was prepared. Further, a screw hole is formed in the center of the substrate body. Next, a phosphor ceramic layer is provided on the substrate body.

A third plate member (34.5 mm in outer diameter, 100 μm in thickness) in the shape of a disk of Al with a screw hole formed in the center thereof was provided inside the phosphor ceramic layer. The phosphor ceramic layer is a phosphor ring, and the third plate member is provided inside the ring shape. Further, a disk-shaped fourth plate member (outer diameter: 39mm, thickness: 200 μm) of Al having a screw hole formed in the center thereof was provided so as to overlap the phosphor ceramic layer and the third plate member. The substrate main body, the third plate member, and the fourth plate member are screwed. Thus, the phosphor ceramic layer was fixed, and a wavelength conversion device was obtained. That is, in the wavelength conversion devices of examples 5 and 6, the phosphor ceramic layer is sandwiched and fixed between the substrate main body and the fourth plate member.

Further, an evaluation of the wavelength conversion device will be described.

The wavelength conversion devices of examples 5 and 6 were evaluated in the same manner as in examples 1 to 3.

Fig. 11 is a graph showing the evaluation results of the wavelength conversion devices of examples 5 and 6 according to this modification. Specifically, fig. 11 shows the relative fluorescence energy values (after passing through the aperture), the relative fluorescence energy values (before passing through the aperture), and the coupling efficiencies of the wavelength conversion devices of examples 5 and 6.

Here, the relative value of fluorescence energy (after passing through the aperture) refers to the relative value of fluorescence energy of fluorescence emitted from each wavelength conversion device after passing through the aperture of the diaphragm member. The fluorescence energy of the fluorescence emitted from the wavelength conversion device of example 6 after passing through the opening was set to 100%.

The relative fluorescence energy value (before passing through the aperture) is the relative fluorescence energy value of fluorescence emitted from each wavelength conversion device before passing through the aperture of the diaphragm member. The fluorescence energy of the fluorescence emitted from the wavelength conversion device of example 6 after passing through the opening was set to 100%.

As shown in fig. 11, the relative values of fluorescence energy (after passing through the opening) of the wavelength conversion devices of examples 5 and 6 were 101% and 100%, respectively. The relative fluorescence energy values (before passing through the opening) of the wavelength conversion devices of examples 5 and 6 were 117% and 122%, respectively.

The coupling efficiency of the wavelength conversion device of example 5, which corresponds to the wavelength conversion device 1a of the present modification, was 87%. The coupling efficiency of the wavelength conversion device of example 6, which corresponds to the wavelength conversion device 1 of the embodiment, was 82%.

As described above, the phosphor ceramic layer (phosphor ceramic layer 20 a) included in the wavelength conversion device of example 5 is composed of the first crystal phase and the second crystal phase having different refractive indices.

In this way, since regions having different refractive indexes are generated in the phosphor ceramic layer 20a, the excitation light L1 and the fluorescence are more likely to scatter. As a result, light guiding in the planar direction (i.e., the x-axis direction or the y-axis direction) of the layers shown in fig. 5A and 5B in the embodiment is suppressed, and the light emitting area of the phosphor ceramic layer 20a is reduced. Therefore, the coupling efficiency of the wavelength conversion device of example 5 is higher than that of the wavelength conversion device of example 6. That is, the wavelength conversion device (wavelength conversion device 1 a) of example 5, which is smaller in etendue and higher in light use efficiency, was realized. In the case where the projector includes such a wavelength conversion device 1a, the light use efficiency of the projector can be further improved.

The phosphor ceramic layer 20a includes a single-phase portion and a mixed-phase portion separated from the single-phase portion. Only the first crystal phase of the first crystal phase and the second crystal phase is provided in the single-phase portion, and both the first crystal phase and the second crystal phase are provided in the mixed-phase portion in a mixed manner. The refractive index of such a single-phase portion and the refractive index of the mixed-phase portion are different from each other.

In this way, since regions having different refractive indexes are generated in the phosphor ceramic layer 20a, the excitation light L1 and the fluorescence are more likely to scatter. As a result, the light emitting area of the phosphor ceramic layer 20a is further reduced. Thus, the wavelength conversion device 1a is realized which is smaller in etendue and higher in light utilization efficiency.

When the size of the mixed phase portion is in the above range, the excitation light L1 and the fluorescence are more likely to be scattered.

The phosphor ceramic layer 20a includes a plurality of mixed phase portions. The respective peripheries of the plurality of mixed-phase portions are surrounded by a single-phase portion.

Thus, the excitation light L1 and the fluorescence are more easily scattered. As a result, the light emitting area of the phosphor ceramic layer 20a is further reduced. Thus, the wavelength conversion device 1a is realized which is smaller in etendue and higher in light utilization efficiency.

The above results indicate that: the coupling efficiency of the wavelength conversion device 1a increases not only due to the light guiding suppression effect caused by the thin film thickness of the phosphor ceramic layer 20a, but also due to the light guiding suppression effect of the phosphor ceramic layer 20a itself. Namely, it is shown that: even if the film thickness of the phosphor ceramic layer 20a is not controlled, the coupling efficiency of the wavelength conversion device 1a increases.

The difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase is 0.05 to 0.5.

In addition, the second crystal phase is composed of (Y _1-y Ce _y )AlO ₃ (0.ltoreq.y < 0.1).

Thus, the difference between the refractive index of the material representing the second crystal phase and the refractive index of the material representing the first crystal phase can be easily set to the above range.

Modification 2

Further, a phosphor ceramic layer 20b having a different structure from the phosphor ceramic layers 20 and 20a will be described.

Fig. 12 is a perspective view of a phosphor ceramic member according to this modification.

As an example, the phosphor ceramic member of the present modification is a phosphor ceramic layer 20b having a layered shape.

The phosphor ceramic layer 20b is used for a projector in the same manner as the phosphor ceramic layers 20 and 20a shown in embodiment and modification 1.

The phosphor ceramic layer 20b has the same configuration as the phosphor ceramic layer 20a of modification 1 except for the following points. In particular, this is Ce ³⁺ The presence ratio is 60% or more.

That is, the phosphor ceramic layer 20b includes a first crystal phase having a garnet structure and a second crystal phase having a structure other than the garnet structure. The refractive indices of the first crystal phase and the second crystal phase are different from each other. In the present modification, the first crystal phase and the second crystal phase are crystal phases represented by YAG and YAP, respectively, and the phosphor ceramic layer 20b mainly includes the first crystal phase. The density of the phosphor ceramic member (phosphor ceramic layer 20 b) may be 95% to 100% of the theoretical density, and more preferably 97% to 100% of the theoretical density. The thickness of the phosphor ceramic member (phosphor ceramic layer 20 b) may not be particularly limited, but is preferably 50 μm or more and less than 500 μm, more preferably 50 μm or more and less than 300 μm in the case of limiting. The film thickness is more preferably 50 μm or more and less than 120 μm.

The phosphor ceramic member (phosphor ceramic layer 20 b) has the above-described configuration. Therefore, when the phosphor ceramic layer 20b is used for a projector and is irradiated with excitation light, regions having different refractive indexes are generated in the phosphor ceramic layer 20b, and therefore, the excitation light and the fluorescence are further scattered. As a result, light guiding in the planar direction (i.e., the x-axis direction or the y-axis direction) of the layers shown in fig. 5A and 5B of the embodiment is suppressed, and the light emitting area of the phosphor ceramic layer 20B is reduced. Therefore, the phosphor ceramic member has a smaller etendue and a higher light utilization efficiency. When the projector includes such a phosphor ceramic member (phosphor ceramic layer 20 b), the light utilization efficiency of the projector can be further improved.

The phosphor ceramic layer 20b is composed of a material having Ce ³⁺ Ce (Ce) ⁴⁺ Is composed of YAG and YAP, i.e. the phosphor ceramic layer 20b contains Ce ³⁺ Ce (Ce) ⁴⁺ . Here, the phosphor ceramic layer 20b satisfies Ce ³⁺ ×100％/(Ce ³⁺ +Ce ⁴⁺ ) More than or equal to 60 percent, namely Ce ³⁺ The presence ratio is 60% or more.

Ce is as follows ³⁺ The phosphor ceramic layer 20b having a ratio of 60% or more is composed of Ce ⁴⁺ The non-emission relaxation loss caused is reduced, and thus the light emission efficiency becomes high. Further, in the projector including such a phosphor ceramic layer 20b, the light utilization efficiency can be improved. For example, a projector with low power consumption can be realized.

In addition, from Ce ⁴⁺ The resulting non-emission relaxation loss is reduced, and therefore, the heat generation of the phosphor ceramic layer 20b is reduced. Therefore, in the projector including the phosphor ceramic layer 20b, the maximum input energy of the excitation light can be increased, that is, a projector with high output can be realized.

(other embodiments)

The wavelength conversion device and the like of the present invention have been described above based on the embodiments and modifications, but the present invention is not limited to these embodiments and modifications. The scope of the present invention includes, without departing from the spirit of the present invention, a mode in which various modifications which can be conceived by those skilled in the art are implemented in the embodiments and modifications, and other modes in which some of the constituent elements in the embodiments and modifications are combined.

In the embodiment, the light source is a semiconductor laser light source, but the present invention is not limited to this, and may be an LED light source.

In addition, in the above-described embodiments, various modifications, substitutions, additions, omissions, and the like may be made within the scope of the claims or their equivalents.

Claims

1. A wavelength conversion device for a projector and emitting reflected light including fluorescence upon receiving excited light,

wherein the light emitting diode comprises a substrate having a light reflecting surface and a phosphor ceramic layer,

the phosphor ceramic layer is located above the light reflecting surface and comprises a first crystalline phase having a garnet structure,

the visible light reflectivity of the light reflecting surface is 95-100%,

the density of the phosphor ceramic layer is 97% -100% of the theoretical density,

the phosphor ceramic layer has a film thickness of 50 μm or more and less than 120 μm,

the substrate has a substrate body and a light reflecting layer,

the light reflecting surface is constituted by a surface included in the light reflecting layer,

the light reflection layer contains light scattering particles or Ag;

the phosphor ceramic layer further comprises a second crystalline phase having a structure different from the garnet structure;

the phosphor ceramic layer includes a single-phase portion and a mixed phase portion separated from the single-phase portion,

Only the first crystal phase among the first crystal phase and the second crystal phase is provided in the single-phase portion,

the mixed phase portion is provided with both the first crystal phase and the second crystal phase in a mixed manner;

the mixed phase portion is provided with both the first crystal phase and the second crystal phase in a mixed manner in a structure of randomly intertwining.

2. The wavelength conversion device according to claim 1, wherein the phosphor ceramic layer has a film thickness of 70 μm or more and less than 120 μm.

3. The wavelength conversion device according to claim 1, further comprising an antireflection layer that is located above the phosphor ceramic layer and prevents reflection of the excitation light.

4. The wavelength conversion device of claim 1, wherein the phosphor ceramic layer is formed of a material selected from the group consisting of (Y _1-x Ce _x ) ₃ Al ₅ O ₁₂ The first crystal phase is expressed as 0.001-0.1.

5. The wavelength conversion device of claim 1, wherein the phosphor ceramic layer has a density of 4.41g/cm ³ ～4.55g/cm ³ 。

6. The wavelength conversion device of claim 1, wherein said phosphor ceramic layer comprises a plurality of said mixed phase portions,

the respective circumferences of the plurality of mixed-phase portions are surrounded by the single-phase portion.

7. The wavelength conversion device according to claim 1, wherein a difference between a refractive index of the material representing the second crystal phase and a refractive index of the material representing the first crystal phase is 0.05 to 0.5.

8. The wavelength conversion device of claim 1, wherein the second crystalline phase is formed from (Y _1-y Ce _y )AlO ₃ The expressed crystal phase is that y is more than or equal to 0 and less than 0.1.

9. The wavelength conversion device according to any one of claims 1 to 8, wherein the phosphor ceramic layer comprises Ce ³⁺ Ce (Ce) ⁴⁺ ，

Satisfy Ce ³⁺ ×100％/(Ce ³⁺ +Ce ⁴⁺ )≥60％。

10. The wavelength conversion device of claim 1, wherein,

the phosphor ceramic layer has a circular ring shape in a plan view of the light reflecting surface,

the light reflection layer is provided so as to spread inward and outward of the circular ring shape of the phosphor ceramic layer in the plan view.

11. A projector comprising an excitation light source that emits excitation light and the wavelength conversion device according to any one of claims 1 to 10 that receives the excitation light and emits reflected light including fluorescence.

12. A phosphor ceramic member for a projector,

wherein the phosphor ceramic member is the phosphor ceramic layer used in the wavelength conversion device according to any one of claims 1 to 10.