JP2019008045A - Wavelength conversion element, light source device, and projection type device - Google Patents

Abstract

To provide a wavelength conversion element with high reliability.SOLUTION: A wavelength conversion element 40 comprises: a substrate 41; a wavelength conversion unit 42 that includes a wavelength conversion layer emitting light with a wavelength different from the wavelength of incident light and a metal layer provided between the wavelength conversion layer and substrate 41, and is formed into a rectangular shape; and a connection unit 43 that connects the substrate 41 with the metal layer. When seen from a first direction perpendicular to one face of the substrate 41, the connection unit 43 is arranged inside the wavelength conversion unit 42 at least at the corners of the wavelength conversion unit 42.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wavelength conversion element, a light source device, and a projection type device.

  In recent years, as a light source device mounted on a projection type device, an apparatus including a light source and a wavelength conversion element that emits light having a wavelength different from the wavelength of the light by the light emitted from the light source is known ( For example, see Patent Document 1).

The light source device described in Patent Literature 1 includes a light source (semiconductor laser) that emits excitation light (blue light) and a wavelength conversion element that emits fluorescence including red light and green light when the excitation light is incident. The wavelength conversion element includes a wavelength conversion layer, a reflective layer, a substrate, and an adhesive layer.
The wavelength conversion layer includes a phosphor inside and is formed in a rectangular shape. The reflection layer is formed on the wavelength conversion layer and reflects fluorescence emitted from the wavelength conversion layer. The wavelength conversion layer is fixed to the substrate by an adhesive layer.

JP, 2006-186523, A

  However, since the wavelength conversion element described in Patent Document 1 is considered to have a different coefficient of thermal expansion of the substrate and that of the wavelength conversion layer, heat generation due to incidence of excitation light causes the substrate and the wavelength conversion layer to be separated. Stress is generated between them. In particular, since the stress increases at the corners of the rectangular wavelength conversion layer, damage such as peeling may occur between the wavelength conversion layer and the substrate or between the wavelength conversion layer and the reflective layer. is there.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A wavelength conversion element according to this application example is provided between a substrate, a wavelength conversion layer that emits light having a wavelength different from the wavelength of incident light, and the wavelength conversion layer and the substrate. A wavelength conversion portion having a rectangular shape and a bonding portion for bonding the substrate and the metal layer, the bonding portion being perpendicular to one surface of the substrate. When viewed from one direction, at least a corner portion of the wavelength conversion unit is disposed inside the wavelength conversion unit.

According to this configuration, the wavelength conversion element generates stress between the substrate and the wavelength conversion unit having different coefficients of thermal expansion due to heat generation, but the corners of the wavelength conversion unit are not joined to the substrate. The stress on the corner is relieved. Therefore, breakage of the wavelength conversion unit can be prevented, and the connection state between the substrate and the wavelength conversion unit and the connection state between the metal layer and the wavelength conversion layer in the wavelength conversion unit can be favorably maintained. Therefore, it is possible to provide a wavelength conversion element with improved resistance to stress caused by heat generation.
Moreover, even if the thermal expansion coefficient is a member that is greatly different from the thermal expansion coefficient of the wavelength conversion unit, a member with better heat dissipation can be used as the substrate. Therefore, even if the corner portion of the wavelength conversion portion is not bonded to the substrate, it is possible to provide a wavelength conversion element with good heat dissipation.
Therefore, it is possible to provide a highly reliable wavelength conversion element.

  Application Example 2 In the wavelength conversion element according to the application example described above, it is preferable that the bonding portion is arranged in a circular shape when viewed from the first direction.

According to this configuration, since the joint portion is arranged in a circular shape with respect to the rectangular wavelength conversion portion, the wavelength conversion is performed while ensuring good thermal conductivity between the substrate and the metal layer via the joint portion. In the corner portion of the portion, a configuration in which the joint portion is disposed inside the wavelength conversion portion is possible.
In addition, by using a member obtained by curing a paste-like member as a joint, a circular joint can be easily formed. For example, a substrate is placed so as to spread the paste on the wavelength conversion unit to which an appropriate amount of the paste-like member is supplied on the metal layer, and the paste-like member is cured to easily join the circular shape. The part can be formed. Therefore, it is possible to provide a wavelength conversion element that can realize a configuration in which the bonding portion is disposed inside the wavelength conversion portion at least at the corners of the wavelength conversion portion with easy manufacturing.

  Application Example 3 In the wavelength conversion element according to the application example, it is preferable that the bonding portion is made of metal particles.

  According to this configuration, in the wavelength conversion element, since the joint portion is composed of metal particles, the thermal conductivity between the substrate and the metal layer of the wavelength conversion portion is good. Therefore, it is possible to provide a wavelength conversion element that enables more efficient heat dissipation.

  Application Example 4 A light source device according to this application example includes a light emitting unit that emits excitation light and the wavelength conversion element according to any one of the above.

According to this configuration, the light source device emits light having a wavelength different from the wavelength of the excitation light by the excitation light emitted from the light emitting unit.
And since the light source device is equipped with the wavelength conversion element mentioned above, it becomes possible to emit the light by which the fall of the brightness was controlled over a long period of time.

  Application Example 5 A projection-type device according to this application example projects the light source device described above, a light modulation device that modulates light emitted from the light source device, and light modulated by the light modulation device. And a projection optical device.

  According to this configuration, since the projection type apparatus includes the light source device described above, it is possible to project an image in which a decrease in brightness and occurrence of color unevenness are suppressed over a long period of time.

The schematic diagram which shows the optical system of the projection type apparatus which concerns on this embodiment. The top view which shows typically an example of the wavelength conversion element of this embodiment. The figure which shows typically the cross section of the wavelength conversion element of this embodiment. The top view which shows typically the other example of the wavelength conversion element of this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The projection type apparatus of this embodiment forms an image by modulating light emitted from a light source according to image information, and projects the image onto a screen or the like. In the drawings shown below, the dimensions and ratios of the components are appropriately changed from the actual ones in order to make the components large enough to be recognized on the drawings.

FIG. 1 is a schematic diagram showing an optical system of a projection type apparatus 1 according to this embodiment.
As shown in FIG. 1, the projection type apparatus 1 includes an illumination device 100, a color separation light guide optical system 200, light modulation devices 400 R, 400 G, and 400 B, a cross dichroic prism 500, and a projection optical device 600. Although illustration is omitted, the projection type device 1 includes a control unit that controls the operation of the projection type device 1, a cooling device that cools an internal cooling target, and a power supply device that supplies power to the internal electronic components.

The illumination device 100 includes a first light source device 101, a second light source device 102, a dichroic mirror 103, lens arrays 120 and 130, a polarization conversion element 140, and a superimposing lens 150.
The first light source device 101 includes a light emitting unit 10, a collimating optical system 70, a collimating condensing optical system 90, and a wavelength conversion element 40.

  The light emitting unit 10 includes one or more semiconductor lasers, and emits excitation light E (for example, blue light having a peak wavelength of light emission intensity of about 455 nm). The light emitting unit 10 can also use a semiconductor laser that emits excitation light E having a peak wavelength other than 455 nm.

The collimating optical system 70 includes lenses 71 and 72 and makes the light emitted from the light emitting unit 10 substantially parallel. The collimating optical system 70 may be configured to include one or three or more lenses.
The dichroic mirror 103 is disposed at an angle of 45 ° with respect to the optical axis of the light emitting unit 10, reflects the excitation light E and blue light B described later, and includes yellow light (described later) including red light and green light. It has a function of allowing fluorescence Y) to pass through. The dichroic mirror 103 reflects the excitation light E emitted from the light emitting unit 10 and substantially parallelized by the collimating optical system 70.

  The collimator condensing optical system 90 includes lenses 91 and 92, for example. The collimator condensing optical system 90 has a function of condensing the excitation light E reflected by the dichroic mirror 103 on a wavelength conversion layer 421 (see FIG. 3) described later of the wavelength conversion element 40 and the fluorescence emitted from the wavelength conversion element 40. It has a function of making Y (yellow light) substantially parallel. Note that the collimator condensing optical system 90 may include one or three or more lenses.

As will be described in detail later, the wavelength conversion element 40 includes a substrate 41 and a wavelength conversion unit 42 provided on the substrate 41.
In the wavelength conversion element 40, the phosphor in the wavelength conversion unit 42 is excited by the excitation light E collected by the collimator condensing optical system 90, and emits fluorescence Y having a wavelength different from the wavelength of the excitation light E. The fluorescence Y of the present embodiment is yellow light including red light and green light. For example, the fluorescence Y is light in a wavelength range of about 500 nm to about 700 nm with a peak wavelength Yp of about 540 nm. The fluorescence Y emitted from the wavelength converter 42 is reflected by the metal layer 422 (see FIG. 3) to the collimator condensing optical system 90.

  As shown in FIG. 1, the second light source device 102 is disposed on the opposite side of the dichroic mirror 103 from the collimating optical system 70. The second light source device 102 includes a light emitting unit 710, a condensing optical system 760, a scattering plate 730, and a collimating optical system 770.

  The light emitting unit 710 includes one or more semiconductor lasers and emits blue light B. In addition, the semiconductor laser with which the light emission part 710 is provided can use the same kind as the semiconductor laser with which the light emission part 10 is provided.

  The condensing optical system 760 includes lenses 761 and 762 and substantially condenses the blue light B emitted from the light emitting unit 710 on the scattering plate 730.

  The scattering plate 730 scatters the incident blue light B so as to have a light distribution similar to the light distribution of the fluorescence Y emitted from the wavelength conversion element 40. As the scattering plate 730, for example, polished glass (optical glass) can be used.

The collimating optical system 770 includes lenses 771 and 772 and makes the blue light B from the scattering plate 730 substantially parallel.
The blue light B collimated by the collimating optical system 770 is reflected by the dichroic mirror 103 to the side opposite to the collimating condensing optical system 90.

  The fluorescent light Y emitted from the first light source device 101 is transmitted through the dichroic mirror 103, and is combined with the blue light B emitted from the second light source device 102 and reflected by the dichroic mirror 103 to form white light W as a lens array. 120.

  The lens arrays 120 and 130 and the superimposing lens 150 constitute an integrator optical system. Specifically, the lens array 120 includes a plurality of first small lenses for dividing the white light W from the dichroic mirror 103 into a plurality of partial light beams. The plurality of first small lenses are arranged in a matrix in a plane orthogonal to the optical axis 100ax of the illumination device 100.

The lens array 130 has a plurality of second small lenses corresponding to the plurality of first small lenses of the lens array 120. The lens array 130 forms an image of each first small lens of the lens array 120 together with the superimposing lens 150 in an image forming region of the light modulation devices 400R, 400G, and 400B.
The polarization conversion element 140 aligns random light emitted from the lens array 130 with approximately one type of polarized light that can be used by the light modulation devices 400R, 400G, and 400B.

  The color separation light guide optical system 200 includes dichroic mirrors 210 and 220, reflection mirrors 230, 240 and 250, and relay lenses 260 and 270. The color separation light guide optical system 200 separates the white light W emitted from the illumination device 100 into red light R, green light G, and blue light B, and separates into red light R, green light G, and blue light B, respectively. The light is guided to the corresponding light modulators 400R, 400G, 400B. In addition, field lenses 300R, 300G, and 300B are disposed between the color separation light guide optical system 200 and the light modulation devices 400R, 400G, and 400B.

  The light modulation devices 400R, 400G, and 400B are not shown in detail, but a transmissive liquid crystal panel, an incident-side polarizing plate disposed on the light incident side and a light emitting side of the liquid crystal panel, and an output-side polarizing plate, respectively. It has. Then, the light modulation devices 400R, 400G, and 400B modulate incident color light according to image information to form an image corresponding to each color light.

  The cross dichroic prism 500 has a substantially square shape in plan view in which four right-angle prisms are bonded together, and a dielectric multilayer film is formed on a substantially X-shaped interface in which the right-angle prisms are bonded together. The cross dichroic prism 500 combines the image light of each color light emitted from each of the light modulation devices 400R, 400G, 400B.

  The projection optical device 600 includes a plurality of lenses (not shown), and enlarges and projects the image light combined by the cross dichroic prism 500 as a color image on a screen SCR or the like.

[Configuration of wavelength conversion element]
Here, the wavelength conversion element 40 will be described in detail.
FIG. 2 is a plan view schematically showing an example of the wavelength conversion element 40. FIG. 3 is a diagram schematically illustrating a cross section of the wavelength conversion element 40, and is a diagram illustrating a cross section taken along the line AA in FIG.
As shown in FIGS. 2 and 3, the wavelength conversion element 40 includes a substrate 41, a wavelength conversion unit 42, and a bonding unit 43.

  The substrate 41 is made of a metal such as copper or aluminum having high thermal conductivity, and is formed in a rectangular shape in plan view (for example, a rectangular shape having a side length of about 15 mm). The planar shape of the substrate 41 is not limited to a rectangular shape.

  As shown in FIG. 3, the wavelength conversion unit 42 includes a wavelength conversion layer 421 having a phosphor inside, and a metal layer 422 provided on the substrate 41 side of the wavelength conversion layer 421. The wavelength conversion unit 42 is formed in a rectangular shape in plan view with a size arranged in one surface of the substrate 41 (for example, a rectangular shape having a side length of about 1 mm to 5 mm).

The wavelength conversion layer 421 is formed of a material containing Ce ions such as (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ : Ce, which is a YAG-based phosphor, as an emission center. It has a thickness of about 1/5 to 1/10 of the thickness of 41. Examples of the wavelength conversion layer 421 include ceramic phosphors and materials in which phosphor powder and glass binder are mixed. Note that the wavelength conversion layer 421 is not limited to Ce ions, and a material containing rare earth ions such as Eu, Nd, and Yb may be used.

  The metal layer 422 is formed on one surface of the wavelength conversion layer 421 by vapor deposition or the like. The metal layer 422 has a reflective layer formed of silver, aluminum, or the like, and this reflective layer reflects the fluorescence Y emitted from the wavelength conversion layer 421.

The joint portion 43 is made of metal particles, and joins the substrate 41 and the metal layer 422 in the wavelength conversion portion 42.
The joint portion 43 is formed by sintering from a paste-like member containing silver particles, for example. Specifically, an appropriate amount of the paste-like member serving as the joint portion 43 is supplied to the approximate center on the metal layer 422 using a dispenser or the like. Then, the paste-like member supplied onto the metal layer 422 is pushed and spread by the substrate 41, and is sintered at a high temperature (for example, about 200 to 300 ° C.) to become the joint portion 43.

  As shown in FIGS. 2 and 3, the bonding portion 43 is located inside the wavelength conversion portion 42 at the corner of the wavelength conversion portion 42 when viewed from the direction perpendicular to the one surface of the substrate 41 (first direction). In the side part of the wavelength conversion part 42, it arrange | positions so that it may not jump out of the wavelength conversion part 42.

FIG. 4 is a plan view schematically showing another example of the wavelength conversion element 40.
As shown in FIG. 4, the junction 43 is disposed inside the wavelength conversion unit 42 at the corner of the wavelength conversion unit 42 as viewed from the first direction, and at the side of the wavelength conversion unit 42, the wavelength is It jumps out from the converter 42 and is arranged.
As described above, the bonding portion 43 is disposed inside the wavelength conversion portion 42 at least at the corner portion of the wavelength conversion portion 42 when viewed from the first direction.

  In addition, the bonding portion 43 is naturally spread when the paste-like member supplied onto the metal layer 422 by a dispenser or the like is pushed by the substrate 41, as seen from the first direction, as shown in FIGS. It is arranged in a circle. Here, the circular shape is not limited to a perfect circle, but includes a shape that approximates a circular shape.

  Moreover, the paste-like member has an organic film or the like that covers the surface of the silver particles, and is formed so that the silver particles do not adhere to each other. Therefore, the joint portion 43 formed by sintering the paste-like member becomes a material that does not contain a resin by evaporating the organic film, has nano-order fine pores, and has an arrangement density of silver particles. It becomes uniform. As a result, the bonding portion 43 can improve the heat conduction between the metal layer 422 and the substrate 41. That is, the heat of the wavelength conversion layer 421 that generates heat when the excitation light E is incident can be efficiently transmitted from the joint 43 to the substrate 41 and radiated from the substrate 41. Further, by using a configuration in which a heat sink (not shown) is fixed to the substrate 41 or a configuration in which a fan (not shown) provided in the cooling device blows cooling air to the substrate 41 or the heat sink, a more efficient substrate 41 is provided. Heat dissipation is possible.

  In addition, the metal particle which the junction part 43 has is not limited to silver, Gold, tin, or these metals may be mixed. Further, in order to improve the bonding between the bonding portion 43 and the metal layer 422, the metal layer 422 may have a layer (connection layer) different from the reflection layer on the substrate 41 side of the reflection layer.

Since the wavelength conversion element 40 uses a member that makes the heat dissipation of the substrate 41 good, the thermal expansion coefficient of the substrate 41 is greatly different from the thermal expansion coefficient of the wavelength conversion layer 421. For example, when the substrate 41 is made of copper, the thermal expansion coefficient of the substrate 41 is about 17 × 10 ⁻⁶ / K, which is about the thermal expansion coefficient (about 8 × 10 ⁻⁶ / K) of the wavelength conversion layer 421. Doubled.

  If the thermal expansion coefficient of the substrate 41 and the thermal expansion coefficient of the wavelength conversion layer 421 are greatly different, heat generation generates a gap between the substrate 41 and the wavelength conversion unit 42 and between the wavelength conversion layer 421 and the metal layer 422 in the wavelength conversion unit 42. Stress is generated. In the rectangular wavelength conversion part 42, when all of the wavelength conversion parts are bonded to the substrate as in the conventional wavelength conversion element (not shown), the stress on the corners is particularly large. .

On the other hand, in the wavelength conversion element 40 of the present embodiment, the corners of the wavelength conversion unit 42 are not joined to the substrate 41, and therefore stress generated on the corners of the conventional wavelength conversion element can be relieved.
A temperature cycle test was performed as a stress caused by heat, and the wavelength conversion element 40 of the present embodiment was compared with the wavelength conversion element of the prior art. As a result, in the wavelength conversion element of the prior art, peeling of the wavelength conversion part 42 and peeling between the metal layer 422 and the wavelength conversion layer 421 in the wavelength conversion part 42 occurred, but the wavelength conversion element 40 of the present embodiment. The connection of each component was maintained well.
As described above, in the wavelength conversion element 40, the wavelength conversion section 42 and the substrate 41 are bonded together by the bonding section 43 having good thermal conductivity, and the bonding section 43 is seen from the first direction as the wavelength conversion section 42. At least at the corners, the light is disposed inside the wavelength conversion unit 42.

As described above, according to the present embodiment, the following effects can be obtained.
(1) In the wavelength conversion element 40, since the corner of the wavelength converter 42 is not joined to the substrate 41, stress on the corner due to heat generation is relieved. Therefore, damage to the wavelength conversion unit 42 is prevented, and the connection state between the substrate 41 and the wavelength conversion unit 42 and the connection state between the wavelength conversion layer 421 and the metal layer 422 in the wavelength conversion unit 42 can be favorably maintained. . Therefore, it is possible to provide the wavelength conversion element 40 with improved resistance to stress accompanying heat generation.
Even if the thermal expansion coefficient is a member that is significantly different from the thermal expansion coefficient of the wavelength conversion unit 42, a member with better heat dissipation can be used as the substrate 41. Therefore, even if the corner portion of the wavelength conversion section 42 is not bonded to the substrate 41, it is possible to provide the wavelength conversion element 40 with good heat dissipation.
Therefore, it is possible to provide the wavelength conversion element 40 with high reliability.

(2) The joint portion 43 is arranged in a circle with respect to the rectangular wavelength conversion portion 42. As a result, a configuration in which the bonding portion 43 is disposed inside the wavelength conversion portion 42 at the corner portion of the wavelength conversion portion 42 while ensuring good thermal conductivity between the substrate 41 and the metal layer 422 via the bonding portion 43. Is possible.
Further, the bonding portion 43 is formed by spreading a paste-like member supplied on the metal layer 422 on the substrate 41. Therefore, it is possible to provide the wavelength conversion element 40 that can realize the configuration in which the joint portion 43 is disposed inside the wavelength conversion unit 42 at least at the corners of the wavelength conversion unit 42 with easy manufacturing.

  (3) In the wavelength conversion element 40, since the joint portion 43 is made of metal particles, the thermal conductivity between the substrate 41 and the metal layer 422 of the wavelength conversion portion 42 is good. Therefore, it is possible to provide the wavelength conversion element 40 that enables more efficient heat dissipation.

  (4) Since the corner portion of the wavelength conversion section 42 is not joined to the substrate 41, the wavelength conversion element 40 also has improved resistance to impact such as dropping.

  (5) Since the first light source device 101 includes the wavelength conversion element 40, the first light source device 101 can emit fluorescence Y in which a decrease in luminance is suppressed over a long period of time.

  (6) Since the projection type apparatus 1 includes the first light source device 101, it is possible to project an image in which a decrease in brightness and color unevenness are suppressed over a long period of time.

Note that the present invention is not limited to the above-described embodiment, and various modifications and improvements can be added to the above-described embodiment. A modification will be described below.
Although the projection type device 1 of the embodiment uses a transmissive liquid crystal panel as a light modulation device, a reflection type liquid crystal panel may be used. Further, a micromirror type light modulation device such as a DMD (Digital Micromirror Device) may be used as the light modulation device.

  The light modulation device according to the embodiment employs a so-called three-plate method using three light modulation devices 400R, 400G, and 400B corresponding to red light R, green light G, and blue light B, but is not limited thereto. Alternatively, a single plate method may be adopted, or the present invention can be applied to a projection type device including two or four or more light modulation devices.

  DESCRIPTION OF SYMBOLS 1 ... Projection type | mold apparatus, 10 ... Light emission part, 40 ... Wavelength conversion element, 41 ... Board | substrate, 42 ... Wavelength conversion part, 43 ... Joint part, 101 ... 1st light source device (light source device), 400R, 400G, 400B ... Light modulation device, 421 ... wavelength conversion layer, 422 ... metal layer, 600 ... projection optical device.

Claims (5)

A substrate,
A wavelength conversion layer that emits light having a wavelength different from the wavelength of incident light, a metal layer provided between the wavelength conversion layer and the substrate, and a wavelength conversion unit formed in a rectangular shape;
A bonding portion for bonding the substrate and the metal layer;
With
The wavelength conversion element, wherein the bonding portion is disposed inside the wavelength conversion unit at least at a corner portion of the wavelength conversion unit as viewed from a first direction perpendicular to one surface of the substrate. . The wavelength conversion element according to claim 1,
The wavelength conversion element according to claim 1, wherein the joint portion is arranged in a circular shape when viewed from the first direction. The wavelength conversion element according to claim 1 or 2,
The said junction part is comprised from the metal particle, The wavelength conversion element characterized by the above-mentioned. A light emitting unit that emits excitation light;
The wavelength conversion element according to any one of claims 1 to 3,
A light source device comprising: A light source device according to claim 4;
A light modulation device that modulates light emitted from the light source device;
A projection optical device that projects light modulated by the light modulation device;
A projection type apparatus comprising:

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