JP2019002952A - Wavelength conversion element, light source device, and projection type device - Google Patents

Abstract

To provide a wavelength conversion element that has high reliability.SOLUTION: A wavelength conversion element 40 comprises: a substrate 41; a metal layer 422; a wavelength conversion part 42 that has a wavelength conversion layer 421 on the metal layer 422; a joint part 43 that is formed of metal particles joining the substrate 41 and metal layer 422; and a reinforcement part 44 that covers at least part of the side faces of the wavelength conversion part 42, is arranged to be in contact with the substrate 41, and contains resin.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, a device including a light source and an element that emits light having a wavelength different from the wavelength of the light by light emitted from the light source is known (for example, Patent Document 1).

The light source device described in Patent Document 1 includes a solid light source that emits excitation light, a phosphor layer that is disposed at a position away from the solid light source, emits fluorescence when irradiated with excitation light on the surface, a substrate, and a metal bump Is provided.
The phosphor layer is provided with a reflective layer. A plurality of metal bumps are provided in a predetermined region between the substrate and the reflective layer, and join the reflective layer and the substrate without melting.

JP 2014-137773 A

  However, the light source device described in Patent Document 1 is considered to have good thermal conductivity between the reflective layer and the substrate because the metal bumps are considered to contact the substrate and the reflective layer with dots or lines. Absent. In addition, stress concentrates between the substrate and the phosphor layer having different coefficients of thermal expansion due to heat generation, so that peeling may occur between the reflection layer and the substrate or between the phosphor layer and the reflection layer. There is.

  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 includes a substrate, a metal layer, a wavelength conversion unit having a wavelength conversion layer on the metal layer, and metal particles that join the substrate and the metal layer. And a reinforcing portion including a resin that covers at least a part of the side surface of the wavelength conversion portion and is in contact with the substrate.

According to this configuration, since the wavelength conversion element has the substrate and the metal layer of the wavelength conversion unit bonded to each other by the bonding portion formed of the metal particles, the wavelength conversion layer that generates heat when the excitation light is incident thereon. Heat can be efficiently transferred to the substrate for heat dissipation.
Moreover, since the wavelength conversion element has the reinforcement part in which at least one part of the side surface (end part) of a wavelength conversion part contacts a board | substrate, the tolerance with respect to the stress by heat improves. That is, in the configuration of the prior art that does not have a reinforcing portion, stress concentrates between the substrate and the wavelength conversion layer having different coefficients of thermal expansion as the heat is generated, but the wavelength conversion element of this application example has the stress. Can be dispersed in the reinforcing portion, so that the wavelength conversion portion and the wavelength conversion layer can be prevented from being peeled off. That is, in the wavelength conversion element of this application example, the connection of each component is maintained well. In addition, since it is possible to use a substrate having a coefficient of thermal expansion that is significantly different from the coefficient of thermal expansion of the wavelength conversion layer, it is possible to provide a wavelength conversion element that further improves heat dissipation.
Therefore, it is possible to provide a highly reliable wavelength conversion element with improved resistance to stress caused by heat generation while enabling efficient heat dissipation.

  Application Example 2 In the wavelength conversion element according to the application example, it is preferable that the reinforcing portion is disposed so as to cover the joint portion.

  According to this configuration, the reinforcing portion is connected to the outer periphery of the wavelength conversion portion, that is, all of the end portions of the wavelength conversion portion and the substrate. This makes it possible to provide a wavelength conversion element that further improves resistance to heat stress.

  Application Example 3 In the wavelength conversion element according to the application example described above, it is preferable that the wavelength conversion unit has a rectangular shape in plan view, and the reinforcing unit is in contact with a corner of the wavelength conversion unit.

  According to this structure, the reinforcement part is provided in the corner | angular part of the wavelength conversion part of planar view rectangular shape. Accordingly, the reinforcing portion can be easily formed at the corner portion where stress is more likely to be concentrated by configuring the reinforcing portion to be formed by curing the molten resin. Therefore, it is possible to provide a wavelength conversion element that has effective resistance to heat stress and can be easily manufactured.

  Application Example 4 In the wavelength conversion element according to the application example, it is preferable that the bonding portion is a material that does not include a resin.

  According to this configuration, since the bonding portion is made of a metal particle and is made of a material that does not contain a resin, the thermal conductivity between the substrate and the metal layer of the wavelength conversion portion should be further improved. Can do. Therefore, it is possible to provide a wavelength conversion element that enables more efficient heat dissipation.

  Application Example 5 In the wavelength conversion element according to the application example, it is preferable that the reinforcing portion includes a metal.

  According to this structure, since the reinforcement part contains the metal in addition to resin, it becomes possible to make the elasticity modulus of a reinforcement part close to the elasticity modulus of a junction part. Therefore, it is possible to provide a wavelength conversion element with further improved resistance to heat stress.

  Application Example 6 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, it is possible to provide a light source device that emits fluorescence in which a decrease in luminance is suppressed over a long period of time.

  Application Example 7 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, it is possible to provide a projection type apparatus that projects 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 figure which shows typically the cross section of the wavelength conversion element of this embodiment. The figure which shows typically the plane of the wavelength conversion element of this embodiment. The top view which shows typically the wavelength conversion element of a modification.

  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. 2) 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.

FIG. 2 is a diagram schematically showing a cross section of the wavelength conversion element 40.
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, as shown in FIG.
The wavelength conversion unit 42 includes a wavelength conversion layer 421 having a phosphor inside, and a metal layer 422 provided on the substrate side of the wavelength conversion layer 421.

  In the wavelength conversion element 40, the phosphor in the wavelength conversion layer 421 is excited by the excitation light E condensed 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 conversion unit 42 is reflected by the metal layer 422 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. 3 is a diagram schematically illustrating a plane of the wavelength conversion element 40.
As shown in FIGS. 2 and 3, the wavelength conversion element 40 includes a bonding portion 43 and a reinforcement portion 44 in addition to the substrate 41 and the wavelength conversion portion 42.

  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 described above, the wavelength conversion unit 42 includes the wavelength conversion layer 421 and the metal layer 422, and has a rectangular shape in plan view (for example, a size arranged in one surface (first surface 41A) of the substrate 41 (for example, The length of one side is a rectangle 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 43 is formed, for example, by applying a paste-like member containing silver particles to the substrate 41 or the metal layer 422 and then sintering at a high temperature (for example, about 200 to 300 ° C.). Yes.

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 can be obtained. 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.

The reinforcing portion 44 is formed of, for example, a thermosetting resin such as an epoxy resin, and is provided so as to surround the outer periphery of the rectangular wavelength conversion portion 42 as shown in FIG.
The reinforcing portion 44 is formed by applying a resin to the entire circumference of the side surface (end portion) of the wavelength conversion portion 42 protruding from the first surface 41A of the substrate 41 using a dispenser or the like and then thermosetting. ing. As shown in FIG. 2, the reinforcing portion 44 is connected to the end portion of the wavelength converting portion 42 and the substrate 41 (first surface 41 </ b> A) outside the joint portion 43. Further, the reinforcing portion 44 is disposed so as to cover the joint portion 43.

  Note that the material used as the reinforcing portion 44 is not limited to the epoxy resin, and may be other thermosetting resin, ultraviolet curable resin, or the like as long as the material includes a resin. Further, the material used as the reinforcing portion 44 is more preferably a material having an elastic modulus (for example, an elastic modulus of about 10 GPa) close to the elastic modulus of the joint portion 43 (an elastic modulus of about 15 GPa). A material including particles may be used as the reinforcing portion 44.

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.

  In a conventional wavelength conversion element (not shown) that does not have the reinforcing portion 44, if the thermal expansion coefficient of the substrate 41 and the thermal expansion coefficient of the wavelength conversion layer 421 are greatly different, the substrate 41 and the wavelength conversion portion 42 are generated by heat generation. In the meantime, stress is concentrated between the wavelength conversion layer 421 and the metal layer 422 in the wavelength conversion unit 42.

On the other hand, since the wavelength conversion element 40 of this embodiment has the reinforcement part 44, the stress which generate | occur | produced with the wavelength conversion element of a prior art can be disperse | distributed by this reinforcement part 44. FIG.
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 unit 42 and the substrate 41 are bonded to each other by the bonding unit 43 having good thermal conductivity, and the end of the wavelength conversion unit 42 and the substrate 41 are connected to the reinforcement unit 44. It is connected.

As described above, according to the present embodiment, the following effects can be obtained.
(1) Since the wavelength conversion element 40 includes the bonding portion 43 that favorably conducts heat conduction between the wavelength conversion portion 42 and the substrate 41, the heat of the wavelength conversion layer 421 that generates heat when the excitation light enters. Can be efficiently dissipated.

  (2) The joint portion 43 is made of a metal particle and is made of a material that does not contain a resin. Thereby, the thermal conductivity between the substrate 41 and the metal layer 422 can be further improved. Therefore, it is possible to provide the wavelength conversion element 40 that enables more efficient heat dissipation.

(3) Since the wavelength conversion element 40 includes the reinforcing portion 44, resistance to heat stress is improved.
Since the wavelength conversion element 40 includes the reinforcing portion 44, resistance to impacts such as dropping is improved in addition to resistance to stress caused by heat.
Therefore, it is possible to provide the wavelength conversion element 40 with high reliability.

  (4) 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.

  (5) 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.
In the wavelength conversion element 40 of the embodiment, the reinforcing portion 44 is provided over the entire outer periphery of the wavelength converting portion 42, but the reinforcing portion 44 is in contact with the side surface (end portion) of the wavelength converting portion 42 and the substrate 41. As long as it is arranged so as to cover at least a part of the joint 43.
FIG. 4 is a plan view schematically showing a wavelength conversion element 50 of a modification.
As shown in FIG. 4, in the wavelength conversion element 50 according to the modification, the reinforcing portion 44 is provided at a corner portion of the rectangular wavelength conversion portion 42.
According to this configuration, the reinforcing portion 44 can be easily formed at the corner where stress is more likely to concentrate. Therefore, it is possible to provide the wavelength conversion element 50 that has effective resistance to heat stress and can be easily manufactured.

  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 apparatus, 10 ... Light emission part, 40, 50 ... Wavelength conversion element, 41 ... Board | substrate, 42 ... Wavelength conversion part, 43 ... Joint part, 44 ... Reinforcement 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 (7)

A substrate,
A wavelength conversion unit having a metal layer and a wavelength conversion layer on the metal layer;
A joint composed of metal particles for joining the substrate and the metal layer;
Covering at least a part of the side surface of the wavelength conversion unit, and arranged to come into contact with the substrate, a reinforcing unit including a resin,
A wavelength conversion element comprising: The wavelength conversion element according to claim 1,
The wavelength conversion element, wherein the reinforcing portion is disposed so as to cover the joint portion. The wavelength conversion element according to claim 1,
The wavelength conversion unit has a rectangular shape in plan view,
The wavelength converting element, wherein the reinforcing portion is in contact with a corner portion of the wavelength converting portion. The wavelength conversion element according to any one of claims 1 to 3,
The said junction part is a material which does not contain resin, The wavelength conversion element characterized by the above-mentioned. The wavelength conversion element according to any one of claims 1 to 4,
The wavelength converting element, wherein the reinforcing portion contains a metal. A light emitting unit that emits excitation light;
The wavelength conversion element according to any one of claims 1 to 5,
A light source device comprising: The light source device according to claim 6;
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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