WO2015140854A1

WO2015140854A1 - Wavelength conversion element manufacturing method

Info

Publication number: WO2015140854A1
Application number: PCT/JP2014/005572
Authority: WO
Inventors: 覚河瀬; 梅谷　誠; 千春前田
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2014-03-19
Filing date: 2014-11-05
Publication date: 2015-09-24

Abstract

Provided is a wavelength conversion element manufacturing method that can inhibit changes in the shape of a phosphor. The wavelength conversion element manufacturing method of the disclosure of the present invention includes: coating onto a base a paste obtained by mixing phosphor powder, a glass binder, a resin binder, and a solvent, and thereby forming a paste coating-film; drying the coating film on the base to form a phosphor thin film on the base; pressing the phosphor thin film and firing the pressed phosphor thin film at a temperature which is no more than the softening point of the glass binder to thereby form a phosphor; and bonding the fired phosphor onto a substrate.

Description

Method for manufacturing wavelength conversion element

The present disclosure relates to a wavelength conversion element used in a solid light source projector.

Patent Document 1 discloses a wavelength conversion element having a wavelength conversion member and a heat dissipation member. In Patent Document 1, a mixed powder of glass powder and phosphor powder is placed on a heat radiating member and heated and pressed to form a wavelength conversion member on the heat radiating member, or the mixed powder is pressure-molded and It describes that a wavelength conversion member obtained by firing is bonded onto a heat dissipation member.

JP 2012-185980 A

The present disclosure provides a method of manufacturing a wavelength conversion element that can suppress a change in shape of a phosphor.

In the method for manufacturing a wavelength conversion element according to the present disclosure, a paste obtained by mixing phosphor powder, a glass binder, a resin binder, and a solvent is applied onto a substrate to form a paste coating film, The coating film is dried, a phosphor thin film is formed on the substrate, the phosphor thin film is pressed, and the phosphor thin film after pressing is baked at a temperature below the softening point of the glass binder to form a phosphor. Then, the fired phosphor is bonded onto the substrate.

The method for manufacturing a wavelength conversion element according to the present disclosure is effective for suppressing changes in the shape of the phosphor.

FIG. 1 is a schematic diagram illustrating a configuration example of a light source unit of a solid light source projector. 2 is a plan view and a front view of the phosphor wheel shown in FIG. Drawing 3 is a flowchart showing the manufacturing method of the phosphor wheel concerning an embodiment. FIG. 4 is a diagram for explaining the manufacturing process of the phosphor wheel manufactured by the manufacturing method shown in FIG.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed description than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

In addition, the inventors provide the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and these are intended to limit the subject matter described in the claims. is not.

(Embodiment)
[1. Configuration of light source unit and phosphor wheel]
FIG. 1 is a schematic view showing a configuration example of a light source unit of a solid light source projector, and FIG. 2 is a plan view and a front view of the phosphor wheel shown in FIG.

The light source unit 20 shown in FIG. 1 includes an excitation light source 206, a collimating lens array 207, a dichroic mirror 208, a quarter wavelength plate 209, a condenser lens 210, a phosphor wheel 1, and a condenser lens 211. The wheel 200 and the rod integrator 212 are provided.

The excitation light source 206 is, for example, a blue laser diode that oscillates in the vicinity of a wavelength of about 445 nm, and includes a plurality of laser diodes in order to realize a high-luminance light source device. Excitation light emitted from the excitation light source 206 is converted into parallel light by the collimating lens array 207. The light emitted from the collimating lens array 207 passes through the dichroic mirror 208 and the quarter wavelength plate 209 in order, and is condensed on the phosphor wheel 1 by the condenser lens 210.

The phosphor wheel 1 includes a metal substrate 2, a phosphor 3, and a reflective film 4 as shown in FIG. That is, the phosphor 3 is an example of a wavelength conversion element. The metal substrate 2 is a circular flat plate made of a metal such as aluminum. The phosphor 3 is obtained by sintering phosphor powder and a binder into a thin film, and converts excitation light emitted from the excitation light source 206 into fluorescence. In the example of FIG. 2A, the phosphor 3 is formed in four parts in the circumferential direction of the metal substrate 2, but the purpose is to improve manufacturing efficiency in the manufacturing process of the phosphor 3. . Therefore, the shape of the phosphor 3 provided on the metal substrate 2 is not particularly limited and may be arbitrary. Further, when the phosphor 3 is divided and formed as shown in FIG. 2A, the wavelength conversion characteristics of the divided phosphors 3 can be made different. The reflective film 4 is provided in order to reflect the light transmitted through the phosphor 3 and improve the light extraction efficiency from the phosphor 3. The phosphor wheel 1 is connected to a rotation mechanism (not shown) and is rotated at a predetermined rotation speed.

Fluorescence emitted from the phosphor wheel 1 passes through the condenser lens 210 and the quarter wavelength plate 209 in order, and then is reflected by the dichroic mirror 208 in the direction of the condenser lens 211. The light reflected by the dichroic mirror 208 is collected by the condenser lens 211, passes through a dichroic filter (not shown) provided on the wheel 200, and enters the incident end face of the rod integrator 212. From the exit end face of the rod integrator 213, light having a uniform illuminance distribution is emitted, and the emitted light is used as illumination light.

[2. Method for manufacturing phosphor wheel]
Hereinafter, the manufacturing method of the phosphor wheel 1 described above will be described with reference to FIGS.

FIG. 3 is a process diagram showing a method for manufacturing a phosphor wheel according to the embodiment, and FIG. 4 is a diagram for explaining a manufacturing process of the phosphor wheel manufactured by the manufacturing method shown in FIG.

<Adjustment of paste>
First, in step S1 of FIG. 3, a phosphor powder, a glass binder, a resin binder, and a solvent are mixed to produce a phosphor powder paste.

The phosphor powder is selected according to the wavelength of the excitation light and the necessary fluorescence wavelength. Examples of the phosphor powder include oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, acid chloride phosphors, sulfide phosphors, oxysulfide phosphors, and halide phosphors. One kind or a mixture of two or more kinds of chalcogenide phosphors, aluminate phosphors, halophosphate phosphors, YAG compound phosphors and the like can be used.

The glass binder is for holding the shape of the phosphor 3 after the baking step (step S7 in FIG. 3) described later.

The resin binder (organic binder) has the formability of the coating film of the paste in the paste application process (step S2 in FIG. 3) described later and the form retention of the phosphor thin film obtained after the drying process (step S3 in FIG. 3). It is for improving. Moreover, in the press process (step S4 of FIG. 3) mentioned later, when laminating | stacking and pressing a some phosphor thin film, the resin binder also has a role which improves the lamination | stacking property of each phosphor thin film. Examples of the resin binder include acrylic resins made of acrylic acid esters, methacrylic acid ester polymers or copolymers, polyvinyl alcohol (PVA), polypropylene carbonate resins, cellulose resins such as ethyl cellulose, and polymethyl methacrylate (PMM) resins. Can be used. As the resin binder, it is preferable to use a material that decomposes or volatilizes in a firing temperature range of a firing step described later.

Examples of the solvent include ethyl acetate, butyl acetate, 2-butanol, methyl ethyl ketone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, butyl carbitol (diethylene glycol monobutyl ether), butyl carbitol acetate, terpineol, and terpineol. One kind or a mixture of two or more kinds of pinenol acetate, dihydroterpineol, dihydroterpineol acetate, texanol and the like can be used.

) A plasticizer may be further added to the paste. As will be described later, in the manufacturing method according to the present embodiment, a phosphor having a desired thickness can be obtained by laminating a plurality of dried phosphor thin films and pressing the phosphor thin film. Since the surface of the layer is not dried, the adhesion of the laminated phosphor thin films can be improved. Since the plasticizer contained in the phosphor thin film is decomposed or volatilized in the firing step described later, there is no problem caused by the use of the plasticizer in the completed phosphor 3. As the plasticizer, for example, a phthalate ester can be suitably used.

The paste is prepared by adding the constituent components of the paste to a solvent and mixing them using various mixers such as a planetary mixer, a ball mill, a blender mill, and a three roll.

<Application process>
Next, in step S2 of FIG. 3, the paste of the phosphor powder and the binder is applied on the base material 10 to form the paste coating film 11 (see FIGS. 4A and 4B).

As the substrate 10, a resin film having releasability from the phosphor thin film 12 (FIG. 4C) obtained after drying the paste coating film 11 can be used. Materials for the substrate 10 include polyester resins such as polyethylene terephthalate (PET) / polybutylene terephthalate-isophthalate copolymer, polyolefin resins such as polyethylene / polypropylene / polymethylpentene, polyfluorinated ethylene resins, cellulose resins, and acrylic resins. Polyamide resin such as polyimide resin and nylon, polycarbonate resin, polyacetate resin, polyphenylene sulfide resin, cellophane and the like can be used. Moreover, in order to improve the peelability of the phosphor layer after drying, a release treatment such as providing a release layer made of a fluororesin or a silicone resin may be performed on the surface of the substrate.

Application of the paste to the substrate 10 can be performed using a doctor blade, a reverse roll coater, or the like.

<Drying process>
Next, in step S <b> 3 of FIG. 3, the paste coating film 11 formed on the substrate 10 is dried to obtain the phosphor thin film 12. The main purpose of this drying step is to volatilize the solvent contained in the coating film 11 in order to solidify the coating film 11 of the paste. Therefore, the drying temperature can be appropriately set according to the solvent used.

<Pressing process>
Next, in step S4 of FIG. 3, the phosphor thin film 12 formed on the base 10 is pressed to obtain an unsintered phosphor 13. By pressing the phosphor thin film 12 at a stage before firing, it is possible to suppress changes in shape such as warpage of the phosphor 3 in the firing process.

In this pressing step, the plurality of phosphor thin films 12 can be integrated by overlapping and pressing the plurality of phosphor thin films 12. When the phosphor thin film 12 is formed by applying and drying the paste on the base material 10, it is possible to form a film while maintaining the uniformity of the film thickness in the application process, depending on the properties such as the viscosity of the paste used. There is a limit to the thickness of the film 11. That is, there is an upper limit to the thickness of the phosphor 3 that can be formed by the phosphor thin film 12 obtained by applying the paste once.

Therefore, as shown in FIGS. 4C to 4E, a plurality of phosphor layers are stacked and pressed to obtain an unsintered phosphor 13 (phosphor thin film after pressing) having a desired thickness. Can do. For example, when two layers of the phosphor thin film 12 are laminated, first, as shown in FIG. 4C, the phosphor thin films 12 are in contact with a pair of base materials 10 having the phosphor thin film 12 formed on the surface. Overlapping so that. Next, as shown in FIG. 4 (d), the two layers of the phosphor thin film 12 are pressed in a state of being sandwiched between the base materials 10, whereby the two layers of the phosphor thin film 12 are in close contact and integrated. The phosphor 13 can be obtained. When three or more layers of phosphor thin films 12 are laminated, one substrate 10 is peeled off from the state of FIG. 4 (e), and another phosphor thin film 12 formed on the substrate 10 is further laminated. Pressing may be performed again, or as shown by a solid line in FIG. 4 (c), between the pair of facing phosphor thin films 12, one or more phosphor thin films 12 from which the substrate 10 has been peeled are sandwiched and pressed. May be. As described above, the main purpose of this pressing step is to suppress changes in the shape of the phosphor such as warpage of the phosphor in the firing step. Therefore, the pressing step is performed even when two or more phosphor thin films 12 are not laminated. That is, when laminating a plurality of phosphor thin films 12, a plurality of phosphor thin films 12 can be integrated by performing a pressing process for suppressing a change in the shape of the phosphor in the firing process. It can be said that a separate process for laminating the layers can be omitted.

<Base material peeling and die cutting process>
Next, in step S5 of FIG. 3, the base material 10 is peeled from the unfired phosphor 13 obtained by pressing. In step S6 of FIG. 3, the unfired phosphor 13 after the base material 10 is peeled is desired. (See FIG. 4F).

<Baking process>
Next, in step S7 of FIG. 3, the green phosphor 13 after die cutting is fired to obtain the phosphor 3 (see FIG. 4G). Baking step is carried out at the softening point of the glass binder used (T _S) or lower. By performing baking at a temperature equal to or lower than the softening point of the glass binder, it is possible to suppress a change in shape such as warpage in the phosphor 3 during the baking process. More specifically, the firing temperature is in the range of (T _S −25) to (T _S −5) ° C. By baking in this temperature range, a glass matrix can be formed while suppressing changes in the shape of the phosphor. When firing is performed at a temperature exceeding the softening point of the glass binder, there is a possibility that a shape change such as warpage occurs in the phosphor 3. In the firing step, the resin binder and solvent contained in the unfired phosphor 13 and the plasticizer added as necessary are almost lost by decomposition or volatilization.

<Reflective film formation process>
Next, in step S8 of FIG. 3, the reflective film 4 is formed on one surface of the phosphor 3 after firing (see FIG. 4 (h)). The reflective film 4 is made of a metal thin film such as aluminum, silver, gold, palladium, or titanium. The reflective film 4 may be formed by vapor deposition or sputtering, or may be formed by applying a paste or liquid containing metal fine particles or an organometallic compound to one surface of the phosphor 3 and then baking. When the reflective film 4 is formed by applying paste or liquid, the paste or liquid is applied to the phosphor before firing, and the reflective film 4 is formed simultaneously with the firing of the phosphor by firing once in the firing process. Alternatively, the reflective film 4 may be formed by applying a paste or liquid to the fired phosphor and firing again. When baking for forming the reflective film 4 after the baking process of the phosphor 3 is performed, the baking is performed at a temperature lower than the baking temperature of step S7 in FIG.

<Phosphor bonding process>
Next, in step S <b> 9 in FIG. 3, the phosphor wheel 1 is obtained by bonding the phosphor 3 after the reflection film 4 is formed to the surface of the metal substrate 2. The method for bonding the phosphor 3 to the metal substrate 2 is not particularly limited, and the surface on the side where the reflective film 4 is formed can be bonded to the metal substrate 2 via an adhesive or solder. In the case of joining with solder, it is more preferable to use solder because it is superior to an adhesive in terms of heat resistance and thermal conductivity.

[3. Effect]
In the method for manufacturing a phosphor wheel according to the present embodiment, the phosphor layer is pressed before the firing step, and firing is performed at a temperature equal to or lower than the softening point of the glass, thereby suppressing the shape change of the phosphor. .

Further, in the method for manufacturing the phosphor wheel according to the present embodiment, the phosphor powder and the binder are not mixed, molded and fired as they are, but the phosphor powder and the binder are pasted with a solvent to form a substrate. It is applied on top. When the phosphor powder and the binder are mixed as they are, the dispersion of the phosphor powder and the binder is not uniform, and the function as a binder by the glass binder is not sufficiently exhibited. It may lead to decline. On the other hand, in the manufacturing method according to the present embodiment, the phosphor powder and the binder can be uniformly dispersed by pasting the phosphor powder and the binder, so that the phosphor has a sufficient strength after firing. As well as a decrease in luminous efficiency due to non-uniform dispersion of the phosphor powder.

In the method for manufacturing a phosphor wheel according to the present embodiment, a resin binder is used to maintain the shape of the paste coating film and the unfired phosphor. However, the resin binder decomposes or volatilizes in the firing step and fires. Thereafter, the binder of the phosphor 3 is formed with a glass binder. The phosphor 3 formed with a glass binder is superior in heat resistance as compared with a phosphor formed with a resin binder. Therefore, the intensity of the generated fluorescence can be improved by increasing the output of the excitation light source (laser) that irradiates the phosphor 3 with excitation light. Moreover, the fluorescent substance 3 formed with the glass binder is excellent also in heat dissipation compared with the fluorescent substance formed with the resin binder. It is known that phosphor molecules are quenched by excessive temperature rise, but the phosphor 3 obtained by the manufacturing method according to the present embodiment is formed of a glass binder, so that heat dissipation is improved. Even if the output of the light source is increased, temperature quenching can be suppressed. Therefore, the phosphor wheel 1 obtained by the manufacturing method according to the present embodiment can suppress the temperature quenching even if the output of the excitation light source is increased, so that the conversion efficiency from excitation light to fluorescence can be improved. . Moreover, according to the phosphor wheel 1 obtained by the manufacturing method according to the present embodiment, the intensity of the fluorescence generated by increasing the output of the excitation light source can be increased, so that the diameter of the phosphor wheel 1 can be reduced. It becomes possible. By reducing the diameter of the phosphor wheel 1, the entire light source unit 20 can be downsized. Moreover, since the heat resistance and thermal conductivity of the phosphor wheel 1 are improved, there is an advantage that the cooling system of the light source unit 20 can be simplified.

Further, in the method for manufacturing the phosphor wheel 1 according to the present embodiment, since the metal substrate 2 is used as the wheel substrate, the heat dissipation of the entire phosphor wheel 1 obtained can be improved. In addition, the metal substrate 2 has an advantage that it is less likely to be damaged than a ceramic substrate or a glass substrate.

Furthermore, in the manufacturing method of the phosphor wheel 1 according to the present embodiment, a method of joining the fired phosphor 3 to the metal substrate 2 is adopted. When the metal substrate 2 is used as the substrate of the phosphor wheel 1 and the glass binder (inorganic binder) is used as the binder of the phosphor powder as in the present embodiment, the phosphor powder mixture layer is directly provided on the metal substrate 2. When firing is performed, deformation such as warpage may occur in the metal substrate 2 during the cooling process from the firing temperature to room temperature. In addition, since the thermal expansion coefficient of the glass binder is smaller than the thermal expansion coefficient of the metal substrate 2, the shrinkage of the metal substrate 2 in the cooling process is relatively larger than that of the phosphor 3 after firing, Shape defects such as cracks and peeling from the metal substrate 2 are likely to occur. Even in the case where the phosphor wheel 1 is configured using the metal substrate 2 and the glass binder as in the present embodiment, the thermal expansion characteristics of the material can be used as long as the phosphor 3 after firing is bonded to the metal substrate 2. These shape defects due to the difference can be eliminated.

(Other embodiments)
In the above-described embodiment, the phosphor thin film 12 formed by applying the paste on the substrate 10 has been described as being punched into a desired shape after pressing, but has a desired planar shape in advance by a printing method or the like. The coating film 11 may be formed on the substrate 10. In this case, the above-described die cutting process can be omitted.

Hereinafter, examples in which the embodiment of the present invention is specifically implemented will be described. However, the present invention is not limited to the following examples.

First, 10 parts by weight of a glass binder (softening point T _S : 580 ° C., glass transition point T _G : 490 ° C.), 10 parts by weight of an acrylic resin binder, and 20 parts by weight of a solvent (100 parts by weight of the phosphor powder) 10 parts by weight of butyl carbitol and 10 parts by weight of propylene glycol monomethyl ether acetate) and 5 parts by weight of bisbutylbenzyl phthalate as a plasticizer were mixed using a mixer to paste the phosphor powder.

Next, the prepared paste was applied to a PET film (thickness 38 μm) having a release treatment on one side, and the coating film was dried.

Next, the dried coating film was pressed at a pressure of 500 kgf / cm ² (49.05 MPa) for 10 seconds.

Thereafter, the PET film was peeled from the pressed phosphor thin film, and the phosphor thin film was punched into the shape shown in FIG. Firing was performed for 240 minutes at 575 ° C. or lower, which is lower than 580 ° C., which is the softening point of the glass binder.

When the phosphor obtained through the above steps was visually confirmed, no shape change such as warping was observed.

As described above, the embodiments have been described as examples of the technology in the present disclosure. For this purpose, the accompanying drawings and detailed description are provided.

Accordingly, among the components described in the accompanying drawings and the detailed description, not only the components essential for solving the problem, but also the components not essential for solving the problem in order to illustrate the above technique. May also be included. Therefore, it should not be immediately recognized that these non-essential components are essential as those non-essential components are described in the accompanying drawings and detailed description.

In addition, since the above-described embodiments are for illustrating the technique in the present disclosure, various modifications, replacements, additions, omissions, and the like can be made within the scope of the claims and the equivalents thereof.

The present disclosure is applicable to a phosphor used for a wavelength conversion element such as a solid light source projector.

DESCRIPTION OF SYMBOLS 1 Phosphor wheel 2 Metal substrate 3 Phosphor 4 Reflective film 10 Base material 11 Coating film 12 Phosphor thin film 13 Unsintered phosphor

Claims

A method of manufacturing a wavelength conversion element in which a phosphor is provided on a substrate,
Applying a paste obtained by mixing phosphor powder, glass binder, resin binder and solvent on a substrate to form a coating film of the paste,
Drying the coating film on the substrate to form a phosphor thin film on the substrate;
Pressing the phosphor thin film;
Firing the phosphor thin film after pressing at a temperature below the softening point of the glass binder to form the phosphor,
A method for manufacturing a wavelength conversion element, wherein the phosphor after firing is bonded onto the substrate.
The method for manufacturing a wavelength conversion element according to claim 1, wherein a plurality of phosphor layers are stacked and pressed when the phosphor layer is pressed.
A reflective film is formed on one surface of the phosphor after firing,
The method for manufacturing a wavelength conversion element according to claim 1, wherein one surface of the phosphor on which the reflective film is formed is bonded to the substrate.