JP2021015133A - Light source device and projection device - Google Patents

Abstract

To provide a light source device and a projection device that can emit light of which red component has been made more intense.SOLUTION: A light source device 100 is for drawing red components, and includes: an excitation light source 110 for emitting a blue laser as an excitation light; and a wavelength conversion plate 150 having a phosphor layer containing YAG:Ce phosphor particles and ruby phosphor particles, the wavelength conversion plate receiving the emitted excitation light and emitting a wavelength band light. It thus becomes possible to cause the ruby phosphor particles to emit light by light emission of the YAG:Ce phosphor particles and to emit light of which red component has been made more intense.SELECTED DRAWING: Figure 1

Description

The present invention relates to a light source device and a projection device for extracting a red component.

Conventionally, a phosphor that emits light by irradiation with a laser beam has been used for a projector or the like. For example, the garnet material described in Patent Document 1 is composed of a garnet having a composition represented by the chemical formula A _3-x B ₅ O ₁₂ : D _x containing a barium-containing oxide. A is selected from rare earth metals such as lutetium and yttrium or mixtures thereof, and B is selected from aluminum and the like or mixtures thereof. D is a dopant selected from chromium and the like, and x exists in the range of 0 ≦ x ≦ 2.

On the other hand, the red component of an image produced by a laser projector is often realized by passing light emitted from a device whose wavelength is converted by laser light excitation, such as a phosphor wheel, through a red filter. For example, the apparatus described in Patent Document 2 includes a phosphor wheel that generates a part of the illumination light and a color filter unit having a red filter that selectively transmits red light in the illumination light. There is.

Japanese Patent Application Laid-Open No. 2013-533359 Japanese Unexamined Patent Publication No. 2008-268639

However, the method using the red filter as described above tends to lack the intensity of the red component. Therefore, there is a strong demand for improvements to brighten the image. Red phosphor CaAlSiN ₃ used in LEDs; Eu ²⁺ (hereinafter abbreviated as CASN) and yellow phosphor Y ₃ Al ₅ O ₁₂ : Ce ³⁺ (hereinafter YAG: Ce) often used in current phosphor wheels. In combination with the red filter, the dependence of the emission intensity on the laser beam density can be represented in a graph.

FIG. 16 is a graph showing the relationship between the laser light output density of CASN and YAG: Ce and the emission intensity. The emission intensity of CASN is high when the laser light density is low, but saturates when the laser light density is high. Since a laser projector excites fluorescence at a laser light density of at least 100 W / cm ² , at present, there is no choice but to use a red filter together with YAG: Ce. However, the lack of strength of the red component is still a bottleneck in the entire product system.

When the irradiation density becomes high, as shown in FIG. 16, a defect generally called "luminance saturation" is observed. It can be inferred that the so-called "temperature quenching", in which the luminous efficiency decreases as the temperature of the phosphor screen rises, is also involved in this. Fluorescent materials capable of achieving high-luminance red color, such as CASN and YAG: Ce, have been studied, but there is no effective measure at present.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a light source device and a projection device capable of irradiating light having an improved intensity of a red component.

In order to achieve the above object, the following measures are taken in the present invention. That is, the light source device of the present invention is a light source device that extracts a red component, and has an excitation light source that irradiates a blue laser as excitation light, and a phosphor layer containing YAG: Ce phosphor particles and ruby phosphor particles. A wavelength conversion plate that receives the irradiated excitation light and emits wavelength band light.

According to the present invention, the ruby phosphor particles can be made to emit light through the light emission of the YAG: Ce phosphor particles, and the light with improved intensity of the red component can be irradiated.

It is a schematic diagram which shows the structure of the light source apparatus which concerns on 1st Embodiment. It is sectional drawing which shows the structure of an example of the wavelength conversion plate which concerns on 2nd Embodiment. It is sectional drawing which shows the structure of the wavelength conversion plate which concerns on 3rd Embodiment. It is a schematic diagram which shows the structure of the light source apparatus which concerns on 4th Embodiment. It is a front view which shows the structure of the wavelength conversion plate which concerns on 4th Embodiment. It is a schematic diagram which shows the structure of the projection apparatus which concerns on 5th Embodiment. It is a table which shows the material and composition of a ruby sample. It is a graph which shows the relationship between the Cr concentration of a ruby sample and the emission intensity. It is a graph which shows the spectrum of the excitation and emission of ruby. It is a graph which shows the emission spectrum of a fluorescent substance layer sample, and the spectral transmittance of a red filter. YAG: It is a graph which shows the relationship between the mixing ratio of Ce phosphor particles and ruby phosphor particles, and the amount of red light emission. YAG: FIG. 3 is a graph showing the relationship between the mixing ratio of Ce phosphor particles and ruby phosphor particles and the red color tone. It is a graph which shows the relationship between the average particle diameter of a phosphor particle and the amount of red light emission. It is a graph which shows the relationship between the structure of a phosphor layer and the amount of red light emission. It is a graph which shows the relationship between the presence or absence of ruby of a phosphor layer, and white brightness. It is a graph which shows the relationship between the laser light output density of CASN and YAG: Ce, and the light emission intensity.

Next, an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
(Overall configuration of light source device)
FIG. 1 is a schematic view showing the configuration of the light source device 100. The light source device 100 includes an excitation light source 110, optical lenses 120 and 140, a dichroic filter 130, a wavelength conversion plate 150 and a red filter 160, and irradiates the wavelength conversion plate 150 with excitation light to extract fluorescence emission.

(Excitation light source)
The excitation light source 110 irradiates a blue laser as excitation light. As the excitation light source 110, a blue light source that excites phosphor particles such as YAG and LuAG, for example, a blue laser diode (LD) can be used. The light source device 100 is particularly suitable for extracting a red component.

The power density of the excitation light in use is more preferred if the it is preferably 100W / cm ² or more and 70 W / cm ² or more. As described above, it is possible to maintain high light extraction efficiency while irradiating high-intensity fluorescence by irradiating excitation light having a high output density. Examples of the light source device 100 in which such excitation light is used include a projection device as described below.

(Wavelength conversion plate)
In the wavelength conversion plate 150, a phosphor layer 155 is formed by a coating film in which a binder and phosphor particles are mixed on a metal substrate 152 having excellent thermal conductivity such as Al or Cu. Further, in order to increase the fluorescence emission intensity, it is desirable that the substrate 152 is coated with a highly reflective film of Ag or Al. The wavelength conversion plate 150 has a phosphor layer 155 and receives the irradiated excitation light to emit wavelength band light.

The phosphor layer 155 contains phosphor particles, and the phosphor particles emit light in a predetermined wavelength band by excitation. The phosphor particles include YAG: Ce (Y ₃ Al ₅ O ₁₂ : Ce ³⁺ ) phosphor particles and ruby (Al ₂ O ₃ : Cr ³⁺ ) phosphor particles. As a result, the ruby phosphor particles can be made to emit light through the light emission of the YAG: Ce phosphor particles, and light with improved intensity of the red component can be irradiated. Ruby is a trace amount of Cr ³⁺ introduced into Al ₂ O ₃ crystals. As will be described later, the Cr concentration in the ruby phosphor particles is preferably 0.005 or more and 0.013 or less as the composition ratio with respect to Al, and is particularly preferably around 0.010.

Such a wavelength conversion plate 150 is applied to a device represented by a laser projector. In applications involving high density laser excitation, the wavelength converter 150 is used in combination with a red filter.

The ratio of the weight of the ruby phosphor particles contained in the phosphor layer 155 to the weight of the YAG: Ce phosphor particles is preferably 0.2 or more and 4.8 or less. As a result, it is possible to irradiate light having a high degree of redness with sufficient intensity.

The average particle size of the ruby phosphor particles is several μm or more and ten and several μm or less. The ruby phosphor particles are preferably 0.005 ≦ x ≦ 0.015 when the composition is expressed as (Al _1-x Cr _x ) ₂ O ₃ . As a result, the emission intensity of the ruby phosphor particles can be increased.

The wavelength conversion plate 150 can be manufactured as follows. First, the substrate 152 is prepared, and a phosphor paste in which fluorescent particles are dispersed in an organic binder or an inorganic binder is prepared. A phosphor paste is applied to a portion of the substrate 152 that is irradiated with the excitation light. Any method may be used for applying the phosphor paste, and for example, a drawing method using a dispenser (liquid quantitative discharge device), a screen printing method, a spray method, an inkjet method, or the like can be used. Then, the substrate 152 coated with the paste is fired or dried to form the phosphor layer 155.

(Red filter)
The red filter is a filter for extracting a red component. The red filter is formed so as to transmit only the red wavelength region light of the irradiated light and reflect the other wavelength region light. The same applies when the red filter is replaced with a filter of another color. The green filter transmits only green wavelength light, and the blue filter transmits only blue wavelength light.

[Second Embodiment]
It is preferable that the average particle size of the ruby phosphor particles is larger than the average particle size of the YAG: Ce phosphor particles, and the YAG: Ce phosphor particles are unevenly distributed toward the side receiving the excitation light of the phosphor layer. .. With such a configuration, the excitation light can be incident from the side where the distribution of the YAG: Ce phosphor particles is large, and the ruby phosphor particles can be efficiently emitted by the fluorescence generated thereby.

FIG. 2 is a cross-sectional view showing an example of the configuration of the wavelength conversion plate 150. As shown in FIG. 2, in the phosphor layer 155, the ruby phosphor particles 155b are larger than the YAG: Ce phosphor particles 155a, and the ruby phosphor particles 155b are preferably present at a higher density on the substrate side. .. Due to this structure, the YAG: Ce phosphor particles 155a, which are close to the blue laser excitation source, emit light with high efficiency, and among the isotropically spread emission, the emission toward the substrate side excites the ruby phosphor particles 155b.

The density of the YAG: Ce phosphor particles 155a is about 4.6 g / cm ³ , whereas the density of the ruby phosphor particles 155 b is about 4.0 g / cm ³ . Therefore, even if powders having the same particle size are simply mixed and coated on the substrate 152, the dense YAG: Ce phosphor particles 155a settle first and are present in a large amount in the layer close to the substrate 152. On the other hand, the ruby phosphor particles 155b are abundantly present in the region near the surface of the phosphor layer 155. The ruby phosphor particles 155b have low light absorption in the blue region. Therefore, it is effective to form a layer close to the blue laser excitation source with YAG: Ce phosphor particles 155a at a high density and to form a lower layer with ruby phosphor particles 155b. The ruby phosphor particles 155b can be excited by the light emission of the YAG: Ce phosphor particles 155a. The wavelength conversion plate 150 is a reflection type, but the same applies even if it is a transmission type. For example, when the excitation light is incident from the substrate side, it is preferable to adjust so that the YAG: Ce phosphor particles are distributed on the substrate side.

[Third Embodiment]
In the above embodiment, the YAG: Ce phosphor particles 155a and the ruby phosphor particles 155b are mixed to form the phosphor layer 155, although the distribution is biased. On the other hand, the YAG: Ce phosphor particles 155a and the ruby phosphor particles 155b may be completely separated to form a layer.

FIG. 3 is a cross-sectional view showing the configuration of the wavelength conversion plate 250 having a layer-separated structure. In the phosphor layer 255 of the wavelength conversion plate 250, the YAG: Ce phosphor layer 256 containing YAG: Ce phosphor particles and the ruby phosphor layer 257 containing ruby phosphor particles are laminated, and the phosphor layer 255 is laminated. It is preferable that the YAG: Ce phosphor layer 256 having high light emission efficiency is arranged on the blue laser light receiving side, which is the excitation source. Therefore, the ruby phosphor layer 257 is arranged on the substrate 252 side.

With such a configuration, the excitation light is incident on the ruby phosphor layer 257 from the YAG: Ce phosphor layer 256 side, and the ruby phosphor layer 257 can be efficiently emitted by the fluorescence generated thereby.

In such a wavelength conversion plate 250, first, ruby phosphor particles mixed with a binder are applied onto the substrate 252, and then YAG: Ce phosphor particles are laminated. In this case, even if the particle size of the ruby phosphor particles is small, they can be reliably arranged in the lower layer (the substrate 252 side) of the YAG: Ce phosphor layer 256.

[Fourth Embodiment]
The wavelength conversion plate of the above embodiment is preferably configured as a phosphor wheel. The phosphor wheel is provided with a phosphor layer as a red component extraction portion in the circumferential direction, and is configured to be capable of multicolor emission by being divided into a plurality of segments in the circumferential direction, with respect to the irradiation position of the excitation light. It is rotatable. Thereby, the white emission intensity can be improved. Then, the rotation of the phosphor wheel can prevent overheating due to the irradiation of the excitation light.

FIG. 4 is a schematic view showing the configuration of the light source device 300 using the phosphor wheel 350. The light source device 300 has a configuration in which the wavelength conversion plate 150 is replaced with the fluorescent device 370 based on the configuration shown in FIG. The fluorescent device 370 includes a phosphor wheel 350 (wavelength conversion plate) and a drive unit 360 (motor), and is used as, for example, a fluorescent light emitting element for a projector. The drive unit 360 rotatably holds the phosphor wheel 350 via the shaft.

FIG. 5 is a front view showing the configuration of the phosphor wheel 350 as a wavelength conversion plate. The phosphor wheel 350 includes a substrate 352 and a phosphor layer 355, and is driven by high-speed rotation (for example, 7200 rpm) to alleviate a local temperature rise of the phosphor screen due to high-density laser excitation. The substrate 352 is formed as, for example, a disk-shaped rotating body of a metal (Al or Cu) having excellent thermal conductivity. The phosphor layer 355 is formed on the circumference of the substrate 352. It is desirable that a highly reflective film of Ag or Al is coated on the surface of the substrate 352 of the phosphor wheel 350 on the side where the phosphor layer 355 is provided in order to increase the fluorescence emission intensity.

The phosphor layer 355 includes a red component extraction section 355a, a yellow component extraction section 355b, a green component extraction section 355c, and a blue component extraction section 355d. In the red component extraction unit 355a, for example, a mixture of YAG: Ce phosphor particles and ruby phosphor particles at a weight ratio of 2: 1 is used as the phosphor particles, and the phosphor layer 355 is formed. .. The yellow component extraction portion 355b is provided on the substrate 352 by YAG: Ce phosphor particles. The green component extraction unit 355c is provided on the substrate 352 by Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ (abbreviated as LuAG: Ce) phosphor particles.

Each portion can be formed by coating a mixture of the applicable phosphor particles and the silicone resin with a liquid quantitative discharge device. It is preferable that the film thickness of the central portion of the band on the arc is formed so as to have a predetermined thickness (for example, 200 μm) in each phosphor layer. The blue component extraction unit 355d is formed of a glass plate and transmits a blue laser which is excitation light. This transmitted light is used as a blue component of the image.

The phosphor wheel 350 can be manufactured basically in the same manner as the wavelength conversion plate. First, a wheel substrate formed in a disk shape is prepared, and a plurality of types of phosphor pastes are prepared. Then, a phosphor paste that produces different fluorescence is separately applied to the portion of the wheel substrate that is irradiated with the excitation light. The wheel substrate coated with the paste in this manner is fired or dried to form a phosphor layer.

[Fifth Embodiment]
The projection device may be configured by using the light source device of the above embodiment. Images displayed by a projection device such as a projector are easily affected by external light, and high illuminance is required to obtain a high-quality display. In order to project with high illuminance, it is necessary to increase the amount of light from the light source, and it is preferable to use a light source device that combines high-density excitation light and a phosphor layer that suppresses quenching. By using the light source device of the above embodiment, the projected illuminance can be maintained high, and a good projected image can be obtained even in an environment with external light.

FIG. 6 is a schematic view showing the configuration of the projection device 400 (projector). The projection device 400 includes an input unit 410, a sensor 420, a control unit 430, a light source device 300, a light guide optical system 440, a display element 460 (DMD), a projection optical system 470, and a control unit 430.

The input unit 410 receives the input of the data of the image to be projected, and delivers the input data to the control unit 430. The input unit 410 may receive data from a device other than the projection device 400, or may be connected to the Internet or the like and receive data by communication. The input unit 410 may accept the user's input. The sensor 420 detects the rotational position of the phosphor wheel 350.

The control unit 430 controls the output of the excitation light from the excitation light source 310 according to the rotation position of the phosphor wheel 350 with respect to the input of the intensity of the projected light. By controlling the excitation light, the intensity of the light emitted by the phosphor wheel 350 can be arbitrarily changed.

Further, by controlling the output of the excitation light according to the gradation of color and brightness, deterioration of the excitation light source 310 and the phosphor wheel 350 can be suppressed. Further, since it is not necessary to attenuate unnecessary light, heat generation inside the projection device 400 can be suppressed. The control unit 430 also controls to output the input image data to the display element 460. The control unit 430 can also control the optical system. A part of the projection unit lens 475 is movable by a motor or the like, and is controlled by the control unit 430 to adjust zoom, focus, and the like.

The light source device 300 includes an excitation light source 310, a phosphor wheel 350, and an optical system. The optical system includes a dichroic mirror 322 and a mirror 325. The phosphor wheel 350 is a reflective type. The blue light, which is the light source, reflects the dichroic mirror 322 and is incident on the phosphor wheel 350, and the blue light that has passed is reflected by the three mirrors 325 and the dichroic mirror 322 and is incident on the display element 460. Further, the yellow light and the red light, which are the fluorescence emitted by the phosphor wheel 350, pass through the dichroic mirror 322 and enter the display element 460.

The light guide optical system 440 guides the irradiation light from the light source device 300 to the display element 460. The display element 460 processes the input image data for projection and outputs the data, and displays the image using the irradiation light guided by the light guide optical system 440. For the display element 460, for example, a DMD (Digital Micromirror Device) is used. The projection optical system 470 projects the image displayed by the display element 460 to the outside. The projection optical system 470 includes a projection lens 475. The projection optical system 470 may be composed of a plurality of lenses or mirrors. The configuration shown in this embodiment is an example, and each optical system may be composed of various lenses or mirrors depending on the application.

High illuminance is required for high-quality projection display that is not easily affected by external light. A combination light source of high-density excitation light and fluorescence has begun to be used in order to increase the amount of light of the light source and project it with high illuminance. By using the above-mentioned projection device 400, it is possible to maintain a high projection illuminance, and a good projection image can be obtained even in an environment with external light. In this way, the high-luminance projection device 400 can be configured. In the above embodiments, an example on the premise that the wavelength conversion plate is a reflective type is mainly described, but the present invention can be similarly applied even if the wavelength conversion plate is a transmissive type.

For the fluorescence of ruby phosphor particles, green excitation light that can obtain the optimum luminous efficiency in the visible light region is required. Therefore, it is important to stack YAG: Ce phosphor particles containing a green light emitting component on the side close to the excitation light source and emit light with a blue laser of the excitation light. Therefore, when constructing a transmission type wavelength conversion plate, it is preferable to arrange YAG: Ce phosphor particles on the transparent substrate side, arrange ruby phosphor particles on the upper layer, and irradiate excitation light from the transparent substrate side. preferable. In this case, it is not necessary to control the distribution by making the ruby phosphor particles larger than the YAG: Ce phosphor particles.

[Experiment]
(1. Synthesis of ruby phosphor particles)
In order to grasp the optimum Cr concentration of ruby (Al ₂ O ₃ : Cr ³⁺ ), first, ruby phosphor particles having different Cr concentrations were prepared and the luminous efficiency was evaluated. FIG. 7 is a table showing the material and composition of the ruby sample. The amount shown in FIG. 7 was weighed as a raw material and mixed with an agate mortar and pestle. BaF ₂ was added for the purpose of promoting the diffusion of Cr ³⁺ and increasing the crystallinity of alumina. At the start of mixing, a small amount of high-purity methanol was added so that the raw materials were sufficiently mixed in paste form.

The mixed powder of the raw material was lightly filled in an alumina crucible SSA-H (volume 15 mL) manufactured by Nikkato Co., Ltd., covered with an alumina lid, and fired at a high temperature of 1400 ° C. for 3 hours in the air. The electric furnace used was a box-shaped furnace UHB-2040G-II manufactured by Siliconit Co., Ltd. The calcined product taken out from the electric furnace is lightly crushed using an agate mortar and pestle, sieved with a nylon mesh (# 240), washed 3 times with hot water, and then 2 in air at 120 ° C. Drying for hours gave a ruby phosphor powder. An attempt was made to introduce Cr ³⁺ into Y ₃ Al ₅ O ₁₂ , which is the parent crystal of YAG: Ce, by the same method as in the production of ruby, but no luminescent material was obtained.

When these ruby phosphors were analyzed by powder X-ray diffraction, they all had the same crystal phase as α-Al ₂ O ₃ . Further, by observation using a scanning electron microscope (SEM), the produced phosphor particles had an average particle size of about 10 μm. Further, as a result of investigating the cation composition in the phosphor by high frequency inductively coupled plasma (ICP) emission spectroscopy, the amount of Cr added was almost the same as the charged composition.

(2. Optimal value of Cr concentration in ruby phosphor particles)
FIG. 8 is a graph showing the relationship between the Cr concentration of the ruby sample and the emission intensity. When the emission intensity of each sample of the above ruby sample was compared with the excitation light dispersed at 550 nm using a 150 W Xe lamp (excitation light output density of 0.1 W / cm ² or less) as a light source, the result shown in FIG. 8 was obtained. Obtained. It was found that the optimum value of Cr concentration was around 0.01, and the range of 0.005 to 0.013 was a practical concentration.

(3. Emission spectrum of phosphor particles)
Preparation composition (Al _0.990 Cr _0.010 ) ₂ O ₃ ruby samples were measured for excitation and emission spectra at room temperature using a fluorescence spectrophotometer FluoroMax-4 manufactured by Horiba Seisakusho Co., Ltd. (excitation). Light output density 0.001 to 0.01 W / cm ² ). FIG. 9 is a graph showing the spectrum of ruby excitation and emission. As shown in FIG. 9, ruby has a steep emission near 691 nm and an absorption band near 394 nm and 550 nm. Therefore, high-efficiency light emission with blue excitation near 450 nm cannot be expected so much. However, the green emission band of YAG: Ce and the absorption band on the long wavelength side of the ruby overlap each other, and it is possible to make the ruby emit red light through the emission of YAG: Ce by blue laser excitation. The excitation intensity of the laser is represented by the laser light output per irradiation spot area.

According to FIG. 9, two absorption bands having maximums near 394 nm and around 550 nm are observed, and sharp peak emission is observed near 691 nm. When a blue laser near 450 nm is used as the excitation light source, the excitation efficiency of ruby is not so high because it is close to the minimum of the excitation band.

Preparation composition (Al _0.990 Cr _0.010 ) A phosphor layer was prepared by mixing a ruby sample of ₂ O ₃ and commercially available YAG: Ce in a weight ratio of 1: 1 and a blue laser at room temperature of 455 nm. Was irradiated. FIG. 10 is a graph showing the emission spectrum of the phosphor layer sample and the spectral transmittance of the red filter. For comparison and control, a fluorescent layer containing only YAG: Ce was prepared in the same manner, and the measured emission spectrum is shown by a gray line. The spectral transmittance of the red filter used in the laser projector is also shown in FIG.

The decrease in emission corresponding to the long wavelength absorption band (maximum around about 550 nm) of the excitation spectrum shown in FIG. 9 was clearly observed in the mixed film of YAG: Ce and ruby, and instead a sharp peak was observed near 691 nm. The light emission that it has appears. Considering the spectral transmittance of the red filter shown by the broken line in FIG. 10, it can be seen that the integrated intensity of red emission is higher in the mixed phosphor layer with ruby than in the phosphor layer containing only YAG: Ce.

(4. Emission spectrum of mixed material)
The emission spectrum of the phosphor layer in which YAG: Ce phosphor particles and ruby phosphor particles were mixed at a weight ratio of 1: 1 was measured. The excitation light output density was 70 W / cm ² . As shown in FIG. 10, the emission spectrum intensity near 550 nm, which is the long wavelength side excitation band of ruby, is reduced as compared with the case of only YAG: Ce, but the ruby is excited by the light and sharpened near 690 nm. Luminescence was observed. Looking at the spectral transmittance of the red filter shown by the broken line in FIG. 10, it was found that even if the green component was cut, the overall intensity of the red component was increased by that amount. From this phenomenon, it was found that a red component can be produced by using, for example, a mixed film formed by mixing YAG: Ce phosphor particles and ruby phosphor particles in the phosphor layer of a laser projector.

(5. Mixing ratio and light emission characteristics)
With respect to the extraction light emitting part of the red component, a film was formed by changing the weight mixing ratio of the YAG: Ce phosphor particles and the ruby phosphor particles, excited by a blue laser, and the brightness was compared through a red filter. The excitation light output density was 70 W / cm ² . FIG. 11 is a graph showing the relationship between the mixing ratio of YAG: Ce phosphor particles and ruby phosphor particles and the amount of red light emitted. As a result of mixing the YAG: Ce phosphor particles and the ruby phosphor particles at a weight ratio of 2: 1 and forming a film, a light amount about 2% higher than that in the case of YAG: Ce alone was obtained.

In addition, the degree of redness was compared with CIE chromaticity coordinates. FIG. 12 is a graph showing the relationship between the mixing ratio of YAG: Ce and ruby and the red color tone. The higher the ratio of the yellow phosphor YAG: Ce, the smaller the chromaticity coordinate x and the larger the chromaticity coordinate y, and the redness tends to decrease. As a result of this evaluation, when considering both the intensity of the red component and the tint, the weight mixing ratio of the YAG: Ce phosphor particles and the ruby phosphor particles is preferably around 2: 1.

YAG: As the amount of ruby phosphor particles is increased with respect to Ce phosphor particles, the red color tone becomes deeper, but the brightness decreases. Referring to FIG. 11, the mixing amount m of the ruby phosphor particles with respect to the YAG: Ce phosphor particles, which exceeds the brightness realized by the combination of the YAG: Ce phosphor particles and the red filter alone, is 0 <m <0. It is 8. With this mixing amount, it is possible to improve the color tone of red.

If deep red light emission is required even if the brightness is sacrificed by about 5%, it is appropriate to limit the mixing amount m of the ruby phosphor particles to about 4.8. Therefore, in designing a red light source, it is valuable that the mixing amount m of the ruby phosphor particles with respect to the YAG: Ce phosphor particles is practically 0 <m ≦ 4.8. On the other hand, 0 <m <0.8 is appropriate, and 0.2 ≦ m ≦ 0.6 is more preferable as the mixing amount capable of achieving both brightness and color tone improvement.

(6. Average particle size and emission intensity)
YAG: The phosphor layers formed by changing the average particle diameters of the Ce phosphor particles and the ruby phosphor particles were irradiated with a blue laser and the brightness was compared through a red filter. The excitation light output density was 70 W / cm ² . FIG. 13 is a graph showing the relationship between the average particle size of the phosphor particles and the amount of red light emitted. The emission intensity of red is higher when the average particle size of the ruby phosphor is increased to about 20 μm. The red color tone was almost the same in the evaluation results.

(7. Layer structure and emission intensity)
Next, the relationship between the structure of the phosphor layer and the emission intensity was tested. First, ruby phosphor particles (average particle size of about 10 μm) were dispersed in an aqueous potassium silicate solution to form a phosphor layer having an average film thickness of about 35 μm by a sedimentation method. On the phosphor layer, YAG: Ce phosphor particles having an average particle size of about 10 μm were formed into a film having a thickness of about 70 μm by precipitation coating in the same manner as described above. For comparison, a mixture of YAG: Ce phosphor particles and ruby phosphor particles at a weight ratio of 2: 1 was similarly precipitated and coated to prepare a mixed phosphor layer having a film thickness of about 100 μm.

The large particle product of the ruby phosphor was prepared by increasing the amount of BaF ₂ added by about 20% as compared with the case of Example 1 and setting the synthesis temperature to 1450 ° C. The Cr concentration was adjusted to 0.01, and the result was expressed by chemical analysis (ICP method) as a composition formula (Al _0.990 Cr _0.010 ) ₂ O ₃ . By observing with a scanning electron microscope (SEM), it was confirmed that the powder had an average particle size of about 20 μm.

YAG: Ce and ruby phosphor weight ratio of 2: prepare a mixed powder of 1, potassium silicate _{(K 2 O · nSiO 2,} n is about 2.8) was dispersed in an aqueous solution, a phosphor layer by sedimentation coating did. In this phosphor layer, silica is responsible for the adhesion of the phosphor particles. The film thickness was approximately 100 μm. If a thicker film is required, a coating film using a liquid quantitative discharge device is suitable instead of the sedimentation coating method.

The brightness of the mixed phosphor layer of YAG: Ce and ruby phosphor and the phosphor layer coated with two layers was compared by irradiating a blue laser and passing through a red filter. The excitation light output density was 70 W / cm ² . FIG. 14 is a graph showing the relationship between the structure of the phosphor layer and the amount of red light emitted. In the phosphor layer coated with two layers, the emission intensity of red is higher than that when both phosphors are simply mixed. The red color tone was about the same.

(8. Presence / absence of ruby phosphor particles and emission intensity)
Next, a comparison was made between the case where the ruby phosphor particles were used in the red component extraction portion and the case where the ruby phosphor particles were not used. Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ (abbreviated as LuAG: Ce) was used as the green component, and YAG: Ce was used as the yellow component. Then, a film was formed on the red component extraction portion with a mixture of YAG: Ce phosphor particles and ruby phosphor particles at a weight ratio of 2: 1. As the phosphor layer, a mixture of the applied phosphor particles and the silicone resin was coated with a liquid quantitative discharge device. The film thickness of the central portion of the band on the arc was adjusted so as to be about 200 μm in each phosphor layer.

The white brightness obtained by using the phosphor wheel thus obtained was measured. The excitation light output density was 70 W / cm ² . Further, only YAG: Ce phosphor particles were used for the red component extraction portion, and the white brightness was measured under the same other conditions. FIG. 15 is a graph showing the relationship between the presence or absence of ruby in the phosphor layer and the white brightness. As shown in FIG. 15, the white brightness of the red component extraction section in which Ce phosphor particles and ruby phosphor particles are mixed at a weight ratio of 2: 1 is higher than that of the red component extraction section containing only YAG: Ce phosphor particles. Can be seen to have increased by 2%.

100, 300 Light source device 110, 310 Excitation light source 120, 140 Optical system lens 150, 250 Wavelength conversion plate 152, 252, 352 Substrate 155, 255, 355 Fluorescent layer 155a YAG: Ce Fluorescent particle 155b Ruby phosphor particle 160 Red Filter 256 YAG: Ce Fluorescent layer 257 Ruby phosphor layer 322 Dycroic mirror 325 Mirror 350 Fluorescent wheel 355a Red component extraction section 355b Yellow component extraction section 355c Green component extraction section 355d Blue component extraction section 360 Drive section 370 Fluorescent device 400 projection Device 410 Input unit 420 Sensor 430 Control unit 440 Light guide optical system 460 Display element (DMD)
470 Projection optics 475 Projection lens

Claims (9)

A light source device that extracts the red component
An excitation light source that irradiates a blue laser as excitation light,
YAG: A light source device including a phosphor layer containing Ce phosphor particles and ruby phosphor particles, and a wavelength conversion plate that receives the irradiated excitation light and emits wavelength band light. The light source device according to claim 1, wherein the ratio of the weight of the ruby phosphor particles contained in the phosphor layer to the weight of the YAG: Ce phosphor particles is 0.2 or more and 4.8 or less. The average particle size of the ruby phosphor particles is larger than the average particle size of the YAG: Ce phosphor particles.
The light source device according to claim 1 or 2, wherein the YAG: Ce phosphor particles are unevenly distributed on the side of the phosphor layer that receives the excitation light. In the phosphor layer, the layer containing the YAG: Ce phosphor particles and the layer containing the ruby phosphor particles are laminated.
The light source device according to claim 1 or 2, wherein a layer containing the YAG: Ce phosphor particles is arranged on the side of the phosphor layer that receives the excitation light. The light source device according to any one of claims 1 to 4, wherein the output density of the excitation light is 70 W / cm ² or more. The light source according to any one of claims 1 to 5, wherein the ruby phosphor particles have a composition of (Al _1-x Cr _x ) ₂ O ₃ and 0.005 ≦ x ≦ 0.015. apparatus. The wavelength conversion plate is a phosphor wheel that is configured to be capable of emitting multiple colors by providing the phosphor layer as a red component extraction portion in the circumferential direction and is rotatable with respect to the irradiation position of the excitation light. The light source device according to any one of claims 6. The light source device according to any one of claims 1 to 7.
A light guide optical system that guides the light emitted from the light source device, and
A display element that displays using the light guided by the light guide optical system based on the input image data, and
A projection optical system that projects the display to the outside,
A projection device including the light source device, the display element, and a control unit that controls each of the optical systems. The light source device according to claim 7 and
A light guide optical system that guides the light emitted from the light source device, and
A display element that displays using the light guided by the light guide optical system based on the input image data, and
A projection optical system that projects the display to the outside,
A control unit that controls the light source device, the display element, and each optical system,
A sensor that acquires the rotational position of the phosphor wheel and
It is provided with an output control unit that controls the output of the excitation light source.
The output control unit is a projection device that controls the output of the excitation light source according to the gradation of the color and brightness of the projected image to be output and the position information of the phosphor wheel acquired by the sensor.

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