JP2019039992A - Phosphor wheel, wheel device and projector - Google Patents

Abstract

To provide a phosphor wheel, a wheel device and a projector which have high light emission intensity for high-power use, hardly decrease in performance in spite of temperature extinction, and can reduce a risk of breakage due to excessive heat.SOLUTION: A phosphor wheel 10 comprises a substrate 12 which is formed in a disk shape and a phosphor layer 14 which is provided on the substrate 12, and converts light of wavelength within a specific range into light of different wavelength. The phosphor layer 14 is formed of a light-transmissive inorganic material 20 and phosphor particles 16 of 15 to 60 μm in average particle size, and 80 to less than 300 μm thick, and the phosphor particles 16 are formed of materials of YAG:Ce or LuAg: Ce, and have a Ce concentration of 0.60 at% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a phosphor wheel, a wheel device, and a projector.

  As a light emitting element, for example, a phosphor plate in which phosphor particles are dispersed in a resin typified by epoxy or silicone, which is disposed so as to be in contact with a blue LED element, is known. In recent years, applications using laser diodes (LDs), which have high energy efficiency and are easy to cope with downsizing and high output, are increasing in place of LEDs.

  Since the laser irradiates light with high energy locally, the irradiated portion of the resin irradiated with the laser beam intensively burns. On the other hand, by rotating the phosphor plate as a disk (wheel) shape, it is not limited to a single point of irradiation, but is made dynamic so that fluorescence in the case of using a high-energy excitation source such as a laser is used. The heat resistance of the body plate and the performance degradation caused by it were solved.

  Furthermore, Patent Document 1 discloses a technique for solving the problem of deterioration in the performance of the phosphor due to heat generation by providing the phosphor wheel with a heat sink. Further, Patent Document 2 has improved heat dissipation by dispersing phosphors with a glass matrix as a phosphor layer, pasting them through a metal wheel and a bonding layer, and bringing some of the phosphor particles into contact with the metal wheel. Technology is disclosed.

JP 2012-008177 A Japanese Patent Laying-Open No. 2015-094777

  Patent Document 1 discloses a technique using a resin, although the performance of the phosphor wheel is improved by increasing heat dissipation. With this technology, there is an unavoidable risk that the phosphor film will be burnt and damaged due to abnormalities such as stoppage of the rotating system and higher power, resulting in a temperature exceeding the heat resistance temperature of the resin. Further, the technique described in Patent Document 2 uses a resin only as a bonding layer, and the risk of damage from the film interface still remains. Accordingly, there is a demand for improving the heat resistance of the phosphor wheel itself as well as a means for improving heat dissipation.

  The present invention has been made in view of such circumstances, and has a high light emission intensity in high-power applications, is unlikely to deteriorate in performance due to temperature quenching, and can reduce the risk of damage due to excessive heat. An object is to provide a wheel, a wheel device, and a projector.

  (1) In order to achieve the above-mentioned object, the phosphor wheel of the present invention emits light having a wavelength in a specific range including a disk-shaped substrate and a phosphor layer provided on the substrate. A phosphor wheel for converting light of another wavelength, wherein the phosphor layer is formed of a translucent inorganic material and phosphor particles having an average particle diameter of 15 μm or more and 60 μm or less, and 80 μm or more and less than 300 μm The phosphor particles are made of either YAG: Ce or LuAG: Ce, and the Ce concentration of the phosphor particles is 0.60 at% or less.

  As a result, the phosphor layer can be thickened using a phosphor having a large particle size, and the emission intensity can be increased. Further, by reducing the concentration of Ce, which is an activator, temperature quenching can be suppressed even when a high-power laser diode is used as an excitation source, and the absorption rate of excitation light can be controlled within a small range. As a result, in combination with increasing the thickness of the phosphor layer using a phosphor with a large particle size, fluorescence conversion utilizing the deep part of the phosphor layer occurs, and the emission intensity is further improved. . Further, by constituting the phosphor layer only with an inorganic material, for example, it is possible to reduce the risk of breakage due to excessive heat due to, for example, stoppage of the wheel due to abnormalities in the rotating system or higher power.

  (2) Further, in the phosphor wheel of the present invention, the Ce concentration of the phosphor particles is 0.12 at% or more. Thus, since the Ce concentration is not too small, the absorption rate of the excitation light can be sufficiently maintained. As a result, the excitation light can be fully utilized, and the emission intensity is further improved.

  (3) In the phosphor wheel of the present invention, the phosphor layer has a thickness of 100 μm or more and 200 μm or less. This can reduce the risk of damage to the phosphor layer while maintaining high emission intensity.

  (4) Moreover, the phosphor wheel of the present invention is characterized in that the substrate is made of aluminum. Thus, by configuring the phosphor wheel using aluminum having high thermal conductivity, the heat generated in the phosphor layer can be efficiently radiated to the substrate. As a result, the risk of breakage due to excessive heat can be further reduced.

  (5) Moreover, the wheel device of this invention is a wheel device used for a projector, Comprising: The phosphor wheel in any one of said (1) to (4), The motor which rotates the said phosphor wheel, It is characterized by providing. As a result, a wheel device with high emission intensity and reduced risk of damage due to excessive heat can be configured, and the risk of damage can be reduced against abnormalities such as stopping of the rotating system.

  (6) Moreover, the projector of this invention is light-emitted from the light source which irradiates excitation light, the wheel device of the said (5) receiving the excitation light from the said light source, the display device which displays an image, and the said wheel device. And a projection optical system that projects an image displayed on the display device to the outside using the emitted light. As a result, a projector using a wheel device with high emission intensity and reduced damage risk due to excessive heat can be configured, and the damage risk can be reduced against abnormalities such as stoppage of the rotating system. Moreover, it can also be set as the silent design projector which used the light source device at low speed rotation.

  According to the present invention, it is possible to configure a phosphor wheel that has high emission intensity in high-power applications, is unlikely to deteriorate in performance due to temperature quenching, and can reduce the risk of damage due to excessive heat.

(A)-(c) is sectional drawing, the perspective view, and the top view which each represented the fluorescent substance wheel of this invention typically. It is the schematic diagram which expanded the cross section of the fluorescent substance layer part of a fluorescent substance wheel. It is a schematic diagram showing the wheel device of this invention. It is a conceptual diagram showing a part of projector of this invention. It is a flowchart which shows the manufacturing method of the phosphor wheel of this invention. It is sectional drawing which shows the reflection type evaluation system for the light emission intensity test with respect to a fluorescent substance wheel. It is a table | surface showing the result of various conditions of a sample, the light emission intensity at 24 W, and the presence or absence of peeling after 1 hour evaluation. It is a graph showing the emitted light intensity when taking a laser power density (laser input) on a horizontal axis about sample 11, A, and B. FIG. It is a table | surface which shows the result of the light emission intensity test at the time of the low rotation of a fluorescent substance wheel, and the presence or absence of the burning of the fluorescent substance layer after a measurement.

  Next, embodiments of the present invention will be described with reference to the drawings. In order to facilitate understanding of the description, the same reference numerals are given to the same components in the respective drawings, and duplicate descriptions are omitted. In the configuration diagram, the size of each component is conceptually represented and does not necessarily represent an actual dimensional ratio.

[Configuration of phosphor wheel]
1A to 1C are a cross-sectional view, a perspective view, and a plan view schematically showing the phosphor wheel 10, respectively. In the phosphor wheel 10, a phosphor layer 14 is formed on a substrate 12. The phosphor wheel 10 absorbs excitation light emitted from the light source, generates excitation light having different wavelengths, and emits radiation light. For example, the blue excitation light is absorbed and the conversion light different from the blue excitation light converted by the phosphor layer 14 is emitted, and the blue excitation light is reflected, and the converted light and the excitation light are combined, or Using only converted light, it can be converted into light of various colors.

  The substrate 12 is formed in a disc shape. As the material of the substrate 12, aluminum, iron, copper, or the like can be used. Although all of the substrate 12 can be manufactured from a material that reflects light, a material that reflects light, such as silver, may be provided by plating or the like on one surface of the material that does not consider light reflection. Moreover, since high temperature light is irradiated and temperature rises, it is better that heat conductivity is high. Therefore, the substrate 12 is preferably made of aluminum.

  FIG. 2 is an enlarged schematic view of the cross section of the phosphor layer 14 portion of the phosphor wheel 10. The phosphor layer 14 is provided as a film on the substrate 12 and is formed of phosphor particles 16 and a binding material 20 (translucent inorganic material). The binding material 20 fixes the phosphor particles 16 to each other and the phosphor particles 16 and the substrate 12. Thereby, since it has joined with the board | substrate 12 which functions as a heat sink with respect to irradiation of the light of a high energy density, it can thermally radiate efficiently and it can suppress the temperature quenching of a fluorescent substance. In addition, each of the above fixations is preferably a chemical bond in order to efficiently dissipate heat.

  The phosphor layer 14 is preferably formed in an annular shape having a certain width at a predetermined distance from the center of the substrate 12. By forming the phosphor layer 14 in an annular shape, the phosphor layer 14 is formed only at the excitation light irradiation portion and the vicinity thereof, and the weight of the phosphor wheel can be reduced and the cost can be reduced.

  The thickness of the phosphor layer 14 is not less than 80 μm and less than 300 μm. Moreover, it is preferable that they are 100 micrometers or more and 200 micrometers or less. This is because as the film thickness of the phosphor layer 14 increases, fluorescence conversion occurs in a relatively wide area within the film, and the light emission intensity is high. If the thickness of the phosphor layer 14 is too thick, problems due to heat storage increase, but this is solved by high heat dissipation by the rotating wheel structure and a decrease in the amount of heat generated by the use of a low Ce concentration phosphor (described later). Moreover, when the film thickness of the phosphor layer 14 is too thick, the risk of detachment of the phosphor particles 16 and peeling of the phosphor layer 14 increases, but there is no problem if it is less than 300 μm.

The phosphor particles 16 are configured by either yttrium aluminum garnet phosphor (YAG: Ce) or lutetium aluminum garnet phosphor (LuAG: Ce) to which cerium (Ce) is added as the emission center. Is done. At this time, the Ce concentration at the emission center is defined as follows. That is, the composition formula of YAG is Y ₃ Al ₅ O ₁₂ , but YAG in which a part of yttrium (Y) is replaced by Ce is represented as YAG: Ce, and the composition formula is generally represented by (Y _{3 —X} Ce _X ) Al ₅ O ₁₂ And the ratio of Ce with respect to the number of atoms of the whole composition formula is represented by unit "at%". For example, when X = 0.1, 0.1 / (3 + 5 + 12) × 100 = 0.5, which is defined as 0.5 at%.

LuAG is obtained by replacing all Y in YAG with lutetium (Lu), and the composition formula is Lu ₃ Al ₅ O ₁₂ . Therefore, the Ce concentration of LuAG: Ce is defined in the same manner as described above, and is expressed in the unit “at%”.

  The Ce concentration of the phosphor particles 16 is 0.60 at% or less. Thus, by using a phosphor with a low Ce concentration, the absorption rate of the excitation light of each phosphor particle 16 is reduced, and fluorescence conversion is performed using the deep part of the phosphor layer 14, and the entire light emission is performed. Strength is improved. In addition, by using a phosphor with a low Ce concentration, it is possible to disperse the heat generation points generated in the phosphor, reduce the density of heat generated during the fluorescence conversion, and increase the heat dissipation property, so that the temperature of the entire phosphor layer 14 is increased. The rise can be prevented. As a result, even when excited by a laser or the like having high energy, it becomes difficult to reach a temperature at which the light emission performance of the phosphor deteriorates, and a high light emission intensity can be maintained even at high power.

  Further, the Ce concentration of the phosphor particles 16 is preferably 0.12 at% or more. This is because if the Ce concentration is too small, the absorptivity of the excitation light is too low, and as a result, the emission intensity as a whole may be reduced.

  The Ce concentration of the phosphor particles can be analyzed by ICP or XRF. In either method, the phosphor having a known Ce concentration is used as a calibration curve. The Ce concentration may be obtained as an average value of a plurality of analysis values.

  The phosphor particles 16 absorb light source light (excitation light) and emit converted light. YAG: Ce absorbs light source light (excitation light) and emits yellow converted light. LuAG: Ce absorbs light source light (excitation light) and emits green converted light. For example, when the light source light is blue or purple, white light can be emitted by combining the light source light and the converted light.

  The average particle diameter of the phosphor particles 16 is 15 μm or more and 60 μm or less, and preferably 18 μm or more and 30 μm or less. This is because the emission intensity of the converted light is increased and the emission intensity of the phosphor wheel 10 is increased since the thickness is 15 μm or more. Moreover, since it is 60 micrometers or less, the degranulation of the fluorescent substance particle 16 at the time of rotating the fluorescent substance wheel 10 can be suppressed. Moreover, the temperature of each phosphor particle 16 can be kept low, and temperature quenching can be suppressed. In addition, in this specification, an average particle diameter is a median diameter (D50) or an average particle diameter in the particle | grains obtained by analysis of the SEM image. The average particle diameter which is the median diameter (D50) can be measured using dry measurement or wet measurement of a laser diffraction / scattering particle size distribution measuring apparatus. Moreover, the average particle diameter by analysis of a SEM image can be measured with the following method. For a cross section perpendicular to the planar direction of the phosphor layer 14, for example, an SEM image is acquired at 1000 times. Then, image analysis such as binarization is performed on the obtained SEM image, the cross-sectional area of 100 or more particles recognized as phosphor particles 16 is calculated from the image, and the average particle diameter is calculated from the cumulative distribution. Can be sought. When calculating the cross-sectional area of 100 or more particles recognized as phosphor particles from the image, a plurality of particles in the phosphor layer 14 are arranged so that the overall average particle diameter of the phosphor particles 16 included in the phosphor layer 14 is the same. Suppose that a cross-sectional image (for example, three or more) of a part is acquired.

The binding material 20 is formed by hydrolysis or oxidation of an inorganic binder, and is composed of an inorganic material having translucency. The binding material 20 is made of, for example, silica (SiO ₂ ) or aluminum phosphate. Since the binder 20 is made of an inorganic material, it does not change even when irradiated with high energy light such as a laser diode. Moreover, since the binder 20 has translucency, it can transmit excitation light and converted light. As the inorganic binder, ethyl silicate, an aluminum phosphate aqueous solution, or the like can be used.

  Note that a light-transmitting substance is a radiation of light emitted from the opposite side when light is vertically incident on a 0.5 mm target substance in a visible light wavelength region (λ = 380 to 780 nm). A substance whose bundle has characteristics that exceed 80% of incident light.

  The phosphor wheel 10 is composed of a phosphor having a large particle size, a thick phosphor layer, a phosphor having a low Ce concentration, and an inorganic material only. Therefore, it is suitable for high power applications. When used in high power applications, the emission intensity can be increased and the risk of breakage due to excessive heat can be reduced.

[Configuration of wheel device]
FIG. 3 is a schematic diagram showing the wheel device 50. The wheel device 50 includes the phosphor wheel 10 and a motor 60. The phosphor wheel 10 is the phosphor wheel 10 described above.

  The motor 60 rotates the phosphor wheel 10 to change the position where the excitation light of the phosphor layer 14 of the phosphor wheel 10 is irradiated. Thereby, since excitation light is not continuously irradiated to a part of the phosphor layer 14, heat generation of the phosphor layer 14 can be suppressed. Moreover, since air continues to hit the phosphor layer 14 and the substrate 12 functioning as a heat radiating plate while rotating, the heat generation of the phosphor layer 14 can also be suppressed by this.

[Projector configuration]
FIG. 4 is a conceptual diagram showing a part of the projector 100. The projector 100 includes a light source 110, a wheel device 50, a display device 120, and a projection optical system 130.

  The light source 110 emits excitation light that excites phosphors used in the wheel device 50. Since the phosphor used in the wheel device 50 is YAG: Ce or LuAG: Ce, the excitation light emitted by the light source 110 is preferably blue light or violet light. Further, since the phosphor wheel 10 used in the wheel device 50 is suitable for high power applications, the light source 110 is preferably a laser diode.

  The wheel device 50 is the wheel device 50 described above. The wheel device 50 receives the excitation light from the light source 110, absorbs the excitation light, excites it to generate converted light having different wavelengths, and emits the converted light alone or the emitted light composed of the converted light and the excitation light.

  The display device 120 displays an image projected by the projector 100. As the display device 120, a liquid crystal panel, a digital mirror device (DMD), or the like can be used.

  The projection optical system 130 projects the image displayed on the display device 120 to the outside using the emitted light emitted from the wheel device 50. The projection optical system 130 includes a plurality of lenses 131 and adjusts zoom and focus.

  In addition to the above-described configuration, the projector 100 includes a lens 131, a dichroic mirror 132, and the like. Further, depending on the design of the projector 100, a mirror, a dichroic mirror, a lens, a prism, or the like not shown in the figure can be used. Since the projector 100 is configured using the wheel device 50 with high emission intensity and reduced risk of damage due to excessive heat, the risk of damage can be reduced against abnormalities such as stoppage of the rotating system. Moreover, it can also be set as the silent design projector which used the wheel device 50 by low speed rotation.

[Method of manufacturing phosphor wheel]
An example of a method for manufacturing a phosphor wheel will be described. FIG. 5 is a flowchart showing a method for manufacturing a phosphor wheel according to the present invention. First, a substrate formed in a disk shape is prepared (step S1). Separately from this, a printing paste is prepared. First, phosphor particles having a predetermined Ce concentration and average particle diameter are prepared (step S2). The phosphor particles are either YAG: Ce or LuAG: Ce.

  Next, the prepared phosphor particles are weighed, dispersed in a solvent, and mixed with an inorganic binder to produce a printing paste (step S3). A ball mill or the like can be used for mixing. As the solvent, a high boiling point solvent such as α-terpineol, butanol, isophorone, glycerin or the like can be used.

  The inorganic binder is preferably an organic silicate such as ethyl silicate. By using the organic silicate, the phosphor particles are dispersed throughout the printing paste, and a printing paste having an appropriate viscosity can be produced. For example, when ethyl silicate is used as the inorganic binder, the amount of ethyl silicate is 70 wt% or more and 100 wt% or less, preferably 80 wt% or more and 90 wt% or less with respect to the mass of water and catalyst. In addition, the inorganic binder is obtained by reacting a raw material containing at least one member selected from the group consisting of a silicon oxide precursor that becomes silicon oxide by hydrolysis or oxidation, a silicate compound, silica, and amorphous silica at room temperature, or Or obtained by heat treatment at a temperature of 500 ° C. or lower. Examples of the silicon oxide precursor include those mainly composed of perhydropolysilazane, ethyl silicate, and methyl silicate.

  After producing the printing paste, the printing paste is applied on the substrate to form a paste layer (step S4). The printing paste can be applied by screen printing, spraying, drawing with a dispenser, or ink jet. The screen printing method is preferable because a thin paste layer can be stably formed. The paste layer is preferably formed in an annular shape. Further, the thickness of the paste layer is preferably adjusted to be 80 μm or more and less than 300 μm after firing.

  And the board | substrate with which the paste layer was formed is baked using an atmospheric furnace, and a fluorescent substance layer is produced (step S5). The firing temperature is preferably 150 ° C. or more and 500 ° C. or less, and the firing time is preferably 0.5 hours or more and 2.0 hours or less. Moreover, it is preferable that a temperature increase rate is 50 degreeC / h or more and 200 degrees C / h or less. Moreover, you may provide a drying process before baking.

  By such a manufacturing process, a phosphor wheel in which phosphor particles are uniformly dispersed in the entire phosphor layer can be easily manufactured. The obtained phosphor wheel can increase the emission intensity with high power and reduce the risk of breakage due to excessive heat.

[Example]
(Sample preparation method)
An aluminum substrate coated with silver on aluminum formed in a disk shape was prepared. Separately, phosphor particles (YAG: Ce particles) having an average particle diameter of 6 μm to 72 μm and a Ce concentration of 0.04 at% to 0.90 at% were prepared. These phosphor particles were weighed, α-terpineol (solvent) was mixed to prepare a dispersion, and ethyl silicate (inorganic binder) was mixed to prepare a printing paste.

  Next, a printing paste was applied to the substrate using a screen printing method so as to have a thickness of 20 to 300 μm after firing. After coating, the film was dried at 100 ° C. for 20 minutes, and then sealed with an inorganic binder. Finally, the temperature was raised to 350 ° C. at 150 ° C./h using an atmospheric furnace, and baked for 30 minutes to complete the sample.

  The Ce concentration of the sample was determined using ICP and using a phosphor having a known Ce concentration as a calibration curve. In addition, the film thickness (thickness) of the phosphor layer was obtained by taking a SEM cross-sectional photograph of each sample at a magnification of 1000 times and drawing 10 perpendicular lines at equal intervals from the top surface of the phosphor layer to the top surface of the substrate. And the film thickness of the phosphor layer was calculated from the average length of the 10 lines.

  (Sample evaluation method)

Each completed sample was fixed to a motor and rotated at a rotational speed of about 12000 rpm, and a light emission intensity test was performed by excitation with a laser having an input of 24 W at maximum. The wavelength of the excitation light was adjusted to 445 nm, and the irradiation diameter was adjusted to 0.15 mm ² with a condenser lens. FIG. 6 is a cross-sectional view showing a reflective evaluation system for a light emission intensity test on a phosphor wheel. As shown in FIG. 6, the evaluation system 700 includes a light source 710, a plano-convex lens 720, a biconvex lens 730, a band pass filter 735, and a power meter 740. Each element is arranged so that the emitted light from the phosphor wheel 10 can be collected and measured. Note that the sample S in FIG. 6 represents the phosphor layer portion of the rotating sample.

  The bandpass filter 735 is a filter that cuts light with a wavelength of 480 nm as a threshold, and a filter that cuts the larger wavelength side when measuring reflected excitation light (absorbed light) is used. Further, when measuring the emission intensity of the converted light, a filter that cuts the side with the smaller wavelength is used. Thus, in order to separate the transmitted excitation light from the converted light, it is installed between the biconvex lens and the power meter.

  In the system configured as described above, the excitation light that has entered the plano-convex lens 720 is collected at the focal point on the sample S of the phosphor wheel. Then, the radiated light generated from the sample S is collected by the biconvex lens 730, and the intensity of the light obtained by cutting the collected light by the band pass filter 735 is measured by the power meter 740. This measured value is taken as the emission intensity of the converted light. By condensing the laser beam with a lens and reducing the irradiation area, the energy density per unit area can be increased even with a low-power laser. This energy density is defined as the laser power density.

  FIG. 7 is a table showing various conditions of the sample, the light emission intensity at 24 W, and the result of the presence or absence of peeling after evaluation for 1 hour at 24 W. The emission intensity at 24 W was expressed as a relative value when the emission intensity of the phosphor wheel of Sample 1 was 100. This value is preferably 100 or more, but there is no problem if it does not greatly decrease. Moreover, what peeled slightly after evaluation for 1 hour at 24 W was judged to be unacceptable because it could not withstand long-term use.

  In the following description, when the average particle diameter of the phosphor particles is 6 μm or less, a small particle diameter, a medium particle diameter when it is larger than 6 μm and 14 μm or less, and a large particle diameter when it is larger than 14 μm are described. Further, when the Ce concentration of the phosphor particles is 0.60 at% or less, it is described as a low Ce concentration, and when it is higher than 0.60 at%, it is described as a high Ce concentration. Moreover, it describes as a thick film when the film thickness of a fluorescent substance layer is 80 micrometers or more, and a thin film when it is less than 80 micrometers.

  Samples 1 and 2 use resin for the phosphor layer, so there is a risk that the phosphor film may be burnt and damaged due to abnormalities such as stoppage of rotation system or higher power due to higher power. .

  Samples 3 to 6 are samples in which the thickness of the phosphor layer is changed using phosphor particles having a small particle size or medium particle size and a high Ce concentration. According to this, since the average particle size was small and the Ce concentration was high, the emission intensity was reduced regardless of the thickness of the phosphor layer. For this reason, it is understood that the larger the average particle size, the lower the Ce concentration.

  Compared with samples 7, 11, 12, 13, 9 and samples 14, 15, 16, 16, and 17 with the same average particle diameter and Ce concentration, the thickness of the phosphor layer is changed. However, the emission intensity increases. For this reason, it turns out that the one where the film thickness of a fluorescent substance layer is larger is preferable.

  Comparing sample 7 and sample 11, the emission intensity of sample 11 did not decrease, but the emission intensity of sample 7 slightly decreased because the phosphor layer was a thin film. For this reason, it turns out that it is preferable that the film thickness of a fluorescent substance layer is larger than 80 micrometers.

  When Sample 9 and Sample 13 were compared, Sample 13 did not peel even with a thick film, but Sample 9 caused slight peeling of the phosphor because the thickness of the phosphor layer was too large. For this reason, it turns out that the film thickness of a fluorescent substance layer should just be less than 300 micrometers.

  When Sample 8 and Sample 19 were compared, Sample 19 did not peel even when the particle size was large, but Sample 8 caused slight peeling of the phosphor because the average particle size was too large. For this reason, it turns out that an average particle diameter should just be 60 micrometers or less.

  Comparing sample 10 and sample 18, sample 18 improved the emission intensity at a low Ce concentration, but sample 10 had a lower Ce concentration, so the emission intensity slightly decreased. For this reason, it is understood that the Ce concentration is preferably 0.12 at% or more.

  FIG. 8 shows a phosphor prepared by using Sample B (medium particle size, 14 μm) and Sample A (small particle size, 6 μm) in which only the average particle size is changed based on Sample 11 (large particle size, 18 μm). It is a graph showing the emitted light intensity when taking a laser power density (laser input) on a horizontal axis about a wheel. As shown in FIG. 8, the phosphor particles used in the phosphor wheel have a larger emission intensity with respect to the same laser power density (laser input) when the average particle size is larger. For this reason, it is advantageous that the average particle size is large. In addition, since no temperature quenching has occurred in any of the samples until the input of 24 W, higher power can be achieved.

  FIG. 9 is a table showing the emission intensity test at the time of low rotation of the phosphor wheel and the result of the presence or absence of scorching of the phosphor layer after the measurement. With respect to Sample 1 and Sample 12, the emission intensity when the rotational speed was about 2000 rpm and the laser input was 10 W and the presence or absence of scorching of the phosphor layer after the measurement were measured. As a result, the emission intensity of Sample 1 was initially 53 for a laser input of 10 W, but decreased to 50 after 1 minute. Further, after the measurement, the presence or absence of scorching of the phosphor layer was examined, and it was confirmed that scorching occurred in a ring shape. This is because a resin is used for the phosphor layer. Burning did not occur even when the laser input was 24 W at high rotation, but burning occurred even at the laser input of 10 W at low rotation. In other words, it can be seen that when a resin is used for the phosphor layer, the temperature exceeds the heat resistance temperature of the resin due to an abnormality such as stoppage of the rotation system, and there is a risk that the phosphor film may burn and be damaged.

  On the other hand, the emission intensity of the sample 12 was 60 with respect to the laser input of 10 W, and it did not change even after 1 minute. Moreover, when the presence or absence of scorching of the phosphor layer was examined after the measurement, scorching did not occur. Thus, it has been found that the phosphor wheel of the present invention has a reduced risk of the phosphor film being damaged even when there is an abnormality such as a stop of the rotation system.

  From the above results, it was found that the phosphor wheel of the present invention has high emission intensity in high-power applications, is unlikely to deteriorate in performance due to temperature quenching, and can reduce the risk of breakage due to excessive heat.

DESCRIPTION OF SYMBOLS 10 Phosphor wheel 12 Substrate 14 Phosphor layer 16 Phosphor particle 20 Binder (inorganic material)
50 Wheel device 60 Motor 100 Projector 110 Light source 120 Display device 130 Projection optical system 700 Evaluation system 710 Light source 720 Plano-convex lens 730 Biconvex lens 735 Band pass filter 740 Power meter S Sample

Claims (6)

A substrate formed in a disk shape;
A phosphor wheel provided on the substrate, and a phosphor wheel for converting light of a specific range of wavelengths into light of other wavelengths,
The phosphor layer is formed of a translucent inorganic material and phosphor particles having an average particle diameter of 15 μm or more and 60 μm or less, and has a thickness of 80 μm or more and less than 300 μm,
The material of the phosphor particles is either YAG: Ce or LuAG: Ce,
The phosphor wheel according to claim 1, wherein a Ce concentration of the phosphor particles is 0.60 at% or less.   The phosphor wheel according to claim 1, wherein a Ce concentration of the phosphor particles is 0.12 at% or more.   The phosphor wheel according to claim 1, wherein the phosphor layer has a thickness of 100 μm or more and 200 μm or less.   The phosphor wheel according to any one of claims 1 to 3, wherein the substrate is made of aluminum. A wheel device used in a projector,
The phosphor wheel according to any one of claims 1 to 4,
A wheel device comprising: a motor that rotates the phosphor wheel. A light source that emits excitation light;
The wheel device according to claim 5, which receives excitation light from the light source;
A display device for displaying images;
A projection optical system that projects an image displayed on the display device to the outside using light emitted from the wheel device.

Images