阅读说明：本技术 色轮以及投影仪 (Color wheel and projector ) 是由 久保善则 藤本和良 于 2018-12-26 设计创作，主要内容包括：本公开的色轮具备：透明的基板(2),具备第1面(2a)、与该第1面(2a)对置的第2面(2b)、以及将第1面(2a)和第2面(2b)连接的外周面(2d)和内周面(2c),并具有旋转中心(1c)；着色部(3),被配置于基板(2)的第1面(2a),将从光源照射的激励光变换成波长不同的变换光；以及散热部(4),被配置于第1面(2a)或者第2面(2b)的至少任一个的激励光以及变换光的光路外的区域的、比着色部(3)更靠基板(2)的外周面(2d)或者内周面(2c)侧的位置,热传导率比基板(2)大。(The color wheel of the present disclosure includes: a transparent substrate (2) having a 1 st surface (2a), a 2 nd surface (2b) facing the 1 st surface (2a), and an outer peripheral surface (2d) and an inner peripheral surface (2c) connecting the 1 st surface (2a) and the 2 nd surface (2b), and having a rotation center (1 c); a coloring section (3) which is disposed on the 1 st surface (2a) of the substrate (2) and converts excitation light irradiated from a light source into converted light having a different wavelength; and a heat dissipation section (4) which is disposed in a region outside the optical path of the excitation light and the conversion light on at least one of the 1 st surface (2a) and the 2 nd surface (2b) and at a position closer to the outer peripheral surface (2d) or the inner peripheral surface (2c) of the substrate (2) than the coloring section (3), and has a thermal conductivity higher than that of the substrate (2).)

1. A color wheel includes:

a transparent substrate having a 1 st surface, a 2 nd surface opposed to the 1 st surface, and an outer peripheral surface and an inner peripheral surface connecting the 1 st surface and the 2 nd surface, and having a rotation center;

a colored portion disposed on the 1 st surface, for converting excitation light irradiated from a light source into converted light having different wavelengths; and

and a heat dissipation portion which is disposed in a region outside an optical path of the excitation light and the converted light on at least one of the 1 st surface and the 2 nd surface, and which is located closer to an outer peripheral surface or an inner peripheral surface of the substrate than the colored portion, and which has a thermal conductivity higher than that of the substrate.

2. The color wheel of claim 1 wherein,

the heat dissipation portion is disposed closer to the outer peripheral surface side than the colored portion.

3. The color wheel according to claim 1 or 2, wherein,

the heat dissipation part is provided at least on the 1 st surface.

4. The color wheel according to claim 1 or 2, wherein,

the heat dissipation part is provided on the 1 st surface and the 2 nd surface.

5. The color wheel of claim 4 wherein,

the heat dissipation portion is continuously disposed from the 1 st surface to the 2 nd surface.

6. A color wheel according to any of the claims 2 to 5 wherein,

the heat dissipating unit is provided on the 1 st surface on a side closer to a rotation center of the substrate than the colored portion.

7. The color wheel according to claim 1 or 2, wherein,

the heat dissipation part is provided on the 2 nd surface.

8. Color wheel according to any of claims 1 to 7,

the heat dissipation portion includes a metal portion and a glass portion.

9. Color wheel according to any of claims 1 to 8,

the substrate comprises sapphire.

10. Color wheel according to any of claims 1 to 9,

the heat dissipation portion has, in a cross-section perpendicular to the 1 st surface or the 2 nd surface: and a 1 st region including a surface in contact with the substrate and a 2 nd region including a surface on a side opposite to the substrate, wherein an area ratio of the glass portion in the 1 st region is larger than that in the 2 nd region.

11. The color wheel according to any of claims 8 to 10, wherein,

the area ratio of the glass portion in the cross section of the heat dissipation portion is 10% or less.

12. Color wheel according to any of claims 1 to 11,

the heat dissipation part has a plurality of air holes, and the ratio L/D of the average distance between centers of gravity L and the average circle-equivalent diameter D of the air holes is 4 or more.

13. The color wheel of claim 4 wherein,

the heat dissipation portion on the 1 st surface side and the heat dissipation portion on the 2 nd surface side overlap each other in a top perspective view from the 1 st surface side.

14. The color wheel of claim 1 wherein,

the heat dissipation part and the colored part on the same surface of the substrate are directly contacted.

15. The color wheel of claim 14 wherein,

the overlapping portion of the colored portion and the heat dissipating portion is laminated so that the heat dissipating portion is on the light source side.

16. A projector provided with a color wheel according to any of claims 1 to 15.

Technical Field

The present disclosure relates to a color wheel and a projector including the color wheel.

Background

Conventionally, a projector using a color wheel is known. A colored portion including a phosphor or the like is provided on one main surface of the color wheel, and converts light irradiated from a light source (light of the light source) into light of another wavelength (converted light). When the wavelength is converted, a part of the energy of the irradiated light becomes heat. Therefore, the surface of the color wheel on which the colored portion is provided is at a higher temperature than the opposite surface, and the color wheel is deformed (thermally deformed) by thermal expansion.

Fig. 8 of patent document 1 describes a color wheel having a wavelength conversion layer (colored portion) and a reflective layer on the front surface of a main body made of a transparent non-metallic material, and having a heat radiation fin made of metal or graphite on the rear surface thereof through a heat radiation adhesive layer at a position corresponding to the position of the wavelength conversion layer.

Fig. 7 and 8 of patent document 2 describe a color wheel including a 1 st glass layer provided on a 1 st main surface of a phosphor layer and a 2 nd glass layer provided on a 2 nd main surface of the phosphor layer, and a reflective layer including a metal provided on the 1 st glass layer, in which heat generated in the phosphor layer is emitted to the outside through the reflective layer.

The color wheel includes a transmissive type that emits the converted light on a surface opposite to a light irradiation surface of the light source, and a reflective type that emits the converted light on the same surface as the light irradiation surface of the light source. Patent documents 1 and 2 are structures for a reflection color wheel. For example, since the transmittance of visible light of a color wheel body made of sapphire is about 98%, and the reflectance of visible light of an aluminum reflective film used in a reflection-type color wheel is about 90%, the transmission-type color wheel has an advantage that the loss of light is less (power is saved) than the reflection-type color wheel. Since the light from the light source can be irradiated perpendicularly to the color wheel, the optical path is short, and a compact projector can be configured.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-111418

Patent document 2: japanese patent laid-open publication No. 2015-143824

Disclosure of Invention

The color wheel of the present disclosure includes: a transparent substrate having a 1 st surface, a 2 nd surface opposed to the 1 st surface, and an outer peripheral surface connecting the 1 st surface and the 2 nd surface, and having a rotation center; a colored portion disposed on the 1 st surface, for converting excitation light irradiated from a light source into converted light having different wavelengths; and a heat dissipation portion which is disposed in a region outside an optical path of the excitation light and the converted light on at least one of the 1 st surface and the 2 nd surface, and which is located closer to an outer peripheral surface or an inner peripheral surface of the substrate than the coloring portion, and which has a thermal conductivity higher than that of the substrate.

The projector of the present disclosure is provided with the color wheel.

Drawings

Fig. 1A is a schematic plan view showing an embodiment of the color wheel of the present disclosure.

FIG. 1B is a cross-sectional view taken along line A-A' of FIG. 1A.

Fig. 2A is a schematic top view showing another embodiment of the color wheel of the present disclosure.

Fig. 2B is a sectional view taken along line B-B' of fig. 2A.

Fig. 3A is a schematic top view showing another embodiment of the color wheel of the present disclosure.

Fig. 3B is a cross-sectional view taken along line C-C' of fig. 3A.

Fig. 4A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 4B is a cross-sectional view taken along line D-D' of fig. 4A.

Fig. 5A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 5B is a cross-sectional view taken along line E-E' of fig. 5A.

Fig. 6A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 6B is a sectional view taken along line F-F' of fig. 6A.

Fig. 7A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 7B is a sectional view taken along line G-G' of fig. 7A.

Fig. 8A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 8B is a sectional view taken along line H-H' of fig. 8A.

Fig. 9A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 9B is a sectional view taken along line I-I' of fig. 9A.

Fig. 10A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 10B is a sectional view taken along line J-J' of fig. 10A.

Fig. 11A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 11B is a cross-sectional view taken along line K-K' of fig. 11A.

Fig. 12A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 12B is a sectional view taken along line L-L' of fig. 12A.

Fig. 13A is a schematic plan view showing another embodiment of the color wheel of the present disclosure.

Fig. 13B is a cross-sectional view taken along line M-M' of fig. 13A.

Fig. 14A is a schematic plan view illustrating another embodiment of the color wheel of the present disclosure.

Fig. 14B is a cross-sectional view taken along line N-N' of fig. 14A.

Fig. 15 is a cross-sectional SEM photograph of an example of the color wheel of the present disclosure.

Fig. 16A is a schematic plan view showing a conventional color wheel.

Fig. 16B is a cross-sectional view taken along line X-X' of fig. 16A.

Detailed Description

< color wheel and projector >

The color wheel 1 and the projector of the present disclosure will be explained with reference to the drawings.

Fig. 1 is a schematic diagram showing an embodiment of a color wheel 1. Fig. 2 to 14 are schematic diagrams showing other embodiments of the color wheel 1. Fig. 15 is a sectional SEM photograph of the color wheel 1. Fig. 16 is a schematic diagram showing a conventional color wheel 20.

As shown in fig. 1, the color wheel 1 includes: a transparent substrate 2 having a 1 st surface 2a, a 2 nd surface 2b opposed to the 1 st surface 2a, and an inner peripheral surface 2c and an outer peripheral surface 2d connected to the 1 st surface 2a and the 2 nd surface 2 b; colored portions 3 (red colored portion 3R, green colored portion 3G) which are disposed on the 1 st surface 2a side of the substrate 2 and convert the excitation light into converted light having different wavelengths; and a heat dissipation portion 4 which is disposed at a position closer to the inner peripheral surface 2c than the colored portion 3 in a region outside the optical path of the excitation light and the converted light of at least one of the 1 st surface 2a and the 2 nd surface 2b, and has a thermal conductivity larger than that of the substrate 2. The color wheel 1 is used to rotate around a rotation center 1 c.

The projector (not shown) of the present disclosure includes: a light source for irradiating light to the color wheel 1, a rotation holding portion for holding and rotating the color wheel 1, and a digital mirror device having a plurality of micromirrors.

The color wheel 1 is thermally deformed by heat from the colored portion 3 that generates heat by irradiation light. Since the color wheel 1 is used while rotating at a high speed, the rotational speed changes when thermally deformed. When the thermal deformation of the color wheel 1 is large, damage may occur due to centrifugal force or contact with another member.

The heat of the heat dissipation portion 4 is dissipated to the surrounding air as the color wheel 1 rotates. The color wheel 1 has a larger area as the linear velocity during rotation increases toward the outer peripheral surface 2 d. The color wheel 1 includes the heat radiating portion 4 on the outer circumferential surface 2d side of the colored portion 3, and thus can increase the amount of heat radiation into the air.

The color wheel 1 has the above-described structure, and therefore, is excellent in heat resistance, heat dissipation, and rigidity, and is less likely to be thermally deformed. In particular, the color wheel 1 is suitable for a transmission type color wheel which emits converted light on a surface opposite to a light irradiation surface of a light source. The color wheel 1 can constitute a projector with high reliability. Further, the color wheel 1 can be combined with a high-output light source to constitute a high-luminance projector.

The thermal conductivity of the substrate 2 and the heat dissipation portion 4 can be measured by, for example, a laser flash method.

The substrate 2 has a disk shape, a diameter of 10mm to 200mm and a thickness of 0.1mm to 2.0 mm.

The substrate 2 comprises sapphire, for example. Sapphire is excellent as the substrate 2 in that it has excellent thermal conductivity and heat dissipation properties, can suppress temperature rise, has high rigidity and is difficult to deform, has relatively high mechanical strength and is difficult to break, and has high light transmittance. The substrate 2 may have a disc shape without the inner peripheral surface 2 c.

The colored portion 3 contains, for example, a phosphor. The color wheel 1 shown in fig. 1 includes a red colored portion 3R and a green colored portion 3G as the colored portions 3. As the light source used for such a color wheel 1, a blue laser or the like is used. The red color portion 3R and the green color portion 3G convert the irradiation light (blue) into red light and green light, and are formed in annular fan-shaped regions having a predetermined central angle (for example, 120 °).

The main component of the heat dissipation portion 4 is a metal having excellent thermal conductivity, such as silver, copper, gold, and aluminum. The thickness of the heat dissipation portion 4 is, for example, 10 μm to 1mm, preferably 50 μm to 200 μm. If the heat dissipation portion 4 is a metallized layer including a metal portion and a plurality of glass portions, the substrate 2 and the metal portion are firmly fastened by the glass portions existing in the vicinity of the interface between the heat dissipation portion 4 and the substrate 2. When the heat dissipation portion 4 includes a glass portion, the rigidity is higher than that of a simple metal. Therefore, the thermal deformation of the color wheel 1 can be reduced. The glass portion is, for example, glass containing silicon oxide as a main component. It is particularly preferable that the area ratio of the glass portion (hereinafter referred to as glass ratio) in a cross section perpendicular to the 1 st surface 2a or the 2 nd surface 2b of the heat dissipation portion 4 is 10% or less.

The heat dissipation portion 4 has: a 1 st region 4a including a surface contacting the substrate 2 in a cross-sectional view perpendicular to the 1 st surface 2a or the 2 nd surface 2 b; and a 2 nd region 4b including a surface on the opposite side of the substrate 2. When the glass ratio of the 1 st region 4a is larger than that of the 2 nd region 4b, the 1 st region 4a having a large glass ratio is fastened to the substrate 2 more strongly, and the 2 nd region 4b having a small glass ratio is used to increase the heat radiation performance of the entire heat radiation unit 4.

The heat dissipation portion 4 may further have a plurality of air holes. The air holes have a function of relaxing thermal stress and residual stress of the heat dissipation portion and suppressing deformation and breakage. However, if the pores are too large or the porosity is too large, the heat dissipation performance is lowered. Therefore, L/D, which is a ratio of the average inter-center-of-gravity distance L to the average circle-equivalent diameter D of the pores, is preferably 4 or more. If the L/D is 4 or more, both stress relaxation and heat dissipation performance can be achieved.

A cross-sectional SEM photograph (reflected electron image) of the color wheel 1 is shown in fig. 15. In the figure, the whitest part of the heat dissipation portion 4 is a metal portion, the black part is an air hole, and the middle brightness part of the metal portion and the black part is a glass portion. The air holes and the glass part are respectively provided in plurality. From such a cross-sectional SEM photograph, the glass ratio, the distance between the centers of gravity, and the circle equivalent diameter can be obtained using image analysis software. For example, the image analysis software "A image Jun" (Japanese "A image く'; registered trademark, manufactured by Asahi chemical Co., Ltd.) can be used as the setting conditions, and the lightness is defined as" lightness ", and the small pattern removal area is defined as" 0.1 μm²A noise removing filter is provided, and a threshold value which is an index indicating the brightness of an image is obtained by adjusting the shape of a mark appearing on a screen to be identical to the shape of a particle. In fig. 15, the glass ratio of the 1 st region 4a is 12.0%, the glass ratio of the 2 nd region is 4.9%,the glass ratio of the entire heat dissipation portion 4 was 8.0%. The average distance L between the centers of gravity of the pores was 7.7 μm, the average circle-equivalent diameter D of the pores was 1.4 μm, and L/D was 5.5.

In the color wheel 1, a 1 st surface 1a (corresponding to the 1 st surface 2a of the substrate 2) of the coloring portion 3 as a heat generation source is more likely to be at a higher temperature than a 2 nd surface 1b (corresponding to the 2 nd surface 2b of the substrate 2). When the color wheel 1 includes the heat dissipation portion 4 on the 1 st surface 2a side of the substrate 2, heat generated in the colored portion 3 can be quickly transmitted to the heat dissipation portion 4. Therefore, the distance between the colored portion 3 and the heat dissipating portion 4 is usually short, and it is particularly preferable if they are in direct contact with each other.

As shown in fig. 2 and 3, the color wheel 1 is preferably provided with a heat radiating portion 4 on the 2 nd surface 1b side because heat radiation from the 1 st surface 1b side is also increased. In particular, if the heat dissipation portion 4 is provided so as to face both the 1 st surface 1a side and the 1 st surface 1b side, the deformation of the color wheel 1 after the heat dissipation portion 4 is formed is small, which is preferable as described later.

As shown in fig. 4 and 5, when the color wheel 1 includes the heat radiating portion 4 closer to the rotation center 1c than the colored portion 3, the heat of the colored portion 3 can be radiated to the rotation holding portion by heat conduction, and therefore, the heat radiation performance is improved. As shown in fig. 6, it is particularly preferable to provide a heat dissipation portion 4 connecting the 1 st surface 2a side and the 2 nd surface 2b side of the substrate 2.

As shown in fig. 7, the color wheel 1 includes a heat radiating portion 41 having a thermal conductivity higher than that of the substrate 2 in the vicinity of the outer circumferential surface 2d of the 1 st surface 2a than the colored portion 3. The heat dissipation portion 41 may be located outside the optical path region of the excitation light. The heat dissipation portions 41 may be arranged at intervals, or may be an annular integrated body.

The color wheel 1 may further include a heat dissipation portion 41 on the 2 nd surface 2b side as shown in fig. 8 and 9. In this way, when the heat dissipation portion 41 is provided also on the 2 nd surface 2b side, the heat dissipation performance is also improved on the 2 nd surface 2b side. Therefore, the color wheel 1 further becomes difficult to be thermally deformed. In particular, when the heat dissipation portion 41 on the 1 st surface 2a and the heat dissipation portion 41 on the 2 nd surface 2b overlap each other in a plan view of the 1 st surface 2a, rotation failure and deformation due to a difference in position of the heat dissipation portion 41 are reduced.

Further, as shown in fig. 10 and 11, the natural color wheel 1 may further include a heat dissipation portion 42 closer to the rotation center 1c of the substrate 2 than the colored portion 3. When such a structure is satisfied, heat generated during wavelength conversion can be dissipated also at the center side of the substrate 2, and thus thermal deformation becomes difficult.

When the substrate 2 has the inner peripheral surface 2c, heat can be radiated to the rotation holding portion that holds the color wheel 1 by heat conduction, and therefore the heat radiation performance is improved. As a configuration for improving the heat dissipation performance, as shown in fig. 9, a heat dissipation portion 41 may be provided from the 1 st surface 2a to the 2 nd surface 2b of the substrate 2. The heat dissipation portion 41 and the heat dissipation portion 42 are the same as the heat dissipation portion 4 described above.

The color wheel 1 shown in fig. 12 includes a heat dissipation portion 4 having a thermal conductivity higher than that of the substrate 2, outside the optical path region on the 2 nd surface 2 b.

Since the color wheel 1 shown in fig. 12 includes the heat dissipation portion 4 having a thermal conductivity higher than that of the substrate 2 outside the optical path region on the 2 nd surface 2b, heat transfer from the 1 st surface 2a to the 2 nd surface 2b in the thickness direction of the substrate 2 is promoted, and thermal deformation is reduced by heat dissipation by the heat dissipation portion 4.

The heat generated at the time of wavelength conversion is radiated to the peripheral air as the color wheel 1 rotates. The color wheel 1 has a larger area as the linear velocity during rotation increases toward the outer peripheral surface 2 d. When the color wheel 1 includes the heat radiating portion 4 on the outer peripheral surface 2d side in the light path outer region as shown in fig. 12 and 14, the amount of heat radiated into the air can be increased. Therefore, the heat radiation performance is improved, and the color wheel 1 becomes difficult to thermally deform.

As shown in fig. 13 and 14, the color wheel 1 may further include a heat dissipation portion 4 in the vicinity of the center 1c of the substrate 2 in the light path outer region. When such a structure is satisfied, the thermal deformation at the center side of the substrate 2 becomes small. In the color wheel 1, the 1 st surface 2a having the colored portion 3 is heated to a higher temperature than the 2 nd surface 2b at the time of wavelength conversion, and the 1 st surface 2a is thermally deformed to be convex, however, the heat is dissipated to the 2 nd surface 2b side by providing the heat dissipating portion 4 in the vicinity of the center of the substrate 2 in the region outside the optical path. Therefore, the thermal deformation of the 1 st surface 2a which becomes convex is suppressed.

When the 1 st surface 2a of the color wheel 1 becomes higher in temperature than the 2 nd surface 2b during the wavelength deformation, the substrate 2 is thermally deformed in a direction in which the 1 st surface 2a becomes convex. The substrate 2 may be concave when the wavelength conversion is not performed on the 1 st surface 2a including the colored portion 3. When the residual stress of the color wheel 1 has a stress that cancels out the thermal stress due to heat generation of the colored portion 3, or is in a range larger than the thermal stress due to heat generation of the colored portion 3, the deformation is suppressed, which is preferable.

Specifically, when the heat dissipation portion 4 is formed by a method such as firing that is higher than room temperature, residual stress is generated in the substrate 2 and the heat dissipation portion 4 due to a difference between the formation temperature and the room temperature and a difference between the thermal expansion coefficients of the substrate 2 and the heat dissipation portion 4. In general, since metal has a large thermal expansion coefficient, a deformation occurs in which the surface of the substrate 2 on which the heat dissipation portion 4 is formed has a compressive stress and the surface on which the heat dissipation portion 4 is formed has a concave shape.

When the color wheel 1 includes the heat dissipation portion 4 formed at a high temperature on the 1 st surface 2a side, the 1 st surface 2a is concave, and thermal deformation of the 1 st surface 2a to a convex shape during wavelength conversion is suppressed. This is presumed to be because the residual stress on the 1 st surface 2a and the thermal stress during wavelength conversion are balanced.

When the color wheel 1 includes the heat dissipation portion 4 on both the 1 st surface 1a and the 2 nd surface 1b, residual stress caused by the formation of the heat dissipation portion 4 is balanced out, and deformation of the color wheel 1 after the formation of the heat dissipation portion 4 is reduced, which is preferable. In particular, in the arrangement in which the heat dissipation portions 4 located on the 1 st surface 2a and the 2 nd surface 2b overlap each other in a plan view of the 1 st surface 2a, deformation of the substrate 2 at the time of forming the heat dissipation portions 4 can be suppressed. The heat dissipation portions 4 of the 1 st surface 1a and the 2 nd surface 1b are appropriately designed (position, area, thickness, and the like) in accordance with the use conditions (heating conditions) of the color wheel 1, whereby the deformation of the color wheel 1 can be further suppressed.

The light source of the projector may be disposed on the 1 st surface 1a side or the 2 nd surface 1b side of the color wheel 1. When the converted light from the color wheel 1 of the coloring portion 3 is emitted on the 1 st surface 1a side (in the case of a transmissive projector, the light source is disposed on the 2 nd surface 1b side), attenuation of the amount of light due to the transmission of the converted light through the substrate 2 does not occur, which is particularly preferable. When the colored portion 3 and the heat dissipation portion 4 are in direct contact, it is preferable that the heat of the colored portion 3 is quickly transferred to the heat dissipation portion 4 when the overlapping portion of the colored portion 3 and the heat dissipation portion 4 is laminated so that the heat dissipation portion 4 is on the light source side.

< method for manufacturing color wheel >

A method for manufacturing the color wheel 1 of the present embodiment will be described.

First, a sapphire plate as a material of the substrate 2 is prepared. A sapphire ingot grown from polycrystalline alumina as a raw material is cut and processed to form a sapphire plate. The sapphire plate is, for example, a disk having a diameter of 10mm to 200mm and a thickness of 0.1mm to 2.0 mm.

The method of growing the sapphire ingot is not particularly limited. Sapphire ingots grown by the EFG (Edge-defined film-fed Growth) method, CZ (czochralski method), Kyropoulos (Kyropoulos) method, or the like can be used.

Then, a fixing hole or the like for fixing the substrate 2 to the spin holder is formed in the sapphire plate.

Next, the sapphire plate was processed by a grinding apparatus so that the arithmetic average roughness Ra of both principal surfaces of the sapphire plate became 1.0 μm or less. Grinding can be performed, for example, by using a platen made of cast iron and diamond grit having an average particle size of 25 μm in a dead weight mode.

The arithmetic average roughness Ra in the present specification is a value based on JIS B0601 (2013). The arithmetic mean roughness Ra can be measured, for example, using a laser microscope device VK-9510 manufactured by KEYENCE. The measurement conditions may be, for example, that the measurement mode is a color super depth, the measurement magnification is 1000 times, the measurement pitch is 0.02 μm, the cutoff filter λ s is 2.5 μm, the cutoff filter λ c is 0.08mm, and the measurement length is 100 μm to 500 μm.

After the grinding, a heat treatment for reducing residual stress and crystal defects on the surface and inside of the sapphire plate or improving the transmittance of light may be performed. As specific conditions for the heat treatment, the sapphire plate is held at a temperature of 1800 ℃ to 2000 ℃ for 5 hours or more in an inert gas atmosphere such as argon or in vacuum, and then cooled to room temperature over a cooling time of 6 hours or more. Accordingly, atoms are rearranged on the surface and inside of the sapphire substrate, crystal defects and internal stress are reduced, and light transmittance is improved.

Next, CMP (Chemical Mechanical Polishing) using colloidal silica is performed, and both principal surfaces of the sapphire plate are mirror polished so that the arithmetic average roughness Ra is 30nm or less, preferably 1nm or less, thereby manufacturing the substrate 2.

Then, a phosphor or a color filter to be the colored portion 3 is formed in a desired region of the 1 st surface 2a of the substrate 2 by a method such as vapor deposition, coating, and baking.

Further, a heat dissipation portion 4 containing silver, copper, gold, aluminum, or the like is formed by a method such as vapor deposition, coating, or baking in a region outside the optical path of the excitation light and the converted light (including at least a region closer to the outer circumferential surface 2d than the colored portion 3) in a desired region of at least one of the 1 st surface 2a or the 2 nd surface 2b of the substrate 2. The heat dissipation portion 4 may be formed by coating and firing a composition containing metal powder and glass powder.

When the heat dissipation portion 4 is formed at a high temperature, residual stress occurs in the substrate 2 and the heat dissipation portion 4. When the forming temperature of the heat dissipating portion 4 is 600 ℃ or higher, the residual stress is relatively large compared to the thermal stress due to heat generation of the colored portion 3, and the deformation of the color wheel 1 is suppressed, which is preferable.

As described above, the method for manufacturing the color wheel 1 according to the present disclosure includes the steps of: preparing a transparent substrate 2 having a 1 st surface 2a, a 2 nd surface 2b opposed to the 1 st surface 2a, and an inner peripheral surface 2c and an outer peripheral surface 2d connecting the 1 st surface 2a and the 2 nd surface 2 b; forming a colored portion 3 on the 1 st surface 2a, the colored portion converting excitation light emitted from a light source into converted light having a different wavelength; and a step of forming a heat dissipation portion 4 having a thermal conductivity higher than that of the substrate 2 in a region on the outer peripheral surface 2d side of the colored portion 3 out of the optical path of the excitation light and the converted light of at least one of the 1 st surface 2a and the 2 nd surface 2 b. Therefore, a color wheel which is difficult to thermally deform can be provided.

Either one of the colored portion 3 and the heat dissipating portion 4 may be formed first. If the colored portion 3 is formed prior to or simultaneously with the heat dissipation portion 4, the residual stress generated by the formation of the heat dissipation portion 4 does not change, which is preferable. When the heat dissipation portion 4 is formed prior to the colored portion 3, damage to the colored portion 3 due to heat generated when the heat dissipation portion 4 is fired does not exist, and the degree of freedom of the firing conditions of the heat dissipation portion 4 is preferably improved.

Such a color wheel can also be applied to a transmission type color wheel in which the converted light is transmitted to the side opposite to the light source. Therefore, it is possible to provide a color wheel which is less likely to be thermally deformed, and a projector having the color wheel and high reliability.

While the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various improvements and modifications may be made within the scope of the claims. For example, the color wheel 1 may be provided with an antireflection film for reducing reflection of light from the light source on a surface on which light from the light source enters, or may be provided with a color separation film for reflecting light converted and transmitting the light from the light source on a side opposite to the side of the color section 3 on which light is converted.