Phosphor wheel device, illuminator, and projection type image display device

Abstract

This phosphor wheel device includes: a disk-shaped base material made of a heat conductive material; a phosphor ring disposed on a front surface constituting one surface of the base material as an annular shape concentric with a disk center or a part of the annular shape; and a motor for rotating the base material around a rotation center axis passing through the disk center. A plurality of first blade parts and a plurality of second blade parts are provided on a rear surface constituting the other surface of the base material so as to be rotationally symmetrical about the disk center. The second blade part has a lower blade height in the rotation center axis direction and a smaller thickness in the rotation direction of the base material than the first blade part.

Description

Phosphor Wheel Device, Lighting Device, and Projection-Type Image Display Device

[0001] The present disclosure relates to a phosphor wheel device, a lighting device, and a projection-type image display device.

[0002] Patent Document 1 discloses a light source device including a light source, an optical element into which light emitted from the light source is incident, and a rotating device that rotates the optical element. The optical element includes a substrate rotated by the rotating device, an optical element layer located on a first surface on which the light emitted from the light source is incident on the substrate and disposed inside the outer edge of the substrate along the rotation direction of the substrate, and a heat radiating portion located on at least one of the first surface and a second surface opposite to the first surface. The heat radiating portion extends from the rotation center side to the outer peripheral side of the optical element and has a plurality of fins arranged along the rotation direction. The dimension along the rotation direction between two adjacent fins among the plurality of fins is set within a predetermined dimension range.

[0003] Japanese Patent Application Laid-Open No. 2017-215536

[0004] The present disclosure provides a phosphor wheel device, a lighting device, and a projection-type image display device that efficiently cools heat generation in a phosphor with a simple configuration.

[0005] The present disclosure provides a phosphor wheel device including a disk-shaped base material made of a heat conductive material, a phosphor ring arranged as an annular shape or a part of an annular shape concentric with the disk center on a surface which is one surface of the base material, and a motor that rotates the base material around a rotation center axis passing through the disk center. On a back surface which is the other surface of the base material, a plurality of first blade portions and a plurality of second blade portions are provided rotationally symmetrically about the disk center. The second blade portion has a lower blade height in the rotation center axis direction and a thinner thickness in the rotation direction of the base material compared to the first blade portion.

[0006] According to the present disclosure, heat generation in the phosphor can be efficiently cooled with a simple configuration.

[0007] Schematic diagram of a projection-type image display device according to Embodiment 1 Diagram showing the configuration of the lighting device according to Embodiment 1 Front view showing the surface side of the phosphor wheel device Cross-sectional view of a substrate on which a phosphor ring is provided, cut at position A-A in Figure 3 Rear view of the substrate as seen from the back Side view of the substrate shown in Figure 5 Cross-sectional view of the substrate with the phosphor ring arranged on the substrate Rear view of the substrate showing the positional relationship between the phosphor ring, indicated by the dashed line in Figure 5, and the first and second blades Enlarged view of a key part of Figure 5 Enlarged perspective view of a key part of Figure 5 Correlation diagram showing the rate of change relative to 100% when only the first blade is present on the vertical axis, and the ratio of the height of the second blade to the height of the first blade on the horizontal axis Correlation diagram showing the relationship between the thickness of the second blade and inertia Correlation diagram showing the deflection when a load is applied to the blade end of the second blade Correlation diagram showing fin efficiency on the vertical axis and the ratio of the height of the second blade to the height of the first blade on the horizontal axis

[0008] (Background to this disclosure) Due to advances in solid-state light source technology, projection-type image display devices are seeing a shift in their light sources from conventional discharge lamps to LEDs and lasers, which have advantages such as long lifespan, mercury-free properties, and non-explosive capabilities. In particular, while the light output from a single laser is small, its relatively low etendue allows for the use of multiple lasers in array-like units as light sources, and high-output projectors exceeding 5000 lumens have been commercialized. Furthermore, lasers that emit blue wavelength light are superior in both efficiency and output, and the mainstream configuration involves combining these with phosphors that produce yellow light upon receiving blue light to obtain white light.

[0009] Even projection-type image display devices equipped with these solid-state light sources are required to have high output power. On the other hand, even with relatively efficient YAG-based light sources, only about half of the incident energy can be used as light, with the remainder being converted into heat. If this heat is not removed, it will lead to a decrease in fluorescence efficiency and reliability due to an increase in the phosphor temperature. Therefore, generally, the phosphor is formed into a ring shape and rotated by a motor to increase the effective surface area of ​​the phosphor and promote heat exchange with the air, even when the excitation light from the laser is focused as a point. In recent years, even in such configurations where the phosphor is formed into a ring shape and rotated by a motor, there has been a demand for even higher brightness, and it is necessary to realize phosphors and their configurations that efficiently convert incident light, as well as cooling means that can achieve this at low cost.

[0010] Therefore, the following embodiments describe examples of a phosphor wheel device, a lighting device, and a projection-type image display device that can efficiently cool the heat generated in a phosphor with a simple configuration.

[0011] Hereinafter, embodiments of the phosphor wheel apparatus, illumination apparatus, and projection image display apparatus disclosed herein will be described in detail with reference to the drawings as appropriate. However, unnecessarily detailed explanations may be omitted. For example, detailed explanations of already well-known matters and redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. The accompanying drawings and the following explanation are provided to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0012] Figure 1 is a schematic diagram of a projection-type image display device 200 according to Embodiment 1 of the present disclosure. The projection-type image display device 200 according to Embodiment 1 has an illumination device 201, a relay optical system 208 that guides light from the illumination device 201, a total internal reflection prism 213, a color prism unit 218, and a projection lens 225.

[0013] The lighting device 201 is constructed by adding a blue light path system 300 and a dichroic mirror 207 to the lighting device 100 (see Figure 2). The blue light path system 300 emits blue light in the +X direction from a light source 202 equipped with multiple blue laser diodes and corresponding collimating lenses. The emitted blue light is focused and parallelized by lenses 203 and 204 that constitute the afocal system, but when it is incident on a diffuser plate 205 provided near the convergence point, the intensity distribution is converted to be relatively smooth. The converted blue light is reflected by mirror 206 and incident on a dichroic mirror 207 which has the characteristic of transmitting light of colors other than blue light.

[0014] The dichroic mirror 207 superimposes the yellow light that has passed through the dichroic mirror 105 of the illumination device 100 and the blue light incident from the mirror 206 onto the same optical axis. In this way, the light incident on the lens 113 becomes yellow light and blue light, which then enter the relay optical system 208 via the lens 114 and the rod integrator 115.

[0015] Light emitted from the rod integrator 115 passes through relay lenses 209 and 210, is reflected by the folding mirror 211, then passes through the field lens 212, and enters the total internal reflection prism 213. The total internal reflection prism 213 is made up of a first prism 214 and a second prism 215 fixed together with a small gap (air gap) between them. Light incident on the total internal reflection prism 213 is totally reflected by surface 216, then passes through surface 217 and enters the color prism unit 218.

[0016] This color prism unit 218 is formed by bonding together a first prism 220 having a blue-transmitting dichroic mirror surface 219 that reflects blue light, and a second prism 222 and a third prism 223 having a green-transmitting dichroic mirror surface 221 that reflects red and blue light. However, an air gap is provided between the first prism 220 and the second prism 222 to utilize total internal reflection.

[0017] Each prism end face is equipped with DMD224R, 224G, and 224B as shown in the figure. These DMDs (Digital Micromirror Devices) consist of tiny mirrors arranged in two dimensions, and their tilt direction is controlled in two directions according to the external video signal. When the signal is ON, the reflected light returns to the color prism unit 218 at an incident angle of 0°, and when the signal is OFF, it is incident on the color prism unit 218 again at a larger angle. DMD224B is for blue light modulation, DMD224R is for red light modulation, and DMD224G is for green light modulation.

[0018] In the DMD224R, 224G, and 224B, the pixels in white display mode return to the color prism unit 218, and after passing through there, they pass through the first prism 214 and second prism 215 of the total internal reflection prism 213, enter the projection lens 225, and reach a screen (not shown). Therefore, the projection-type image display device 200 can achieve color projection display on the screen by inputting different signals to the DMD224R, 224G, and 224B.

[0019] Next, the lighting device 100 will be described.

[0020] Figure 2 shows the configuration of the lighting device 100 according to Embodiment 1. Blue light emitted in the Y direction from a light source 101, which is equipped with a plurality of blue laser diodes for excitation light sources and collimating lenses paired with them, is focused and parallelized by lenses 102 and 103 that constitute the afocal system and incident on a diffuser plate 104. The blue laser light incident on the diffuser plate 104 is diffused there and then incident on a dichroic mirror 105 which has the characteristic of reflecting blue light and transmitting other colored light.

[0021] The dichroic mirror 105 is positioned at a 45-degree angle to the optical axis, and the blue light from the diffuser plate 104 is reflected here, passes through the condenser lens 106, and is focused onto the phosphor ring 109 formed in an annular shape on the substrate 108 of the phosphor wheel device 107. Since the substrate 108 of the phosphor wheel device is rotated by the motor 110, even when the energy of the irradiated light is high, the incident area on the periphery of the phosphor involved in fluorescence is increased, and heat generation during fluorescence can be suppressed (see Figure 3).

[0022] Here, the phosphor ring 109 has the characteristic of emitting yellow light when it receives blue light as excitation light. As shown in Figure 4, the yellow fluorescence is reflected by the filler 112 contained in the adhesive layer 111 applied between the phosphor ring 109 and the substrate 108 and returned in the +X direction. The returned yellow fluorescence passes through the condenser lens 106 and is then incident on the dichroic mirror 105 again. Here, the dichroic mirror 105 has the characteristic of transmitting light of colors other than blue light. Therefore, the yellow fluorescence incident on the dichroic mirror 105 passes through it and proceeds in the +X direction. The yellow light incident on lenses 113 and 114 is focused on the incident surface of the rod integrator 115, which has a rectangular aperture and is positioned in front of it.

[0023] In this way, the illumination device 100 can generate yellow light from blue excitation light. In this configuration, the final output is the light emitted from the rod integrator 115, and the necessary optical system (the relay optical system 208, total internal reflection prism 213, color prism unit 218, etc.) is provided in front of the emission surface to perform its function. Note that the rod integrator 115 is not an essential component of the illumination device 100; a lens array consisting of rectangular lenses can be used instead of lenses 113, 114 and the rod integrator 115.

[0024] The projection-type image display device 200 shown in Figure 1 has an illumination device 201. The illumination device 201 is constructed by adding a blue light path system 300 and a dichroic mirror 207 to the illumination device 100 (see Figure 2). The illumination device 201 superimposes the blue light emitted from the blue light path system 300 and the yellow fluorescence emitted from the phosphor ring 109 provided on the illumination device 100 onto the same optical axis using the dichroic mirror 207, and then causes them to enter the lens 113. As a result, the projection-type image display device 200 causes the blue light and yellow light emitted from the lens 113 to enter the relay optical system 208.

[0025] Next, the configuration of the phosphor wheel device 107 will be described in detail below.

[0026] Figure 3 is a front view showing the surface side of the phosphor wheel device. The phosphor ring 109 is formed on the phosphor ring mounting surface 301, which is one surface of the base material 108, at a predetermined distance from the center of the base material 108 (disk center O), such that the center of the base material 108 and the center of the phosphor ring 109 are coaxial. This phosphor ring 109 is made of ceramic formed by firing phosphor. The phosphor used is one that emits yellow light (yellow fluorescence) when exposed to blue light.

[0027] A shaft hole 303 is formed in the center of the base material 108 into which the rotating shaft 302 of the motor 110 is inserted. On the radially outer side of the shaft hole 303, a plurality of rotation restricting holes 304 are formed at equal intervals in the circumferential direction. Rotation restricting pins 305, which rotate integrally with the rotating shaft 302, are inserted into the rotation restricting holes 304.

[0028] Figure 4 is a cross-sectional view of the substrate 108 on which the phosphor ring 109 is provided, cut at position A-A in Figure 3. The phosphor ring 109 is fixed to the substrate 108 by an adhesive layer 111. Filler 112 is kneaded into this adhesive layer 111 so as to be diffusely distributed. In other words, the layer containing filler 112 is the adhesive layer 111 containing filler 112. Filler 112 has a higher thermal conductivity than the material of the adhesive layer 111 and has higher light reflectivity than the substrate 108. That is, a layer containing filler 112, which has a higher reflectivity and superior thermal conductivity than the substrate 108, is provided between the phosphor ring 109 and the substrate 108. For example, titanium oxide can be used as the material for filler 112.

[0029] On the other hand, the base material 108 is assumed to be an aluminum alloy due to its thermal conductivity, availability, and processability. The phosphor in the phosphor ring 109, upon receiving excitation light, emits light without directionality. However, the light emitted in the direction of the base material 108 is reflected by the filler 112 (titanium oxide) in the adhesive layer 111 before reaching the base material 108, re-enters the phosphor ring 109, passes through the adhesive layer 111, and is emitted from the surface side of the phosphor ring 109.

[0030] As a result, the reflective layer that was conventionally provided on the surface of the substrate 108 is no longer necessary. If the reflective layer was formed by vapor deposition or the like, it would be very expensive, but with the configuration according to the present invention, the same performance can be achieved at a low cost by eliminating this layer.

[0031] In this example, titanium oxide was used for filler 112, but other materials with superior thermal conductivity and reflectivity can be used; for example, zinc oxide can achieve a similar effect. Furthermore, while ceramic phosphor was used for the phosphor ring 109, a similar effect can be obtained by further coating the titanium oxide-coated substrate 108 with an organic phosphor, which is a mixture of phosphor powder and a resin binder.

[0032] On the back surface 118 of the substrate 108, opposite to the phosphor ring mounting surface 301 which is the surface of the substrate 108 on which the phosphor ring 109 is attached, a first wing-shaped protrusion (hereinafter referred to as the first wing portion 116) and a second wing-shaped protrusion (hereinafter referred to as the second wing portion 117) are provided. The first wing portion 116 and the second wing portion 117 are formed to cover at least the area to which the phosphor ring 109 is attached (details will be described later).

[0033] The first blade section 116 and the second blade section 117 are made up of multiple helical blades arranged in rotationally symmetrical positions on the rotational axis of the base material 108. The first blade section 116 and the second blade section 117 increase the heat dissipation area, and as the base material 108 rotates, an airflow is generated from near the center of the phosphor wheel device 107 toward the outer circumference of the base material 108, promoting heat exchange between the back surface 118 of the base material, the first blade section 116, the second blade section 117 surfaces on the side opposite to the surface where the base material 108 and the phosphor ring 109 are installed, and the air.

[0034] Figure 5 is a rear view of the base material 108 as seen from the back. Figure 6 is a side view of the base material 108 shown in Figure 5. Second wing sections 117 are positioned in the middle of the first wing sections 116, which are arranged at equal intervals in the circumferential direction. Each second wing section 117 is positioned between each wing section of the first wing section 116, and its position is at the center between the wing sections of each first wing section 116. In other words, the first wing sections 116 and the second wing sections 117 are arranged alternately in the circumferential direction. The thickness and height of the second wing sections 117 are set to be smaller than the dimensions of the first wing sections 116.

[0035] Figure 7 is a cross-sectional view showing the phosphor ring 109 placed on the substrate 108. Figure 8 is a rear view of the substrate showing the positional relationship between the phosphor ring 109 (shown by the dashed line in Figure 5) and the first wing portion 116 and the second wing portion 117. Note that Figure 7 represents the cross-section at position B-B in Figure 8.

[0036] As is clear from Figures 7 and 8, the first fin portion 116 and the second fin portion 117 are arranged on the back surface 118 of the substrate that covers the position of the phosphor ring 109. The phosphor ring 109 generates heat when it receives excitation light, and the heat is widely diffused from there. Therefore, it is desirable to cover both the rotation center side (inner diameter portion 120 (inner diameter side edge)) and its outer circumference side (outer diameter portion 121 (outer diameter side edge)) of the phosphor ring 109 with the heat dissipation material, the first fin portion 116 and the second fin portion 117. In other words, it is desirable that the inner diameter portion 120 and the outer diameter portion 121 of the phosphor ring 109 are arranged to intersect with the first fin portion 116 and the second fin portion 117 when the substrate 108 is viewed from the rotation center axis direction.

[0037] In other words, as shown in Figure 8, the phosphor ring 109 is positioned between the radially outer ends of the plurality of first blade portions 116 and the plurality of second blade portions 117 and the radially inner ends of the plurality of first blade portions 116 and the plurality of second blade portions 117.

[0038] As shown in Figure 4, since heat transfer generally has a 45° spreading angle, it is desirable to cover the phosphor ring 109 at least by the thickness t of the base material 108, both inside the inner diameter portion 120 (towards the rotation center) and outside the outer diameter portion 121.

[0039] Next, I will describe the first wing portion 116 and the second wing portion 117.

[0040] Figure 9 is an enlarged view of a key part, which is a magnified portion of Figure 5. On an arbitrary circumference 119 concentric with the outer diameter of the base material 108, virtual circles 306 and 307 are drawn inscribed in the curved portions of the first wing portion 116 and the second wing portion 117, and their diameters are defined here as the diameter (thickness) D1 of the first wing portion 116 and the diameter (thickness) D2 of the second wing portion 117.

[0041] Figure 10 is an enlarged perspective view of a key part, which is an enlarged portion of Figure 5. The main cooling performance of the base material 108 is handled by the first blade section 116, which is the main heat dissipation section. Therefore, the first blade section 116 is optimally designed, and the second blade section 117 is added to further improve performance. The basic design of the first blade section 116 is carried out based on the content disclosed in Japanese Patent Application Publication No. 2023-101526, or by applying thereto, and the final decision is made after conducting temperature simulations, etc. Further performance improvement is achieved by adding the second blade section 117. The parameters for determining the specifications of this second blade section 117 are as follows: - Increasing the surface area of ​​the base material 108 that contributes to heat exchange, - Suppressing inertia within a range commensurate with the performance of the motor 110, - Improving the fin efficiency of the second blade section 117, - Ensuring practical strength.

[0042] To reduce the temperature of the phosphor ring 109, heat dissipation through the substrate 108 is necessary. For this purpose, increasing the surface area, that is, the area in contact with the coolant air, is essential and the most important factor. Regarding the second vane section 117, since the vane is smaller than that of the first vane section 116 due to its auxiliary role, changes in vane thickness have little effect on the surface area, and height is dominant. Therefore, from the viewpoint of surface area, it is desirable to set the vane to a high height.

[0043] While increasing the thickness of the base material 108 increases its surface area, in practice, it is necessary to suppress the inertia, or moment of inertia, within the performance range of the motor 110 that rotates it, and within a range that ensures practical operating conditions and reliability. Inertia is determined by the distance from the center of rotation and the weight distribution, and since it becomes a load on the motor, it is desirable for it to be small and light. For this reason, aluminum alloy A6063 is used as the material for the base material 108 due to its specific gravity, thermal conductivity, and availability. The base material 108 is shaped into the first blade portion 116 and the second blade portion 117 by machining.

[0044] This shape formation is performed, for example, by milling using an end mill. As a processing procedure, for example, a large-diameter end mill is used to dig down between adjacent first blade parts 116 to the top of the second blade part 117 to form a groove. Next, a small-diameter end mill can be used to dig down between the first blade part 116 and the second blade part 117 to simultaneously form the shapes of the first blade part 116 and the second blade part 117.

[0045] The fin efficiency, which is the ease of heat transfer, mainly shows the relationship between the thickness and height of the blades. From the perspective of the above surface area, the blades should be tall, but as they become taller relative to the thickness, heat transfer becomes difficult and the heat dissipation efficiency decreases. Therefore, the height is set to ensure a range where the change in fin efficiency is sensitive to the height. Therefore, from the perspective of fin efficiency, regarding the blades of the second blade part 117, it is desirable that the thickness is thick and the height is appropriately set (including a large change range).

[0046] The base material 108 provided with the phosphor ring 109 is rotated at high speed by the motor 110, so balance adjustment is performed to suppress noise, vibration, and load on the motor 110 at that time. Here, if the blades are partially deformed in the base material 108 before adjustment, it will cause a problem that balance adjustment cannot be performed, and if deformation occurs after balance adjustment, the balance will be disrupted. Specifically, interference with others is considered during transportation or when incorporated into the device. Excluding strong impacts, etc., the base material 108 requires a strength that does not deform with general handling with fins. Therefore, it is desirable to anticipate no deformation under a certain load.

[0047] A specific example of the design shows an examination of the shape that the second blade part 117 should have with respect to the first blade part 116. Here, the outer diameter D0 (see FIG. 5) of the base material 108 is assumed to be φ90 to φ100 mm.

[0048] FIG. 11 is a correlation diagram showing the change rate when the case of only the first blade part 116 is set to 100% on the vertical axis and the ratio (H2 / H1) of the height H2 of the second blade part 117 to the height H1 of the first blade part 116 on the horizontal axis.

[0049] Here, the thickness D2 of the second blade section 117 was fixed to an arbitrary value. The solid line represents the surface area, and the dashed line represents the inertia. From Figure 11, it can be seen that both the surface area and the inertia are directly proportional to the blade height. In the phosphor wheel device 107, the inertia of the first blade section 116 is optimized based on a motor 110 with predetermined performance. Therefore, it is difficult to significantly change the inertia. In other words, we want to avoid increasing the power consumption of the device and also avoid increasing the size of the motor 110. Therefore, in the phosphor wheel device 107, the goal was to keep the inertia below 20%, as shown in Figure 11.

[0050] Figure 12 is a correlation diagram showing the relationship between the thickness D2 of the second blade portion 117 and its inertia. The effect of the thickness of the second blade portion 117 on the surface area is relatively small. Figure 12 shows the inertia for each thickness D2. Note that the vertical and horizontal axes of Figure 12 are the same as in Figure 11. Due to the inertia constraint, for example, if the thickness is 1 mm, the height ratio of the first blade portion 116 will be 0.4 or less. However, returning to Figure 11, it can be seen that with a height ratio of 0.4, the surface area is only 120%. Therefore, from the perspective of surface area and the inertia constraint, the blade thickness D2 of the second blade portion 117 should be 1 mm or less and the height ratio (H2 / H1) should be 0.4 or more. It goes without saying that, as is clear from Figure 12, the constraints on the height ratio differ for each blade thickness.

[0051] Figure 13 is a correlation diagram showing the deflection of the blade tip of the second blade section 117 when a load of 200 gf is applied. Here, the vertical axis represents the amount of deformation. The horizontal axis represents the ratio of the height H2 of the second blade section 117 to the height H1 of the first blade section 116 (H2 / H1). The blade width is shown for six different thicknesses. For the second blade section 117, the amount of change is large when the thickness D2 is 0.4 mm, making it difficult to adopt in terms of strength. However, it seems that it can be adopted if the thickness is increased to about 0.5 mm or more to suppress the blade height ratio. However, although a load of 200 gf is used here, the actual load will vary greatly, so this should be used as a guideline. Specifically, the outer diameter D0 of the base material 108 is preferably φ90 to φ100 mm, and the thickness D2 of the second blade section 117 is preferably 0.5 to 0.6 mm.

[0052] Figure 14 is a correlation diagram showing fin efficiency on the vertical axis and the ratio of the height of the second blade section 117 to the height of the first blade section 116 (H2 / H1) on the horizontal axis. Based on the results obtained from Figure 13, Figure 14 shows the behavior of the second blade section 117 at a blade thickness D2 of 0.4 mm or more. Here, it can be seen that the fin efficiency increases as the blade thickness D2 increases, and the efficiency gradually decreases as the ratio of the height of the second blade section 117 to the height of the first blade section 116 increases. Since the change becomes small at a height ratio above 0.5 to 0.6, it can be seen that even if the blade is taller, a significant improvement in performance cannot be expected. From this, it is desirable that the blade height of the second blade section 117 be 50 to 60% of that of the first blade section 116.

[0053] In summary, the following is desirable for the outer diameter D0 of the base material 108 when it is between φ90 and φ100 mm: Surface area, inertia: fin height H2 ≥ 0.4 × H2 / H1, D2 ≤ 1 mm Strength: D2 ≥ 0.5 mm Fin efficiency: 0.5 × H1 ≤ H2 ≤ 0.6 × H1 Therefore, the result is that 0.5 mm ≤ D2 ≤ 0.6 mm and 0.5 × H1 ≤ H2 ≤ 0.6 × H1 are desirable.

[0054] It is also possible that the height H1 of the first blade portion 116 is not uniform from the rotation center side end to the outer circumference side end of the base material 108, but the above relationship still holds true on the same circumference. Furthermore, it is also possible that the thickness of the first blade portion 116 is not uniform, and the thickness increases from the rotation center side end to the outer circumference side end of the base material 108, but the above relationship still holds true on any circumference in that configuration as well.

[0055] In the above explanation, the phosphor ring 109 is made of ceramic formed by sintering a phosphor. Its excellent thermal conductivity is advantageous for obtaining fluorescence properties even under high-power excitation light conditions. On the other hand, under conditions where the light output is kept at a constant value and cost is a priority, it is also possible to apply a mixture of phosphor powder and resin binder onto the binder layer containing the filler and then heat-treat it. In this case as well, the relationship between the first blade portion 116 and the second blade portion 117 remains unchanged.

[0056] Next, I will explain the function of the above-described configuration.

[0057] The phosphor wheel device 107 according to Embodiment 1 comprises a disc-shaped base material 108 made of a thermal conductive material, a phosphor ring 109 arranged on one surface of the base material 108, which is concentric with the center O of the disc or as part of a ring, and a motor 110 for rotating the base material 108 around the center of the disc. On the other surface of the base material 108, which is the back surface (back surface 118 of the base material), a plurality of first blade portions 116 and a plurality of second blade portions 117 are provided in a rotationally symmetric manner around the center O of the disc. The second blade portions 117 have a lower blade height H2 perpendicular to the back surface compared to the first blade portions 116, and the thickness D2 in the rotational direction of the base material 108 is thinner.

[0058] In the phosphor wheel apparatus 107 according to Embodiment 1, the light irradiated onto the phosphor ring 109 for excitation, the portion not used as fluorescence, is converted into heat. Much of the heat generated in the phosphor ring 109 is transferred to the substrate 108 by thermal conduction.

[0059] When the heat transferred to the substrate 108 is low in air, it is transferred to the air by heat transfer. This heat transfer involves a combination of heat conduction, heat convection, and heat radiation.

[0060] In other words, the heat from the base material 108 is transferred by heat conduction to the air very close to the first blade portion 116 and the second blade portion 117. Even when the base material 108 is stationary, the nearby air that has stored thermal energy through heat transfer moves to another location by thermal convection. Since the base material 108 rotates, thermal convection is forcibly promoted, and more heat is transferred to the air. At this time, heat is also exchanged between the base material 108 and the nearby air by thermal radiation, but since thermal radiation is an extremely small value, it is ignored here.

[0061] The base material 108 can be referred to as a rotating impeller. As shown in Figure 10, the rotating impeller rotates in the ω direction, causing air to enter mainly from the right side of Figure 10, change direction within the blade row passage, and exit to the lower left of Figure 10. In this case, if there is an area of ​​excessive flow rate within the blade row passage, the flow separates on the pressure surface 308 side of the blades, forming a separation area and vortex accompanied by backflow towards the outlet. This separation and vortex are factors that reduce fluid transport efficiency and heat transfer, and are therefore undesirable in terms of the performance of the rotating impeller. In the phosphor wheel device 107, the inertia is suppressed within the performance range of the motor 110 and within a range that ensures actual operating conditions and reliability, so that the separation and vortex that occur on the pressure surface 308 of the blades are suppressed to be extremely small.

[0062] In the phosphor wheel device 107, the larger the surface area of ​​the first blade portion 116 and the second blade portion 117, the more advantageous it is for heat dissipation to the air. Both surface area and inertia are directly proportional to the blade height. It is desirable to suppress the inertia to a range that is appropriate for the performance of the motor 110. In the phosphor wheel device 107, by setting the ratio of the height H2 of the second blade portion 117 to the height H1 of the first blade portion 116 (H2 / H1) to 1 or less (i.e., making H2 lower than H1), the inertia can be suppressed to a range that is appropriate for the performance of the motor 110.

[0063] Furthermore, the blade thickness D2 of the second blade section 117 is thinner than the blade thickness D1 of the first blade section 116. This reduces the weight of the base material and the inertia compared to a configuration where the blade thickness D2 of the second blade section 117 is the same as the blade thickness D1 of the first blade section 116, thus reducing the motor load.

[0064] Furthermore, in terms of fluid transport efficiency, since the height H2 is lower than the height H1, a greater airflow can be secured within the blade row passage compared to the case where the heights H2 and H1 are the same. In addition, since the thickness D2 of the base material 108 is thinner than the thickness D1, a greater airflow can be secured within the blade row passage compared to the case where the thicknesses D2 and D1 are the same.

[0065] As a result, the phosphor wheel device 107 enables the realization of a phosphor and its configuration that efficiently converts incident light, as well as a cooling means that can achieve this inexpensively. Consequently, the heat generated in the phosphor can be efficiently cooled with a simple configuration.

[0066] In the phosphor wheel device 107, the phosphor ring 109 has an inner diameter portion 120 and an outer diameter portion 121 that are covered by the first blade portion 116 and the second blade portion 117.

[0067] In this phosphor wheel device 107, the inner diameter portion 120 and the outer diameter portion 121 of the phosphor ring 109, which are on the rotation center side, are covered by the first blade portion 116 and the second blade portion 117 of the substrate back surface 118. The phosphor ring 109 generates heat when it receives excitation light, but the heat is widely diffused from that point. Therefore, by covering the inner diameter portion 120 and the outer diameter portion 121 of the phosphor ring 109 with the first blade portion 116 and the second blade portion 117 of the substrate back surface 118, heat transfer can be carried out without hindrance and heat can be efficiently dissipated.

[0068] In general, heat has a 45° spreading angle, so in the case of a substrate 108 with a thickness t, it is more desirable to cover the phosphor ring 109 at least by the thickness t of the substrate 108, both inside the inner diameter portion 120 (towards the rotation center) and outside the outer diameter portion 121.

[0069] In the phosphor wheel device 107, the second blade section 117 has a blade height H2 that is 50-60% of that of the first blade section 116.

[0070] In this phosphor wheel device 107, the fin efficiency increases with increasing blade thickness D2, and gradually decreases as the ratio of the height of the second blade section 117 to the height of the first blade section 116 increases. The change becomes small at height ratios above 0.5 to 0.6, so significant performance improvement cannot be expected even if the blades are taller. For this reason, it is desirable that the blade height of the second blade section 117 be 50 to 60% of that of the first blade section 116.

[0071] In the phosphor wheel device 107, the outer diameter D0 of the base material 108 is φ90 to φ100 mm, and the thickness D2 of the second blade portion 117 is 0.5 to 0.6 mm.

[0072] In this phosphor wheel device 107, if the thickness D2 of the second blade portion 117 is 0.4 mm, the amount of change becomes large, making it difficult to adopt in terms of strength. On the other hand, if the second blade portion 117 is made thicker than about 0.5 mm to suppress the blade height ratio, it can be adopted. However, although a load of 200 gf was used here, the actual load will vary greatly, so this should be used as a guideline. In other words, when the outer diameter D0 of the base material 108 is φ90 to φ100 mm, it is desirable that the thickness D2 of the second blade portion 117 be 0.5 to 0.6 mm.

[0073] In the phosphor wheel device 107, the second blade portion 117 is positioned in the center between the adjacent first blade portions 116.

[0074] In this phosphor wheel device 107, a plurality of first blade sections 116 are provided at equal intervals on the base material 108. Second blade sections 117, which are shorter in height than the first blade sections 116, are positioned in the center between adjacent first blade sections 116. As a result, two types of blade row passages with different spacings can be formed circumferentially on the back surface 118 of the base material, along the rotational axis.

[0075] In the phosphor wheel apparatus 107, a layer containing a filler 112, which has a higher reflectivity and better thermal conductivity than the substrate 108, is provided between the phosphor ring 109 and the substrate 108.

[0076] In this phosphor wheel device 107, the phosphor ring 109 emits light without directionality. The fluorescence emitted from the phosphor ring 109 towards the substrate 108 is reflected by the filler 112 in the adhesive layer 111 before reaching the substrate 108, and re-incidentates to the phosphor ring 109. The re-incident light passes through the adhesive layer 111 and is emitted from the surface side of the phosphor ring 109. This makes it possible to increase the efficiency of fluorescence utilization.

[0077] In the phosphor wheel apparatus 107, the layer containing the filler 112 is an adhesive layer 111 containing the filler.

[0078] In this phosphor wheel device 107, a filler 112 is mixed into a transparent adhesive layer 111 so that it is diffusely distributed. The phosphor ring 109 is fixed to the substrate 108 by this adhesive layer 111. The filler 112 has a higher thermal conductivity than the material of the adhesive layer 111 and higher light reflection properties than the substrate 108, thus possessing these properties. In other words, since the space between the phosphor ring 109 and the substrate 108 contains the filler 112, which has a higher reflectivity and superior thermal conductivity than the substrate 108, the fluorescence emitted from the phosphor ring 109 towards the substrate 108 can be reflected back to the phosphor ring 109. Furthermore, since the phosphor wheel device 107 fixes the phosphor ring 109 to the substrate 108 with an adhesive layer 111 containing the filler 112, it can achieve the same performance at a lower cost compared to forming a reflective layer on the substrate surface by vapor deposition or the like.

[0079] In the phosphor wheel apparatus 107, the phosphor ring 109 is made of ceramic.

[0080] In this phosphor wheel device 107, the phosphor ring 109 is made of ceramic. That is, the phosphor ring 109 is formed as a ceramic phosphor by firing and hardening the phosphor. By using a ceramic phosphor, the durability and heat resistance of the phosphor ring 109 can be improved. The ceramic phosphor is fixed to the phosphor ring mounting surface 301 of the base material 108 by an adhesive layer 111 containing the filler 112 mentioned above.

[0081] In the phosphor wheel device 107, the base material 108 is made by machining aluminum alloy A6063.

[0082] In this phosphor wheel device 107, by using aluminum alloy A6063 for the base material 108, it is possible to achieve weight reduction, improved thermal conductivity, processability, and availability.

[0083] The lighting device 201 according to Embodiment 1 includes a phosphor wheel device 107, a blue optical path system 300 that emits blue light from a light source 202, and a phosphor ring 109 that emits yellow fluorescence. It also includes a dichroic mirror 207 that superimposes the blue light emitted from the blue optical path system 300 and the yellow fluorescence emitted from the phosphor ring 109 on the same optical axis.

[0084] The illumination device 201 according to Embodiment 1 is configured by adding a blue light path system 300 and a dichroic mirror 207 to the illumination device 100 (see Figure 2). The illumination device 201 allows the blue light emitted from the blue light path system 300 and the yellow fluorescence emitted from the phosphor ring 109 provided on the illumination device 100 to be superimposed on the same optical axis by the dichroic mirror 207 and incident onto the lens 113.

[0085] The projection-type image display device 200 according to Embodiment 1 includes an illumination device 201, a relay optical system 208 that sequentially directs light from the illumination device 201, a total internal reflection prism 213, and a color prism unit 218.

[0086] In the projection-type image display device 200 according to Embodiment 1, blue light and yellow light emitted from the lens 113 of the illumination device 201 are incident on the relay optical system 208. As a result, the projection-type image display device 200 can achieve high output and high reliability using the illumination device 201.

[0087] Therefore, according to the phosphor wheel device 107, lighting device 201, and projection-type image display device 200 of Embodiment 1, heat generated in the phosphor can be efficiently cooled with a simple configuration.

[0088] Although Figure 1 shows a configuration using three DMDs, it goes without saying that this can also be applied to a three-panel liquid crystal system where blue and yellow light are used to modulate the liquid crystal panels for blue, green, and red. Furthermore, it can also be applied to a single-panel system where phosphors with different characteristics are arranged to change the color of light emitted over time, and the signal driving one DMD is switched according to the illumination timing of that color to obtain a color display on the screen.

[0089] (Summary of this disclosure) Based on the above description of embodiments, the following technical concepts corresponding to the items below are disclosed.

[0090] (Item 1) A phosphor wheel device comprising: a disc-shaped substrate made of a thermal conductive material; a phosphor ring disposed on one surface of the substrate, which is concentric with the center of the disc, either as an annular ring or as part of an annular ring; and a motor that rotates the substrate around a rotation center axis passing through the center of the disc, wherein a plurality of first blades and a plurality of second blades are provided on the other surface of the substrate, which is the back surface, in a rotationally symmetrical manner around the center of the disc, and the second blades have a lower blade height in the direction of the rotation center axis compared to the first blades, and the thickness of the substrate in the rotation direction is thinner.

[0091] (Item 2) The phosphor wheel device according to Item 1, wherein the inner diameter side edge and the outer diameter side edge of the phosphor ring intersect with the first blade portion and the second blade portion when the substrate is viewed in the direction of the rotation center axis. As a result, the phosphor wheel device can efficiently dissipate heat without hindrance of heat transfer because the inner diameter portion and the outer diameter portion of the phosphor ring are covered by the first blade portion and the second blade portion on the back surface of the substrate.

[0092] (Item 3) The phosphor wheel device according to Item 1 or 2, wherein the height of the second blade portion is 50 to 60% of that of the first blade portion. This allows the phosphor wheel device to efficiently cool the heat generated in the phosphor with a simple configuration under practically adoptable standards.

[0093] (Item 4) A phosphor wheel device according to any one of items 1 to 3, characterized in that the outer diameter of the base material is φ90 to φ100 mm, and the thickness of the second blade portion is 0.5 to 0.6 mm. As a result, the phosphor wheel device can efficiently cool the heat generated in the phosphor with a simple configuration under practically applicable standards.

[0094] (Item 5) The phosphor wheel device according to any one of Items 1 to 4, wherein the second blade portion is positioned at the center between adjacent first blade portions. This makes it possible to form two types of blade row passages with different spacings in the circumferential direction on the back surface of the substrate of the phosphor wheel device, along the rotational axis.

[0095] (Item 6) A phosphor wheel device according to any one of Items 1 to 5, wherein a layer containing a filler having a higher reflectivity and superior thermal conductivity than the substrate is provided between the phosphor ring and the substrate. This allows the phosphor wheel device to increase the efficiency of fluorescence utilization.

[0096] (Item 7) The phosphor wheel device according to Item 6, wherein the layer containing the filler is an adhesive layer containing the filler. This allows the phosphor wheel device to reflect the fluorescence emitted from the phosphor ring in the direction of the substrate and return it to the phosphor ring.

[0097] (Item 8) The phosphor wheel device according to any one of Items 1 to 7, wherein the phosphor ring is made of ceramic. This allows the phosphor wheel device to improve the durability and heat resistance of the phosphor ring.

[0098] (Item 9) The phosphor wheel device described in any one of Items 1 to 8, wherein the base material is made by machining aluminum alloy A6063. This makes the phosphor wheel device lighter, more heat-conductive, easier to process, and more readily available.

[0099] (Item 10) A lighting device comprising: a phosphor wheel device described in any one of Items 1 to 9; a blue optical path system that emits blue light from a light source; and the phosphor ring that emits yellow fluorescence, wherein the lighting device is equipped with a dichroic mirror that superimposes the blue light emitted from the blue optical path system and the yellow fluorescence emitted from the phosphor ring on the same optical axis. This enables the lighting device to realize a phosphor and its configuration that efficiently converts incident light, and a cooling means that can realize this at low cost. As a result, the heat generated in the phosphor can be efficiently cooled with a simple configuration.

[0100] (Item 11) A projection-type image display device comprising: an illumination device described in Item 10; a relay optical system for sequentially injecting light from the illumination device; a total internal reflection prism; and a color prism unit. This enables the projection-type image display device to realize a phosphor and its configuration that efficiently converts incident light, as well as a cooling means that can realize this at low cost. As a result, the heat generated in the phosphor can be efficiently cooled with a simple configuration.

[0101] While embodiments have been described above with reference to the attached drawings, this disclosure is not limited to such examples. It is clear to those skilled in the art that various modifications, alterations, substitutions, additions, deletions, and equivalents can be conceived within the scope of the claims, and these are also understood to fall within the technical scope of this disclosure. Furthermore, the components of the embodiments described above can be combined in any way without departing from the spirit of the invention.

[0102] This disclosure is applicable to lighting devices using phosphor wheels and projection-type image display devices that use them as lighting units.

[0103] 107...Phosphor wheel device 108...Substrate 109...Phosphor ring 110...Motor 111...Adhesive layer 112...Filler 116...First blade section 117...Second blade section 118...Back surface of substrate (other side) 120...Inner diameter section (inner end) 121...Outer diameter section (outer end) 200...Projection type image display device 201...Illumination device 202...Light source 207...Dichroic mirror 208...Relay optical system 213...Total internal reflection prism 218...Color prism unit 300...Blue light path system 301...Phosphor ring mounting surface (one side, surface) O...Center of the disc

Claims

1. A phosphor wheel device comprising: a disc-shaped base material made of a thermal conductive material; a phosphor ring disposed on one surface of the base material, which is concentric with the center of the disc, either as an annular ring or as part of an annular ring; and a motor for rotating the base material around a rotation axis passing through the center of the disc, wherein a plurality of first blades and a plurality of second blades are provided on the other surface of the base material, which is the back surface, in a rotationally symmetrical manner around the center of the disc, and the second blades have a lower blade height in the rotation axis direction and a thinner thickness in the rotation direction of the base material compared to the first blades.

2. The phosphor wheel device according to claim 1, wherein the inner diameter side edge and the outer diameter side edge of the phosphor ring intersect with the first blade portion and the second blade portion when the substrate is viewed in the direction of the rotation center axis.

3. The phosphor wheel device according to claim 1, wherein the height of the second blade portion is 50 to 60% of that of the first blade portion.

4. The phosphor wheel device according to claim 1, wherein the outer diameter of the base material is φ90 to φ100 mm, and the thickness of the second blade portion is 0.5 to 0.6 mm.

5. The phosphor wheel device according to claim 1, wherein the second blade portion is positioned at the center between adjacent first blade portions.

6. The phosphor wheel apparatus according to claim 1, wherein a layer containing a filler having a higher reflectivity and superior thermal conductivity than the substrate is provided between the phosphor ring and the substrate.

7. The phosphor wheel apparatus according to claim 6, wherein the layer containing the filler is an adhesive layer containing the filler.

8. The phosphor wheel apparatus according to claim 1, wherein the phosphor ring is made of ceramic.

9. The phosphor wheel device according to claim 1, wherein the base material is made by machining aluminum alloy A6063.

10. A lighting device comprising: a phosphor wheel device according to any one of claims 1 to 9; a blue optical path system that emits blue light from a light source; and the phosphor ring that emits yellow fluorescence, wherein the device includes a dichroic mirror that superimposes the blue light emitted from the blue optical path system and the yellow fluorescence emitted from the phosphor ring on the same optical axis.

11. A projection-type image display device having the illumination device described in claim 10, comprising a relay optical system for sequentially injecting light from the illumination device, a total internal reflection prism, and a color prism unit.

Images