Projection-type image display device

Abstract

To provide a phosphor wheel in which imbalance in mass distribution is reduced.SOLUTION: A phosphor wheel 10 includes a disc-shaped substrate 20 having a first main surface 21, a second main surface 22 opposite to the first main surface 21, and an opening 23, and a phosphor layer that is provided on the first main surface 21 in a curved shape along the circumferential direction of the substrate 20, and is positioned in parallel to the opening 23 in the circumferential direction in a planar view. On the second main surface 22, a heat dissipation fin 25 and a protrusion 26 in a different form from the heat dissipation fin 25 are integrally formed with the substrate 20.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a phosphor wheel included in a field-sequential projection-type image display device.

Background Art

[0002] A field-sequential projector including a wavelength conversion device called a phosphor wheel is known (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a phosphor wheel with a reduced imbalance in mass distribution.

Means for Solving the Problems

[0005] A phosphor wheel according to an aspect of the present disclosure includes a disk-shaped substrate having a first main surface, a second main surface opposite to the first main surface, and an opening, and a phosphor layer provided in a curved shape along the circumferential direction of the substrate on the first main surface, the phosphor layer being positioned side by side with the opening in a plan view, and a heat dissipation fin and a convex portion having a different aspect from the heat dissipation fin are integrally formed with the substrate on the second main surface. [[ID=4​​​​​​​​​

[0007] [Figure 1] Figure 1 shows the configuration of a projection-type image display device according to an embodiment. [Figure 2] Figure 2 shows a view of the color filter of the projection-type image display device according to the embodiment, as seen from the light incident side. [Figure 3] Figure 3 is a plan view of the phosphor wheel according to the embodiment, as seen from the first main surface side. [Figure 4] Figure 4 is a plan view of the phosphor wheel according to the embodiment, as seen from the second main surface side. [Figure 5] Figure 5 is a perspective view of the phosphor wheel according to the embodiment, as seen from the second main surface side. [Figure 6] Figure 6 is a plan view of the phosphor wheel according to the comparative example, as seen from the first main surface side. [Figure 7] Figure 7 is a plan view of the phosphor wheel according to the comparative example, as seen from the second main surface side. [Figure 8] Figure 8 is a plan view of the phosphor wheel according to Modification 1, as seen from the first main surface side. [Figure 9] Figure 9 is a plan view of the phosphor wheel according to Modification 1, as seen from the second main surface side. [Figure 10] Figure 10 is a plan view of the phosphor wheel according to the modified example 2, as seen from the second main surface side. [Figure 11] Figure 11 is a perspective view of the phosphor wheel according to Modification 2, as seen from the second main surface side. [Figure 12] Figure 12 is a perspective view of the phosphor wheel according to Modification 3, as seen from the second main surface side. [Modes for carrying out the invention]

[0008] [Knowledge that forms the basis of this disclosure] A field-sequential projection-type image display device that uses a digital micromirror device (DMD), an image display element capable of high-speed response, to sequentially switch the light of each of the RGB colors to achieve color display of an image has been put on the market.

[0009] Patent Document 1 discloses a field-sequential projection-type display device. The projection-type display device includes a color wheel (color filter) that sequentially and rapidly switches the color light of RGB, and the color wheel is provided with a space part without a color filter. In order to adjust the weight balance due to the formation of the space part, a balance weight is provided on the central member of the color wheel.

[0010] Further, Patent Document 2 discloses a field-sequential projector. The projector includes a wavelength conversion device. The wavelength conversion device (hereinafter also described as a phosphor wheel) includes a disk having a first surface and a second surface, a wavelength conversion element provided on the first surface, and a heat sink separate from the base material provided on the second surface. In such a wavelength conversion device, a balance adjustment member may be arranged to adjust the rotational balance of the disk.

[0011] By the way, when an opening is provided in the phosphor wheel, there is room for study on a method for reducing the imbalance in the mass distribution caused by the opening. The method of attaching a separate member as in Patent Documents 1 and 2 may be useful when finely adjusting the imbalance in the mass distribution, but is not suitable when the opening is relatively large. In this specification, a phosphor wheel found in view of such problems is disclosed.

[0012] Hereinafter, embodiments will be specifically described with reference to the drawings. Note that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, steps, order of steps, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0013] Moreover, each figure is a schematic diagram and is not necessarily drawn precisely. In each figure, substantially the same configuration is denoted by the same reference numeral, and redundant descriptions may be omitted or simplified.

[0014] (Embodiment) [Configuration of Projection-Type Image Display Device] Hereinafter, a projection-type image display device according to an embodiment will be described. FIG. 1 is a diagram showing the configuration of the projection-type image display device according to the embodiment. In FIG. 1, the right direction is defined as the positive X-axis direction, the upward direction is defined as the positive Y-axis direction, and the direction toward the front side of the paper surface is defined as the positive Z-axis direction.

[0015] As shown in FIG. 1, the projection-type image display device 100 includes laser light sources 104a, 104b, 104c, condenser lenses 105, 106, a diffuser plate 107, a dichroic mirror 108, excitation lenses 109, 110, a phosphor wheel 10, a motor 113, relay lenses 132, 134, 136, 138, mirrors 133, 135, 137, a diffuser plate 139, a condenser lens 118, a color filter 119, a motor 120, a rod integrator 124, relay lenses 125, 126, folding mirrors 127, 128, a DMD 129, and a projection lens 130.

[0016] The laser light sources 104a, 104b, and 104c emit blue light to excite the phosphor layer of the phosphor wheel 10. In other words, the laser light sources 104a, 104b, and 104c irradiate the phosphor layer with blue light. Blue light is, for example, monochromatic light with a central wavelength of 455 nm in its emission spectrum. The laser light sources 104a, 104b, and 104c are realized, for example, by semiconductor lasers.

[0017] Each of the laser light sources 104a, 104b, and 104c is equipped with a collimating lens at its output port and emits blue parallel light forward (in the positive X-axis direction). The emitted blue parallel light is incident on the focusing lens 105, and the light focused by the focusing lens 105 is incident on the focusing lens 106. The focusing lens 106 is a concave lens. The blue parallel light emitted by the laser light sources 104a, 104b, and 104c is converted into parallel light with a smaller diameter by the focusing lens 106, and then incident on the diffuser plate 107.

[0018] The diffuser plate 107 improves the uniformity of parallel blue light by diffusing the parallel blue light incident on the diffuser plate 107. The light that passes through the diffuser plate 107 is incident on the dichroic mirror 108.

[0019] The dichroic mirror 108 has the property of transmitting blue light and reflecting visible light that emits colors other than blue light. Since the light that has passed through the diffuser plate 107 is blue light, it passes through the dichroic mirror 108 and is focused by the excitation lenses 109 and 110 to form a focused spot on the phosphor wheel 10.

[0020] As described later, in the phosphor wheel 10, the red phosphor layer, the green phosphor layer, and the aperture are located on the same circumference, and the light-gathering spot is formed on this circumference. The red phosphor layer emits red fluorescence when irradiated with blue light, and the green phosphor layer emits green fluorescence when irradiated with blue light. When the phosphor wheel 10 is rotated by the motor 113, the red fluorescence is emitted toward the dichroic mirror 108, the green fluorescence is emitted toward the dichroic mirror 108, and the blue light passes toward the relay lens 132 in sequence.

[0021] The red and green fluorescence emitted from the phosphor wheel 10 passes through excitation lenses 109 and 110 and enters the dichroic mirror 108. As described above, the dichroic mirror 108 has the property of reflecting visible light other than blue light, so it reflects the red and green fluorescence, and the reflected red and green fluorescence passes through the focusing lens 118 and enters the color filter 119.

[0022] Meanwhile, the blue light passing through the aperture in the phosphor wheel 10 is diffused by the diffuser plate 139 via a relay optical path for blue light, which consists of relay lenses 132, 134, 136, 138 and mirrors 133, 135, 137. The diffused blue light passes through the dichroic mirror 108 and enters the color filter 119 after passing through the focusing lens 118.

[0023] In this manner, red fluorescence, green fluorescence, and blue light are incident on the color filter 119 in sequence. Figure 2 shows the color filter 119 as viewed from the light incident side. As shown in Figure 2, the color filter 119 includes a red transmission filter 121 that selectively transmits only red light, a green transmission filter 122 that selectively transmits only green light, and a transparent glass 123 that has been treated with an anti-reflective coating.

[0024] The center of the color filter 119 is fixed to the motor hub of the motor 120, and the color filter 119 rotates in synchronization with the phosphor wheel 10 by the motor 120. Specifically, the system is synchronized so that red fluorescence is incident on the red transmission filter 121, green fluorescence is incident on the green transmission filter 122, and blue light is incident on the transparent glass 123. The red transmission filter 121 removes unwanted wavelength components contained in the red fluorescence, and the green transmission filter 122 removes unwanted wavelength components contained in the green fluorescence. This achieves the desired color purity.

[0025] In this way, red light, green light, and blue light are emitted from the color filter 119 in a time-division manner. The light emitted from the color filter 119 enters the rod integrator 124, undergoes repeated total internal reflection within the rod integrator 124, and then exits the rod integrator 124. The light emitted from the rod integrator 124 enters the DMD 129 via relay lenses 125, 126, and folding mirrors 127, 128.

[0026] The DMD129 is an example of an image display element that modulates light emitted from the phosphor wheel 10 (phosphor layer) in response to laser light irradiated by laser light sources 104a, 104b, and 104c based on an image signal. The DMD129 includes a base and a plurality of micromirrors provided on the base.

[0027] The tilt angle of each of the multiple micromirrors is changed either or either based on the image signal. Specifically, the tilt angle of each of the multiple micromirrors is selectively changed to either a first tilt angle that directs the light incident on the micromirror toward the projection lens 130, or a second tilt angle that directs the light incident on the micromirror toward a direction other than the projection lens 130.

[0028] The DMD129 projects a red image to the projection lens 130 based on the R signal of the image signal when red light is incident on it, a green image to the projection lens 130 based on the G signal of the image signal when green light is incident on it, and a blue image to the projection lens 130 based on the B signal of the image signal when blue light is incident on it. In other words, the operation of the DMD129 is synchronized with the phosphor wheel 10 and the color filter 119, and the red, green, and blue images are switched at high speed.

[0029] The projection lens 130 projects light (i.e., an image) modulated by the DMD 129. The projection lens 130 displays a color image on the screen.

[0030] Alternatively, a reflective liquid crystal panel (LCOS: Liquid Crystal On Silicon) may be used as the image display element instead of the DMD129. Furthermore, the projection-type image display device 100 may include a transmissive image display element, such as a transmissive liquid crystal panel, instead of the reflective image display elements such as the DMD129 and the reflective liquid crystal panel.

[0031] As explained above, the projection-type image display device 100 can display color images.

[0032] [Phosphor Wheel Composition] Next, the structure of the phosphor wheel 10 will be described in detail. Figure 3 is a plan view of the phosphor wheel according to the embodiment as seen from the first main surface side. Figure 4 is a plan view of the phosphor wheel according to the embodiment as seen from the second main surface side. Figure 5 is a perspective view of the phosphor wheel according to the embodiment as seen from the second main surface side. The first main surface is the main surface of the phosphor wheel 10 on the dichroic mirror 108 side, and the second main surface is the main surface on the opposite side from the first main surface. In the following embodiments, the radial direction of a circle centered on a virtual rotation axis J (shown in Figures 3 to 5) is described as the radial direction r (shown in Figures 3 and 4), and the circumferential direction of a circle centered on the rotation axis J is described as the circumferential direction θ (shown in Figure 5).

[0033] As shown in Figures 3 to 5, the phosphor wheel 10 comprises a substrate 20 and a phosphor layer 30. The phosphor wheel 10 is an optical component used in a projection-type image display device 100. The phosphor layer 30 of the phosphor wheel 10 emits light when irradiated with laser light. At this time, half of the energy is converted into heat, but when the phosphor particles contained in the phosphor layer 30 reach a certain temperature or higher, the conversion efficiency decreases and the amount of heat generated increases. When the amount of heat generated increases, concerns arise about reliability, such as the deterioration of the resin material contained in the phosphor layer 30.

[0034] Therefore, in order to avoid concentrating the laser beam on a single point in the phosphor layer 30, the phosphor wheel 10 rotates around the rotation axis J by the motor 113 while the phosphor layer 30 is being irradiated with laser light. This prevents the same area of ​​the phosphor layer 30 from being continuously irradiated with laser light. In other words, it prevents the degradation of the phosphor particles contained in the phosphor layer 30 due to heat generation. Furthermore, the substrate 20 is made of a thermally conductive material such as aluminum, which enhances the heat dissipation of the phosphor layer 30.

[0035] The substrate 20 is a disc-shaped substrate centered on the axis of rotation J. In other words, the shape of the substrate 20 in plan view is circular. The shape in plan view is, in other words, the shape when viewed from a direction perpendicular to the first main surface 21 (or second main surface 22) of the substrate 20. The substrate 20 has a first main surface 21, a second main surface 22 opposite to the first main surface 21, and an opening 23.

[0036] Furthermore, a main opening 24 is provided in the center of the substrate 20, and a rotor of a motor (not shown in Figures 3 to 5) is connected to the main opening 24. A rotation axis J passes through the center (center position) of the substrate 20, and the substrate 20 is rotated around the rotation axis J by the motor. The substrate 20 is formed of, for example, aluminum, an aluminum-containing alloy, or a metal with good thermal conductivity such as copper.

[0037] A phosphor layer 30 is provided on the first main surface 21 of the substrate 20. The phosphor layer 30 is curved along the circumferential direction θ of the substrate 20. That is, the phosphor layer 30 is arc-shaped. The phosphor layer 30 is located alongside the opening 23 in the circumferential direction θ. In other words, the phosphor layer 30 and the opening 23 are located on the same circumference. Furthermore, in the phosphor wheel 10, the width of the phosphor layer 30 in the radial direction r is constant, and the width of the phosphor layer 30 in the radial direction r is the same as the width of the opening 23 in the radial direction r.

[0038] The phosphor layer 30 specifically comprises a red phosphor layer 30r and a green phosphor layer 30g. The red phosphor layer 30r is formed from a resin material containing a large number of red phosphor particles. The red phosphor particles are specifically CaAlSiN3:Eu 2+ Alternatively, (Sr,Ca)AlSiN3:Eu 2+ And so on. The red phosphor layer 30r may also contain phosphor particles that emit fluorescence of colors other than red.

[0039] The 30g green phosphor layer is formed from a resin material containing numerous green phosphor particles. Specifically, the green phosphor particles are Y3(Al,Ga)5O 12 :Ce 3+ , or Lu3Al5O 12 :Ce 3+ And so on. Note that the 30g green phosphor layer may also contain phosphor particles that emit fluorescence of colors other than green.

[0040] The resin material base is, for example, a light-transmitting and thermosetting silicone resin. The phosphor layer 30 is formed, for example, by bonding a cured resin material containing separately produced phosphor particles to the substrate 20 with a light-reflective adhesive. The adhesive is formed from, for example, a resin binder containing titanium oxide and also functions as a light-reflective layer. The phosphor layer 30 may also be formed by screen printing the uncured resin material containing phosphor particles onto the first main surface 21 of the substrate 20, and then heat-curing it in a heating furnace. Although not shown in Figures 3 to 5, a light-reflective film may be provided between the first main surface 21 of the substrate 20 and the phosphor layer 30.

[0041] The red phosphor layer 30r and the green phosphor layer 30g are both curved along the circumferential direction θ, and one end of each is connected along the circumferential direction θ. In a plan view, an aperture 23 is located between the other end of the red phosphor layer 30r and the other end of the green phosphor layer 30g, and the aperture 23 is also curved along the circumferential direction θ. The aperture 23 is a through-hole for transmitting laser light (blue light).

[0042] With this configuration, the phosphor wheel 10 can time-resolved inject red, green, and blue light into the DMD 129.

[0043] It is not essential that the phosphor layer 30 includes a red phosphor layer 30r and a green phosphor layer 30g; the phosphor layer 30 may be a single yellow phosphor layer formed from a resin material containing a large number of yellow phosphor particles. The yellow phosphor particles are, for example, YAG-based yellow phosphor particles. Even with such a phosphor layer 30, the color filter 119 can be used in combination to allow red, green, and blue light to be incident on the DMD 129 in a time-resolved manner.

[0044] To improve the heat dissipation of the phosphor layer 30, a plurality of heat dissipation fins 25 are provided on the second main surface 22 of the substrate 20. The plurality of heat dissipation fins 25 are provided over almost the entire second main surface 22 of the substrate 20. In a plan view, each of the plurality of heat dissipation fins 25 is arc-shaped and not centered on the axis of rotation J, and the plurality of heat dissipation fins 25 as a whole form a vortex shape. However, it is not essential that the plurality of heat dissipation fins 25 form a vortex shape. The plurality of heat dissipation fins 25 may be arranged in any way, such as radially. The arrangement of the plurality of heat dissipation fins 25 may be determined empirically or experimentally as appropriate.

[0045] Multiple heat dissipation fins 25 are integrally formed with the substrate 20 (more specifically, the main body of the substrate 20) by, for example, cutting the substrate of the substrate 20. Cutting is performed, for example, with a tool such as an end mill, but may also be performed with a laser. Multiple heat dissipation fins 25 have cutting marks.

[0046] Furthermore, the second main surface 22 of the substrate 20 is provided with protrusions 26 in a different manner from the heat dissipation fins 25. While the multiple heat dissipation fins 25 as a whole have a vortex shape, the protrusions 26 have a curved shape along the circumferential direction θ (in other words, an arc shape centered on the axis of rotation J). Similar to the multiple heat dissipation fins 25, the protrusions 26 are formed integrally with the substrate 20 by cutting the substrate material of the substrate 20. The protrusions 26 have cutting marks.

[0047] The protrusion 26 is provided to reduce the imbalance (moment imbalance) in the mass distribution of the phosphor wheel 10 caused by the presence of the opening 23. In other words, the protrusion 26 is positioned such that the imbalance in the mass distribution of the phosphor wheel 10 caused by the presence of the opening 23 is reduced.

[0048] Specifically, the protrusion 26 is located on the outer periphery of the opening 23 and is positioned parallel to the opening 23 in the radial direction r. In this way, if the protrusion 26 is located in a region on the outer periphery of the opening 23, the imbalance in mass distribution caused by the opening 23 can be reduced by the protrusion 26 having a mass less than the mass reduced by the opening 23. In other words, it is possible to reduce the imbalance in mass distribution while suppressing an increase in the overall weight. Furthermore, if the protrusion 26 is curved along the opening 23, the area around the opening 23 can be structurally reinforced. The mass of the protrusion 26 is determined by the height of the protrusion 26, the length of the protrusion 26 in the circumferential direction θ, and the width of the protrusion 26 in the radial direction r. The height of the protrusion 26 is, in other words, the length of the protrusion 26 in the direction perpendicular to the second main surface 22.

[0049] By adjusting the position and mass of the protrusions 26, the residual unbalance of the phosphor wheel 10 is kept below the allowable residual unbalance. The design residual unbalance can be set to zero.

[0050] Incidentally, in the phosphor wheel 10, the area 27 surrounding the aperture 23 of the second main surface 22 is flat, and no heat dissipation fins 25 or protrusions 26 are provided in the surrounding area 27. This suppresses the stray light (unwanted light) or heat source that occurs when laser light passing through the aperture 23 hits the multiple heat dissipation fins 25 and protrusions 26. The maximum width of the protrusions 26 in the radial direction r is limited so that the laser light passing through the aperture 23 does not hit them. If the laser light does not hit the multiple heat dissipation fins 25 and protrusions 26, the multiple heat dissipation fins 25 and protrusions 26 may extend to the vicinity of the end face of the aperture 23.

[0051] Furthermore, the height of the protrusion 26 may differ from the height of the heat dissipation fin 25, but in the phosphor wheel 10, the height of the protrusion 26 is the same as the height of the heat dissipation fin 25. If the height of the protrusion 26 is the same as the height of the heat dissipation fin 25, multiple heat dissipation fins 25 and protrusions 26 can be formed in the same cutting process. In other words, the manufacturing process of the phosphor wheel 10 (substrate 20) can be simplified and costs can be reduced. When the height of the protrusion 26 and the height of the heat dissipation fin 25 are the same, the mass of the protrusion 26 can be adjusted mainly by its length in the circumferential direction θ.

[0052] The advantages of the phosphor wheel 10 will be explained below in comparison with the phosphor wheel of the comparative example. Figure 6 is a plan view of the phosphor wheel of the comparative example as seen from the first main surface side, and Figure 7 is a plan view of the phosphor wheel of the comparative example as seen from the second main surface side.

[0053] The phosphor wheel 10h shown in Figures 6 and 7 comprises a substrate 20h on which a phosphor layer 30 is provided on a first main surface 21h and a plurality of heat dissipation fins 25h are provided on a second main surface 22h. The substrate 20h also has an opening 23h. To reduce the imbalance in the mass distribution of the phosphor wheel 10h caused by the provision of the opening 23h, the substrate 20h also has an opening 26h.

[0054] Thus, in order to reduce the imbalance in mass distribution by the opening 26h, the opening 26h needs to be located on the opposite side of the rotation axis J from the opening 23h and in a position that does not overlap with the phosphor layer 30. Therefore, due to space constraints, the opening 26h is located on the inner circumference side of the phosphor layer 30. In order to eliminate the imbalance in mass distribution, the opening 26h needs to be formed larger than the opening 23h. If the opening 26h is large, disadvantages may arise such as a deterioration in the flatness of the area on the first main surface 21h where the phosphor layer 30 is provided, and a decrease in the heat capacity of the substrate 20h, resulting in poor heat dissipation.

[0055] In contrast, with the phosphor wheel 10, the imbalance in the mass distribution of the phosphor wheel 10 is reduced by the protrusions 26, thereby suppressing deterioration of the flatness of the first main surface 21 and deterioration of heat dissipation.

[0056] [Example 1] If there are concerns about a decrease in the strength of the substrate 20 due to the long circumferential length θ of the opening 23, the length of one opening in the circumferential direction θ can be shortened by providing two or more openings. Figure 8 is a plan view of the phosphor wheel according to such modified example 1, as seen from the first main surface side. Figure 9 is a plan view of the phosphor wheel according to modified example 1, as seen from the second main surface side. In modified example 1, explanations of matters similar to those for the phosphor wheel 10 are omitted as appropriate, and the explanation focuses on the differences from the phosphor wheel 10.

[0057] The phosphor wheel 10a shown in Figures 8 and 9 comprises a substrate 20a on which a phosphor layer 30a is provided on a first main surface 21a and a plurality of heat dissipation fins 25a are provided on a second main surface 22a. The substrate 20a is also provided with two openings 23a.

[0058] The red phosphor layer 30r and the green phosphor layer 30g contained in the phosphor layer 30a are located alongside the two openings 23a in the circumferential direction θ. In other words, the red phosphor layer 30r, the green phosphor layer 30g, and the two openings 23a are located on the same circumference.

[0059] The second main surface 22a is provided with two protrusions 26a corresponding to the two openings 23a. Each of the two protrusions 26a is curved along the circumferential direction θ, located on the outer circumference side of the corresponding opening 23a, and positioned alongside the corresponding opening 23a in the radial direction r.

[0060] Thus, when two openings 23a are provided in the substrate 20a, the imbalance in the mass distribution of the phosphor wheel 10a can be reduced by providing a protrusion 26 on the outer circumference of each of the two openings 23a.

[0061] [Differentiation 2] Furthermore, when two openings 23a are provided in the substrate 20a, as in the phosphor wheel 10a, it is not essential that two protrusions 26a be provided. In other words, the number of openings 23a and the number of protrusions do not have to match. Figure 10 is a plan view of the phosphor wheel according to Modification 2 as seen from the second main surface side. Figure 11 is a perspective view of the phosphor wheel according to Modification 2 as seen from the second main surface side. In Modification 2, explanations of matters similar to those of phosphor wheels 10 and 10a are omitted as appropriate, and the explanation focuses on the differences from phosphor wheel 10.

[0062] The plan view of the phosphor wheel 10b shown in Figures 10 and 11, as seen from the first main surface 21b side, is the same as that of Figure 8. In other words, the configuration of the first main surface 21b side of the phosphor wheel 10b is the same as that of the phosphor wheel 10a. Multiple heat dissipation fins 25b are provided on the second main surface 22b of the substrate 20b of the phosphor wheel 10b. In addition, two openings 23b are provided on the substrate 20b.

[0063] The second main surface 22b is provided with one protrusion 26b relative to the two openings 23b. The protrusion 26b is curved along the circumferential direction θ and is located in a region midway between the two openings 23a, on the outer periphery side of the two openings 23b.

[0064] Thus, when two apertures 23b are provided in the substrate 20b, the imbalance in the mass distribution of the phosphor wheel 10b can be reduced by providing one protrusion 26b in the region between the two apertures 23b. If the protrusion 26b is positioned to avoid the vicinity of the apertures 23b, the laser light passing through the apertures 23b will not hit the protrusion 26b, which would result in stray light (unwanted light) or a heat source, thus suppressing this.

[0065] [Difference 3] In the phosphor wheels 10, 10a, and 10b, the shape of the protrusions was curved (in other words, arc-shaped) along the circumferential direction θ, but the shape of the protrusions is not particularly limited. Figure 12 is a perspective view of the phosphor wheel according to Modification 3, viewed from the second main surface side. In Modification 3, explanations of matters similar to those of the phosphor wheel 10 are omitted as appropriate, and the explanation focuses on the differences from the phosphor wheel 10.

[0066] A plan view of the phosphor wheel 10c according to Modification 3, as seen from the first main surface 21c side, is the same as in Figure 5, and therefore its illustration and description are omitted. The substrate 20c of the phosphor wheel 10c is provided with an opening 23c. Multiple heat dissipation fins 25c are provided on the second main surface 22c of the substrate 20c.

[0067] Furthermore, the second main surface 22c of the substrate 20 is provided with a plurality of protrusions 26c in a manner different from that of the heat dissipation fins 25c. Each of the plurality of protrusions 26c is dot-shaped. The plurality of protrusions 26 are located on the outer periphery side of the opening 23, and each of the plurality of protrusions 26c is positioned alongside the opening 23c in the radial direction r. In addition, the plurality of protrusions 26c are positioned along the circumferential direction θ.

[0068] In this way, the imbalance in the mass distribution of the phosphor wheel 10c can also be reduced by the multiple dot-shaped protrusions 26c.

[0069] [Effects, etc.] As described above, the phosphor wheel 10 comprises a disc-shaped substrate 20 having a first main surface 21, a second main surface 22 opposite to the first main surface 21, and an opening 23, and a phosphor layer 30 provided on the first main surface 21 in a curved shape along the circumferential direction θ of the substrate 20, and the phosphor layer 30 being positioned in line with the opening 23 in the circumferential direction θ in a plan view. A heat dissipation fin 25 and a protrusion 26 having a different configuration from the heat dissipation fin 25 are integrally formed with the substrate 20 on the second main surface 22.

[0070] This allows the protrusions 26 to reduce the imbalance in the mass distribution of the phosphor wheel 10. In other words, the phosphor wheel 10 can be said to be a phosphor wheel in which the imbalance in mass distribution is reduced by the protrusions 26.

[0071] Furthermore, for example, the protrusion 26 is located in the region of the second main surface 22 that is on the outer periphery side of the opening 23.

[0072] This allows the imbalance in mass distribution caused by the opening 23 to be reduced by the protrusion 26, which has a mass less than the mass reduced by the opening 23.

[0073] Furthermore, for example, the protrusion 26 is located alongside the opening 23 in the radial direction of the substrate 20.

[0074] This allows the protrusion 26 to structurally reinforce the area around the opening 23.

[0075] Furthermore, for example, the convex portion 26 is formed in a curved shape along the circumferential direction θ.

[0076] This allows the protrusion 26 to structurally reinforce the area around the opening 23.

[0077] Furthermore, for example, the height of the protrusion 26 is the same as the height of the heat dissipation fin 25.

[0078] This allows multiple heat dissipation fins 25 and protrusions 26 to be formed in the same cutting process.

[0079] Furthermore, for example, the protrusion 26 is formed in a position that reduces the imbalance in the mass distribution of the phosphor wheel 10 caused by the opening 23.

[0080] This allows the protrusions 26 to reduce the imbalance in the mass distribution of the phosphor wheel 10.

[0081] Furthermore, for example, the residual unbalance of the phosphor wheel 10 is less than or equal to the allowable residual unbalance.

[0082] This results in a phosphor wheel 10 in which the residual unbalance is less than or equal to the allowable residual unbalance.

[0083] Furthermore, for example, the area 27 surrounding the opening 23 of the second main surface 22 is flat.

[0084] This prevents the laser light passing through the aperture 23 from hitting the multiple heat dissipation fins 25 and protrusions 26, thus suppressing the occurrence of stray light (unwanted light) or heat sources.

[0085] Furthermore, for example, the heat dissipation fins 25 and the protrusions 26 are formed by cutting.

[0086] This allows the heat dissipation fins 25 and the protrusions 26 to be formed by cutting.

[0087] Furthermore, in the phosphor wheel 10b, the substrate 20b has multiple openings 23b, and one protrusion 26b is provided for each of the multiple openings 23b, thereby reducing the imbalance in the mass distribution of the phosphor wheel 10b.

[0088] This allows the protrusion 26b to be positioned at a distance from the multiple apertures 23b, thereby suppressing the occurrence of stray light (unwanted light) or heat generation from laser light passing through the apertures 23b hitting the protrusion 26b.

[0089] Furthermore, in the phosphor wheel 10c, the protrusions 26c are formed in a dot-like pattern along the circumferential direction θ.

[0090] This allows the imbalance in the mass distribution of the phosphor wheel 10c to be reduced by the multiple dot-shaped protrusions 26c, each of which are dot-shaped.

[0091] Furthermore, the projection-type image display device 100 includes a phosphor wheel 10, a motor 113 for rotating the phosphor wheel 10, laser light sources 104a, 104b, and 104c for irradiating the phosphor layer 30 with laser light, a DMD 129 for modulating the light emitted from the phosphor layer 30 in response to the laser light irradiated by the laser light sources 104a, 104b, and 104c based on an image signal, and a projection lens 130 for projecting the light modulated by the DMD 129. The DMD 129 is an example of an image display element. The projection-type image display device 100 may also include phosphor wheels 10a, 10b, and 10c instead of the phosphor wheel 10.

[0092] Such a projection-type image display device 100 is made more reliable by incorporating a phosphor wheel 10 in which the imbalance in mass distribution is reduced.

[0093] (Other embodiments) Although embodiments have been described above, this disclosure is not limited to the embodiments described above.

[0094] For example, in the above embodiment, the protrusion is positioned on the outer circumference side of the substrate relative to the opening, but it may also be positioned on the inner circumference side of the substrate relative to the opening.

[0095] Although embodiments have been described above, the present invention is not limited to the embodiments described above.

[0096] Furthermore, although the laser light source was described as a semiconductor laser in the above embodiment, it may be a laser other than a semiconductor laser. The laser light source may be, for example, a solid-state laser such as a YAG laser, a liquid laser such as a dye laser, or a gaseous laser such as an Ar ion laser, He-Cd laser, nitrogen laser, or excimer laser.

[0097] Furthermore, the general or specific aspects of this disclosure may be implemented as a system, apparatus, or method. For example, this disclosure may be implemented as a method for manufacturing a phosphor wheel. Such a manufacturing method includes the steps of creating a substrate by cutting and forming a phosphor layer on the created substrate.

[0098] Furthermore, the present invention also includes forms obtained by applying various modifications to each embodiment and its variations as conceived by those skilled in the art, as well as forms realized by arbitrarily combining the components and functions of the embodiments without departing from the spirit of the present invention. [Industrial applicability]

[0099] This disclosure is useful as a phosphor wheel used in field sequential projection image display devices. [Explanation of Symbols]

[0100] 10, 10a, 10b, 10c, 10h Phosphor Wheel 20, 20a, 20b, 20c, 20h substrate 21, 21a, 21b, 21c, 21h First principal surface 22, 22a, 22b, 22c, 22h Second principal surface 23, 23a, 23b, 23c, 23h, 26h opening 24 Main opening 25, 25a, 25b, 25c, 25h heat dissipation fins 26, 26a, 26b, 26c protrusions 27 areas 30, 30a Phosphor layer 30g green phosphor layer 30r Red Phosphor Layer 100 Projection-type image display device 10⁴a, 10⁴b, 10⁴c Laser light source 105, 106, 118 Focusing lenses 107, 139 Diffuser 108 Dichroic Mirror 109, 110 Excitation Lens 113, 120 motor 119 Color Filters 121 Red Transmittance Filter 122 Green Transmittance Filter 123 Transparent glass 124 Rod Integrator 125, 126, 132, 134, 136, 138 Relay Lens 127, 128, 133, 135, 137 Miller 130 projection lens J rotation axis r radial direction θ Circumferential direction

Claims

1. A phosphor wheel having a phosphor layer, A motor for rotating the phosphor wheel, A laser light source that irradiates the phosphor layer with laser light, An image display element that modulates light emitted from the phosphor layer in response to laser light irradiated by the laser light source based on an image signal, The system comprises a projection lens that projects light modulated by the image display element, The aforementioned phosphor wheel is A first main surface, a second main surface opposite to the first main surface, and a disc-shaped substrate having an opening, The second main surface is provided with heat dissipation fins arranged in a spiral or radial pattern to cool the heated phosphor layer, The second main surface side comprises a protrusion positioned alongside the opening in the radial direction of the substrate and formed along the circumferential direction of the substrate, The phosphor layer is provided on the first main surface of the substrate along the circumferential direction of the substrate, and is positioned in a plan view of the substrate alongside the opening and in the circumferential direction. The heat dissipation fins are formed on the second main surface side such that the laser light passing through the opening does not strike the heat dissipation fins. Projection-type image display device.

2. The aforementioned protrusion is located in the region of the second main surface that is on the outer periphery side of the opening. The projection-type image display device according to claim 1.

3. The aforementioned protrusion is formed in a curved shape along the circumferential direction. The projection-type image display device according to claim 1 or 2.

4. The aforementioned protrusions are formed in a dot-like pattern along the circumferential direction. The projection-type image display device according to claim 1 or 2.

5. The height of the aforementioned protrusion is the same as the height of the heat dissipation fin. A projection-type image display device according to any one of claims 1 to 4.

6. The protrusion is formed in a position that reduces the imbalance in the mass distribution of the phosphor wheel caused by the opening. A projection-type image display device according to any one of claims 1 to 5.

7. A phosphor wheel having a phosphor layer, A motor for rotating the phosphor wheel, A laser light source that irradiates the phosphor layer with laser light, An image display element that modulates light emitted from the phosphor layer in response to laser light irradiated by the laser light source based on an image signal, The system comprises a projection lens that projects light modulated by the image display element, The aforementioned phosphor wheel is A disc-shaped substrate having a first main surface, a second main surface opposite to the first main surface, and a plurality of openings, The second main surface is provided with heat dissipation fins arranged in a spiral or radial pattern to cool the heated phosphor layer, It comprises a protrusion formed on the second main surface side, provided such that the imbalance in the mass distribution of the phosphor wheel is reduced with respect to the plurality of openings, The phosphor layer is provided on the first main surface of the substrate along the circumferential direction of the substrate, and is positioned in a plan view of the substrate alongside the opening and in the circumferential direction. The heat dissipation fins are formed on the second main surface side such that the laser light passing through the opening does not strike the heat dissipation fins. Projection-type image display device.

8. The heat dissipation fins and the protrusions are formed by cutting. A projection-type image display device according to any one of claims 1 to 7.

Images