Abstract:
There is provided a manufacturing method of a color wheel for a projector. The method includes contacting a phosphor layer contour correcting device on a surface of a color wheel substrate, the phosphor layer contour correcting device having a concavity to form a space that patterns a desired phosphor layer contour, the length of which is constant in a radial direction; injecting phosphor additive resin into the space that is composed of a surface of the color wheel substrate and the concavity of the phosphor layer contour correcting device; maintaining the phosphor additive resin in the space; and heating the phosphor additive resin.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a color wheel for a projector that projects and enlarges a display image by means of a projection optical system so as to obtain a large display image, and the manufacturing method of the color wheel. The present invention also relates to a projector that includes the color wheel in its projection optical system. 
         [0003]    2. Description of the Related Art 
         [0004]    A projector (a projection-type image display device) used in home theaters, presentations, etc. in which to magnify and project displayed images by means of a projection optical system so as to obtain large-screen displayed images has been commercialized. This type of projector displays, while applying light that is projected from a light source as an illuminant, images on a screen through an electro-optical device using a spatial optical modulator such as a digital micromirror device or a liquid crystal display device. The projector may use a high-pressure mercury vapor lamp or a xenon lamp as the light sources. Due to content of mercury or problems caused by calorific values, the high-pressure mercury vapor lamp or the xenon lamp appears to be not appropriate. Accordingly, in recent years a projector applying a light emitting diode (LED) or a laser has been developed. 
         [0005]    For example, as the projector using the LED and the laser, a projector manufactured by Casio Computer Co., Ltd. has been exhibited at the International CES (Consumer Electronics Show), the trade show of consumer electronics, held in the United States in 2010. Here, an LED is used for a red illuminant; a blue laser is used for a blue illuminant; and what the phase and the wavelength of a blue laser is converted is used for a green illuminant (this type of projector is hereinafter called as the “hybrid type”). Further, in this type of projector, a color wheel as the time-sharing type of a filter device that rotates at a high speed has been generally applied (see Japanese Patent Application Laid-Open No. 2009-277516 and Japanese Patent Application Laid-Open No. 2004-341105). 
         [0006]    In a color composite method regarding the above hybrid type projector,  FIG. 8  shows the schematic diagram thereof. In  FIG. 8 , a projector  100  has the following components as the projection optical system: a blue illuminant  1 , a red illuminant  2 , a color wheel  5 , dichroic mirrors  3 ,  8 , lenses  4 ,  9 , mirrors  6 ,  7 , a digital micromirror device  10  as a spatial optical modulator, a projection optical system  11 , and a screen  12 . Blue light (B) emitted from the blue illuminant  1  to which a blue laser emitter is applied is irradiated on the color wheel  5  after passing through the dichroic mirror  3  and the lens  4  that the blue light permeates. As shown in  FIGS. 9A and 9B , the color wheel  5  has a metal circular substrate  501  with a cutout. The surface of the circular substrate  501  is then divided into a portion  502  on which a phosphor layer that emits green light (G) (hereinafter referred to as the “green phosphor”) is formed, and a portion  503  where the green phosphor is not provided, The blue light passes through the portion (cutout portion)  503  where the green phosphor is not provided, and permeates the dichroic mirror  8 . The blue light is then condensed by the lens  9  and finally reaches to the digital micromirror device  10 . 
         [0007]    A partial blue light (BR) that has been reflected from the color wheel  5  goes back to the side of the blue illuminant  1 . When the blue light is irradiated on the green phosphor, the green light is to be emitted. This green light is then passed through the lens  4  and reflected by the dichroic mirror  3 , which reflects the green light. The green light is then reflected by the mirrors  6 ,  7  and the dichroic mirror  8 , and collected by the lens  9  so as to reach to the digital micromirror device  10 . 
         [0008]    In addition, red light (R) emitted from the red illuminant  2  to which red LED is applied passes through the dichroic mirror  3  and is reflected by the mirrors  6 ,  7  and the dichroic mirror  8 . The red light (R) is then collected by the lens  9  and reaches to the digital micromirror device  10 . In three primary colors of the blue light (B), the green light (G) and the red light (R) that are introduced into the digital micromirror device  10 , their incident lights are converted in synchronization so that the three primary colors are processed in time series to produce images of each own color. The images are then projected on the screen  12  through the projection optical system  11 . Here, the rotation control of the color wheel  5  or the control of light passing through the color wheel  5  is a conventional technology. Explanation thereof is thus omitted. 
         [0009]    Here, considering the above-described hybrid type projector where the color wheel  5  is included in its projection optical system, in order to optimize the chromaticity of projected images, it would be preferable to minimize the occurrence of non-uniform chromaticity of the green light (G) that is reflected by the portion  502  on which the green phosphor layer is formed. On the other hand, since the green phosphor generates heat by which the blue laser light is received, it would be preferable that the component (hereinafter referred to as the “phosphor additive resin”) of the green phosphor layer is resin having high heat resistance and superior light permeability. The phosphor additive resin is generally coated on the glass-made circular substrate  501  by means of dispenser or printing methods. In case that the viscosity of the phosphor additive resin is low after being coated on the circular substrate  501 , as shown in  FIG. 9B , the phosphor additive resin tends to spread on the surface of the circular substrate  501  whereby the thickness thereof becomes uneven. When making the thickness of the phosphor additive resin become uneven, the thickness of phosphors becomes non-uniform, becoming one cause of making the adjustment of its chromaticity difficult. To overcome the above problem, for example, resin with high viscosity (or resin enhancing its thixotrophy) may be used. With this, it can reduce the spread of resin after being coated on the substrate; however, in general, since the resin having high heat resistance and superior light permeability has low viscosity, it will cause a problem that the durability of a color wheel is deteriorated. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention has been made in light of the above problems, and it is an object of the present invention to provide a color wheel for a projector capable of preventing the occurrence of irregular colors while maintaining its durability. Further, another object of the present invention is to improve the chromaticity of a projector that includes a color wheel in its projection optical system such as a hybrid type projector. 
         [0011]    Embodiments according to the present invention hereinbelow exemplify some structures of the present invention, and are itemized for facilitating understanding of various structures of the present invention. Each item does not intend to limit the technical scope of the present invention. While considering the best modes to carry out the present invention, even if components of each item is partially substituted or deleted, or even if another component is added thereto, these should be regarded as the elements of the technical scope of the present invention. 
         [0012]    In order to achieve the object described above, according to a first aspect of the present invention, there is provided a manufacturing method of a color wheel for a projector, comprising the steps of: contacting a phosphor layer contour correcting device on a surface of a color wheel substrate, the phosphor layer contour correcting device having a concavity to form a space that patterns a desired phosphor layer contour, the length of which is constant in a radial direction; injecting phosphor additive resin into the space that is composed of a surface of the color wheel substrate and the concavity of the phosphor layer contour correcting device; maintaining the phosphor additive resin in the space; and heating the phosphor additive resin. 
         [0013]    With this manufacturing method of the color wheel, the phosphor additive resin is injected into the space formed between the surface of the color wheel substrate and the concavity of the phosphor layer contour correcting device. The phosphor additive resin, being fluid in a pre-thermosetting status, is corrected to have a desired phosphor layer configuration where its thickness is constant in a radius direction. The phosphor layer is then sealed. While maintaining the sealing condition of the phosphor layer, the phosphor additive resin is heated so as to be thermoset. 
         [0014]    In the first aspect of the present invention, in the process of heating the phosphor additive resin, the phosphor additive resin is subjected to temporal heat; the phosphor layer contour correcting device is removed as necessary; and the phosphor additive resin that has been subjected to the temporal heat is then fully heated. 
         [0015]    With this manufacturing method of the color wheel, in the process of heating the phosphor additive resin, by making the phosphor additive resin temporally heated at first, the phosphor additive resin is temporarily thermoset. Accordingly, the phosphor additive resin by itself is allowed to keep a desired phosphor layer configuration where the thickness thereof is constant in its radius direction. Following the step, as necessary, after the phosphor layer contour correcting device is removed, the phosphor additive resin that has been temporally thermoset is fully heated so as to completely harden the phosphor additive resin. 
         [0016]    In the first aspect of the present invention, the phosphor layer contour correcting device is composed of: a first die having a cavity in which the color wheel substrate is positionable; and a second die that forms a counterpart relative to the first die and that has a cavity which forms a space patterning a desired phosphor layer contour on a surface of the color wheel substrate that has been positioned in the cavity of the first die. 
         [0017]    With this manufacturing method of the color wheel, as the phosphor layer contour correcting device, the first die and the second die are applied. The color wheel substrate is then set to the first die that has the cavity in which the color wheel substrate is positionable. The second die works as a counterpart relative to the first die and has the cavity to form a space patterning the desired phosphor layer contour on the surface of the color wheel substrate positioned in the cavity of the first die. The phosphor additive resin is injected into the space that patterns the desired phosphor layer contour, the space being formed between the surface of the color wheel substrate and the cavity of the second die. The phosphor additive resin is then sealed in the space. 
         [0018]    In the first aspect of the present invention, the following steps are taken: unclamping the first die and the second die; injecting the phosphor additive resin into the cavity of the second die while maintaining the unclamping state; covering the phosphor additive resin that has been injected into the cavity of the second die by means of the color wheel substrate; closing the first die and the second die; and heating the phosphor additive resin. 
         [0019]    With this manufacturing method of the color wheel, in a condition where the first die and the second die are unclamped, the phosphor additive resin is injected into the cavity of the second die at first. Following the step, the phosphor additive resin that has been injected into the cavity of the second die is covered with the color wheel substrate. Then, the first die and the second die are clamped so s to position the color wheel substrate. In a condition where both the first die and the second die are clamped, the phosphor additive resin is injected into the space that patterns the desired phosphor layer contour formed between the surface of the color wheel substrate and the cavity of the second die. The phosphor additive resin is then sealed in the space. 
         [0020]    In the first aspect of the present invention, the following steps are taken: unclamping the first die and the second die; setting the color wheel substrate in the cavity of the first die while maintaining the unclamping state; applying the phosphor additive resin on the surface of the color wheel substrate on which the phosphor layer contour is to be formed; clamping the first die and the second die; filling the phosphor additive resin in the cavity of the second die; and heating the phosphor additive resin. 
         [0021]    With this manufacturing method of the color wheel, in a condition where the first die and the second die are unclamped, the color wheel substrate is first set to the cavity of the first die for positioning. Following the step, the phosphor additive resin is applied on the surface of the color wheel substrate along an area at which the phosphor layer contour is formed. The first die and the second die are then clamped. In a condition where the first die and the second die are clamped, the phosphor additive resin is injected into the space that patterns the desired phosphor layer contour formed between the surface of the color wheel substrate and the cavity of the second die. The phosphor additive resin is then sealed in the space. 
         [0022]    In the first aspect of the present invention, the manufacturing method of the color wheel is satisfied with the following: 1) A non-circular substrate is applied to the color wheel substrate as that at least one segment composing the color wheel is cuttable; 2) The first die is applied to a die that has a cavity in which the non-circular substrate is positionable; 3) The second die is applied to a die that has a cavity by which at least one segment forms a space to pattern a desired phosphor layer contour on a surface of the non-circular substrate that has been positioned in the cavity of the first die; 4) The first die and the second die are clamped; 5) The phosphor additive resin on the surface of the non-circular substrate is thermoset; 6) The non-circular substrate is cut out so as to obtain at least one segment with a desired shape; and 7) The segments are combined to each other so as to form the whole color wheel. 
         [0023]    With this manufacturing method of the color wheel, the second die with the cavity is clamped relative to the surface of a material positioned in the cavity of the first die so as to produce at least one segment, the segment forming a space that patterns the desired phosphor layer contour. The phosphor additive resin is sealed in the space so as to be corrected to have a desired phosphor layer contour where the thickness of the phosphor layer is constant in a radius direction. After the phosphor additive resin on the surface of the material is thermoset (the meaning of “being thermoset” includes hereinafter the process of “being temporally thermoset” or “being fully thermoset”), the material is cut out to have a desired segment formation. By combining the segments, the segment type of color wheel can be formed. In this case, by changing the color of the phosphor layer applied on each segment, it would be possible to obtain a color wheel that has specific different colored segments in a particular proportion, or that has different kinds of the segments. Further, it can provide another advantage that clearly defines the border of each phosphor layer in a different color. 
         [0024]    In the first aspect of the present invention, the phosphor layer contour correcting device has, instead of the second die, a transparent substrate that has a concavity identical with the cavity of the second die, and the transparent substrate is to be left as a component when the color wheel is completed. 
         [0025]    With this manufacturing method of the color wheel, as the phosphor layer contour correcting device, instead of the second die, the transparent substrate with a concave portion identical with the cavity of the second die is used. By clamping the first die and the transparent substrate, a space that patterns a desired phosphor layer contour is formed between the surface of the color wheel substrate and the concave portion of the transparent substrate. The phosphor additive resin is then injected into and sealed in the space. Following the step, the phosphor additive resin on the surface of the color wheel substrate is thermoset so as to obtain the color wheel where the transparent substrate is left as the component of the finished color wheel. Here, the transparent substrate may be any material as long as it has necessary transparency and heat resistance. 
         [0026]    In the first aspect of the present invention, the phosphor layer contour correcting device has, instead of the first die, a flat holder on which the color wheel substrate is placed, the flat holder making the concavity of the transparent substrate to be opened in a direction of a side end face of the color wheel substrate when the flat holder is combined with the transparent substrate; the phosphor additive resin is injected into the side end face of the concavity of the transparent substrate; and the phosphor additive rein is thermoset. 
         [0027]    With this manufacturing method of the color wheel, the flat holder is applied instead of the first die. The phosphor additive resin is injected from the side end face of the concavity of the transparent substrate. The phosphor additive resin is thus sent into the concavity of the transparent substrate thereby correcting the phosphor additive resin to have a desired phosphor layer contour. Here, in case that the viscosity of the phosphor additive resin is low, etc., as necessary, the phosphor additive resin is injected after sealing the side end face of the concavity of the transparent substrate. Following the step, the phosphor additive resin on the surface of the color wheel substrate is thermoset so as to obtain the color wheel where the transparent substrate is left as the component of the finished color wheel. Here, the flat holder may be any material as long as it has necessary heat resistance, 
         [0028]    In the first aspect of the present invention, the phosphor layer contour correcting device has either a transparent substrate that has a concavity identical with the cavity of the second die or a non-transparent substrate that has a concavity identical with the transparent substrate; the phosphor additive resin is subjected to temporal heat; the transparent substrate or the non-transparent substrate is removed; and the phosphor additive resin that has been subjected to temporal heat is then fully heated. 
         [0029]    With this manufacturing method of the color wheel, as regards the phosphor layer contour correcting device, the transparent substrate that has the concavity identical with the cavity of the second die, or the non-transparent substrate that has the concavity identical with the transparent portion is applied. By clamping the first die or the flat holder and the transparent substrate or the non-transparent substrate, the space hat patterns a predetermined phosphor layer contour is formed between the surface of the color wheel substrate and the concavity of either the transparent substrate or the non-transparent substrate. The phosphor additive resin is then injected into and sealed in the space. Following the step, the phosphor additive resin is temporally thermoset until maintaining a desired phosphor layer contour where the thickness thereof is constant in its radius direction, Then, the transparent substrate or the non-transparent substrate is removed, and the phosphor additive resin that has been temporally thermoset is fully heated. Accordingly, the phosphor additive rein is fully thermoset. Here, the non-transparent substrate may be any material as long as it has necessary heat resistance. 
         [0030]    In the first aspect of the present invention, the phosphor layer contour correcting device has a predetermined convexoconcave configuration by which an antireflection structure is formable on a surface of the concavity. 
         [0031]    With this manufacturing method of the color wheel, since the concave portion of the phosphor layer contour correcting device has the surface where the predetermined convexoconcave form working as the anti-reflective structure is formed, it would be possible to transfer the anti-reflective structure to the phosphor additive resin. In general, the application of AR coating for anti-reflective purpose tends to be difficult when applying to soft resin before being thermoset. However, by making the surface of the phosphor additive resin itself to have the anti-reflective structure, it becomes possible to improve application efficiencies of light. 
         [0032]    In a second aspect of the present invention, there is provided a color wheel for a projector produced by the manufacturing method of the color wheel according to any one of the first aspects, wherein a phosphor layer, the thickness of which is constant in a radial direction of the color wheel, is formed at a predetermined area of the color wheel in its circumferential direction. 
         [0033]    In the color wheel for a projector produced by the manufacturing method of the color wheel according to any one of the first aspects, the phosphor layer, the thickness of which is constant in a radius direction of the color wheel, is formed in a predetermined area of the color wheel in its circumferential direction. Accordingly, it would be possible to prevent the occurrence of irregular color in application of the color wheel for a projector. 
         [0034]    In a third aspect of the present invention, there is provided a color wheel for a projector, wherein a phosphor layer, the thickness of which is constant in a radial direction of the color wheel, is formed at a predetermined area of the color wheel in its circumferential direction. 
         [0035]    In the color wheel for a projector, since the phosphor layer, the thickness of which is constant in a radius direction of the color wheel, is formed in a predetermined area of the color wheel in its circumferential direction, it would be possible to prevent the occurrence of irregular color in the color wheel for a projector. 
         [0036]    In a fourth aspect of the present invention, there is provided a projector comprising in its projection optical system: a light source; a lens and the color wheel recited in the second aspect and the third aspect. 
         [0037]    The projector of the above comprises the color wheel for a projector in its projection optical system, the color wheel being formed as that the phosphor layer, the thickness of which is constant in a radius direction of the color wheel, is formed in a predetermined area of the color wheel in its circumferential direction. Accordingly, it would be possible to prevent the occurrence of irregular color in the color wheel for a projector so as to improve the chromaticity of images projected on a projector. 
         [0038]    Since the present invention is structured as discussed hereinabove, it makes possible to provide a color wheel where durability of the color wheel for a projector is not deteriorated while occurrence of irregular color can be prevented. Further, the present invention can surely contribute to improvement of chromaticity of a projector where a color wheel is included in its projection optical system such as the hybrid type projector, etc. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0039]      FIG. 1  is an explanatory view of the manufacturing method of a color wheel according to the first embodiment of the present invention where FIG IA is a sectional view showing that a first die and a second die are clamped each other, and  FIG. 1B  is a plan view of the color wheel; 
           [0040]      FIG. 2  is an explanatory view of the manufacturing method of a color wheel according to the second embodiment of the present invention where  FIG. 2A  is a sectional view showing that a first die and a second die are clamped each other, and  FIG. 2B  is a plan view of the color wheel; 
           [0041]      FIG. 3  is an explanatory view of the manufacturing method of a color wheel according to the third embodiment of the present invention where  FIG. 3A  is a sectional view showing that a first die and a second die are clamped each other;  FIG. 3B  is a plan view where phosphor additive resin on the surface of a non-circular substrate is thermoset; and 
           [0042]      FIG. 3C  is a plan view of the color wheel; 
           [0043]      FIG. 4  is a sectional view of the manufacturing method of a color wheel according to the fourth embodiment of the present invention showing that a transparent substrate and a flat holder are clamped each other; 
           [0044]      FIG. 5  is an explanatory view of the manufacturing method of a color wheel according to the fifth embodiment of the present invention where  FIGS. 5A  to SC show the manufacturing procedure of forming convexoconcave working as an anti-reflective structure on phosphor additive resin of the color wheel, and  FIGS. 5D to 5F  exemplify kinds of the convexoconcave; 
           [0045]      FIGS. 6A to 6F  are explanatory drawings in relation with some optical features of the color wheel for a projector according to the embodiments of the present invention; 
           [0046]      FIGS. 7A to 7F  are explanatory drawings in relation with some optical features of the color wheel for a projector according to the embodiments of the present invention; 
           [0047]      FIG. 8  is the conventional schematic drawing of a hybrid-type projector; and 
           [0048]      FIG. 9A  is a schematic plan diagram showing a conventional color wheel for a projector, and  FIG. 9B  is the side view thereof where phosphor additive resin is applied on the color wheel as that the thickness of the phosphor additive resin is not uniform in the radius direction of the color wheel. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0049]    Embodiments of the present invention will be explained with reference to the accompanying drawings. Hereinbelow, any part that is identical with or correspondent to the conventional art will be indicated with the same reference, and the detail explanation thereof will be omitted. Further, noted that a color wheel for a projector according to embodiments of the present invention is applicable to a hybrid-type projector as exemplified in  FIG. 8 . Accordingly, the detail explanation of the projector as a whole should be referred to  FIG. 8 . 
         [0050]    Here, a color wheel substrate  501  composing a color wheel  5  (including a non-circular substrate  511  in  FIG. 3 ) is made of glass; however, the material is not limited to glass. For example, as explained in the conventional art, when a reflective optical system is applied, the material may be metal. Further, phosphor material applied to a phosphor layer  504  may be the following. For example, as phosphor for a green illuminant, the following may be named: Zn 2 SiO 4 : Mn, BaAl 12 O 19 : Mn, BaMgAl 14 O 23 : Mn, SrAl 12 O 19 : Mn, ZnAl 12 O 19 : Mn, CaAl 12 O 19 : Mn, YBO 3 : Tb, LuBO 3 : Tb, GdBO 3 : Tb, ScBO 3 : Tb, Sr 4 Si 3 O 8 Cl 4 : Eu. Furthermore, as phosphor for a red illuminant, the following may be named: Y 2 O 3 : Eu, Y 2 SiO 5 : Eu, Y 3 Al 5 O 12 : Eu, Zn 3  (PO 4 ) 2 : Mn, YBO 3 : Eu, (Y, Gd) BO 3 : Eu, GdBO 3 : Eu, ScBO 3 : Eu, LuBO 3 : Eu. 
         [0051]    First, the manufacturing method of a color wheel for a projector according to the first embodiment of the present invention will be explained. Schematically, as shown in  FIG. 1A , a phosphor layer contour correcting device  20  is employed, the phosphor layer contour connecting device  20  having a concavity by which a space A is formable on the surface of the color wheel substrate  501 . A desired phosphor layer contour, the thickness of which is constant in the radius direction of the color wheel substrate  501 , can be thus obtained. Phosphor additive resin  504  is then injected into and sealed in the space A formed between the surface of the color wheel substrate  501  and the concavity of the phosphor layer contour correcting device  20 . In this condition, the phosphor additive resin  504  is heated. Here, the phosphor additive resin  504  may be first temporarily heated by, for example, a heater built-in the phosphor layer contour correcting device  20 . Then, as necessary, after the phosphor layer contour correcting device  20  has been removed, the phosphor additive resin  504  that has been temporarily thermoset is introduced into a furnace, etc. so as to be fully thermoset. Through these processes, the color wheel  5  as shown in  FIG. 1B  can be obtained. 
         [0052]    More specifically, as the phosphor layer contour correcting device  20 , the following dies are applied: a first die  22  that has a cavity  22   a  in which the color wheel substrate  501  is positionable; and a second die  24  that forms a counterpart relative to the first die  22  and that has a cavity  24   a  which forms the space A patterning a desired phosphor layer contour on the surface of the color wheel substrate  501  that has been positioned in the cavity of the first die  22 . 
         [0053]      FIG. 1  exemplifies a case that the first die  22  is an upper die while the second die  24  is a lower die. The color wheel  501  has a circular opening at its center so as to be in an annular configuration. In a condition where the first die  22  and the second die  24  are unclamped, the phosphor additive resin  504  is injected into the cavity  24   a  of the second die  24 . The phosphor additive resin  504  that has been injected into the cavity  24   a  of the second die  24  is then covered by the color wheel substrate  501 . Following the step, the first die  22  and the second die  24  are clamped as shown in  FIG. 1A , and the phosphor additive resin  504  is heated. Here, the first die  22  exemplified in FIG. I has the concave cavity  22   a  for which the color wheel substrate  501  is positioned; however, if the cavity  24   a  of the second die  24  allows the color wheel substrate  510  to be securely positioned, it would be possible that the portion of the first die  22  to which the color wheel substrate  510  is abutted may be flat (meaning that the depth of the cavity  22   a  is zero). 
         [0054]    According to the first embodiment of the present invention that has the above constitution, the following operational effects are obtainable. That is, by injecting the phosphor additive resin  504  into the space A formed between the surface of the color wheel substrate  501  and the concavity of the phosphor layer contour correcting device  20 , the phosphor additive resin  504 , being fluid in a pre-thermosetting status, is corrected to have a desired phosphor layer contour, the thickness of which is constant in the radius direction of the color wheel substrate  501 . The phosphor additive resin  504  is then sealed. Here, although detail is explained hereinafter, the constant thickness of the phosphor additive resin  504  is corrected to be the minimum. While being sealed, the phosphor additive resin  504  is temporarily thermoset. Accordingly, the phosphor additive resin  504  by itself is adapted to keep a desired phosphor layer configuration where its thickness in a radius direction is constant. After the phosphor layer contour correcting device  20  is removed, the phosphor additive resin  504  that has been temporarily thermoset is fully heated to achieve a fully thermosetting state. 
         [0055]    As the phosphor layer contour correcting device  20 , the first die  22  and the second die  24  are applied. The color wheel substrate  501  is set in the cavity  22   a  of the first die  22 . The surface of the color wheel substrate  501  that has been set to the first die  22  and the cavity  24   a  of the second die  24  will form the space A patterning a predetermined phosphor layer configuration. The phosphor additive resin  504  is then injected into and sealed in the space A. Here, the second die  24  is a counterpart relative to the first die  22  and has the cavity  24   a  which forms the space A patterning a predetermined phosphor layer configuration on the surface of the color wheel substrate  501  that has been positioned in the cavity  22   a  of the first die  22 . 
         [0056]    In this case, in a condition that the first die  22  and the second die  24  are unclamped, the phosphor additive rein  504  is first injected into the cavity  24   a  of the second die  24 . Then, the phosphor additive resin  504  that has been injected into the cavity  24   a  of the second die  24  is covered by the color wheel substrate  501 . Following the step, the first die  22  and the second die  24  are clamped. The color wheel  501  is positioned by the cavity  22   a  of the first die  22 . While being clamped, the phosphor additive rein  504  is injected into and sealed in the space A patterning a desired phosphor layer configuration that is formed by the surface of the color wheel substrate  501  and the cavity  24   a  of the second die  24 . Finally, as shown in  FIG. 1B , the color wheel  5  for a projector can be obtained. In the color wheel  5 , the phosphor additive resin  504 , the thickness of which is constant in the radius direction of the color wheel  501 , is formed at a predetermined area of the color wheel  501  in its circumferential direction (all-rounded area in case of FIGS.). 
         [0057]    In case of the first embodiment of the present invention, when using the phosphor additive resin  504  that has relatively high viscosity, contrary to the case of  FIG. 1 , the first die  22  may be a lower die while the second die  24  may be an upper die. Specifically, in a condition that the first die  22  and the second die  24  are unclamped, the color wheel  501  is set to the cavity  22   a  of the first die  22 . The phosphor additive resin  504  is then injected into the cavity  24   a  of the second die  24 . Following the step, the first die  22  and the second die  24  are clamped. By injecting the phosphor additive resin  504  into the cavity  24   a  of the second die  24  and by heating the phosphor additive resin  504 , it would be possible to obtain operational effects identical with the above case. 
         [0058]    Next, with reference to  FIG. 2 , the second embodiment of the present invention will be hereinafter explained. Here, parts identical with the prior art or the first embodiment of the present invention will be indicated with the same referential number, and the detail explanation thereof will be omitted. 
         [0059]    In the second embodiment of the present invention, the first die  22  is a lower die, and the second die  24  is an upper die. In a condition where the first die  22  and the second die  24  are unclamped, the color wheel substrate  501  is set to the cavity  22   a  of the first die  22 . The phosphor additive resin  504  is applied by means of appropriate methods on the surface of the color wheel substrate  501  on which a predetermined phosphor layer configuration should be formed. When applying the phosphor additive resin  504 , its viscosity should be considered. Following the step, the first die  22  and the second die  24  are clamped. The phosphor additive resin  504  is then filled in the cavity  24   a  of the second die  24 . The phosphor additive resin  504  is subsequently heated. In the second embodiment, as shown in  FIG. 2 , the second die  24  is intentionally abutted to the upper face of the peripheral end portion of the color wheel substrate  501  whereby the layer of the phosphor additive resin  504  is formed to stay slightly inside than the outer peripheral end of the color wheel substrate  501  in a radius direction. With this constitution, even if a space is generated between the color wheel substrate  501  and the second die  24  due to difference in thermal expansion or dimensional accuracy therebetween, it makes possible to prevent the phosphor additive resin  504  having low viscosity from going round toward the backside of the color wheel substrate  501  where resin should not be applied. 
         [0060]    In the second embodiment of the present invention, in a condition where the first die  22  and the second die  24  are unclamped, the color wheel  501  is first set to the cavity  22   a  of the first die  22  for positioning. Next, the phosphor additive resin  504  is applied on the surface of the color wheel substrate  501  on which the phosphor layer configuration should be formed. The first die  22  and the second die  24  are then clamped. While being in the clamped condition, the phosphor additive resin  504  is sealed in the space A patterning a predetermined phosphor layer configuration that is formed between the surface of the color wheel substrate  501  and the cavity  24   a  of the second die  24 . With the above steps, it would be possible to obtain operational effects that are the same with the first embodiment. Further, as shown in  FIG. 2B , the color wheel  5  for a projector can be obtained. In the color wheel for a piston  5 , the phosphor additive resin  504 , the thickness of which is constant in the radius direction of the color wheel  501 , is formed at a predetermined area of the color wheel  501  in its circumferential direction (all-rounded area in case of FIGS.). Here, the other operation effects identical with the first embodiments of the present invention will be omitted in its detail. 
         [0061]    Next, with reference to  FIG. 3 , the third embodiment of the present invention is explained hereinafter. Here, portions identical with the prior art, the first embodiment or the second embodiment are indicated with the same referential numbers, and the detail explanation thereof is omitted. 
         [0062]    In the third embodiment of the present invention, the non-circular substrate  511  is employed for the color wheel substrate. As exemplified in  FIG. 3 , the non-circular substrate  511  is formed into a rectangle. At least one piece of segment  512  composing the color wheel  5  can be cut out from the non-circular substrate  511 . The segment  512  shown in  FIG. 3  is formed into a semi-circle) (180°) whereby the complete color wheel  5  is formable by two pieces of the segments  512 . However, as necessary, the segment  512  may be further divided. As the first die  22 , a die having a cavity  22   b  in which the non-circular substrate  511  is positioned is used. Further, as the second die  24 , a die having a cavity  24   b  is used. Here, the cavity  24   b  of the die forms a space patterning a desired phosphor layer configuration for at least one segment  512  on the surface of the non-circular substrate  511  positioned in the cavity  22   b  of the first die  22 . The first die  22  and the second die  24  are clamped. After the phosphor additive resin  504  is thermoset on the surface of the non-circular substrate  511 , the segment  512  having a desired form is cut out. By combining the plurality of segments  512 , the color wheel  5  in a segment type can be thus formed as shown in  FIG. 3C . Here, after the phosphor additive resin  504  is circularly applied on the non-circular substrate  511  and is thermoset, one piece of the color wheel  5  in a circular shape (that is, a monolithic type) is cut out. 
         [0063]    In the manufacturing method of the color wheel according to the third embodiment of the present invention, a vertical arrangement between the first die  22  and the second die  24 , the configuration of the non-circular substrate  511 , timing in which the phosphor additive resin  504  is injected, etc. are all optionally selectable from the procedures that have been explained in case of the first or the second embodiment. For example, the following manufacturing step may be taken. That is, the color wheel substrate is set to the cavity of the first die for positioning. Then, the phosphor additive resin  504  is injected into the cavity of the second die. Next, the first die and the second die are clamped. Lastly, the phosphor additive resin  504  is sealed in a space patterning a desired phosphor layer configuration, the space being formed by the surface of the color wheel substrate and the cavity of second die. Further, by changing the color of the phosphor additive resin  504  (or the phosphor layer) for each of the segments  512 , it would be possible to obtain the color wheel  5  that has specific different colored segments in a particular proportion, or that has different kinds of the segments. Here, it can further provide another advantage of clearly defining the border of each phosphor layer in different colors. The detail explanation of operational effects identical with the first and the second embodiments will be omitted. 
         [0064]    Next, with reference to  FIG. 4 , the fourth embodiment of the present invention will be described hereinbelow. Here, portions identical with the prior art and the first to the fourth embodiments will be indicated with the same referential number, and the detail explanation thereof is omitted. 
         [0065]    In the fourth embodiment of the present invention, as the phosphor layer contour correcting device  20 , instead of the second die  24  that has been applied in the first to the third embodiments, a transparent substrate  26  that has a concave portion  26   a  identical with the cavity  24   a  ( 24   b ) of the second die  24  is applied. Further, instead of the first die  22 , a flat holder  28  is applied. On the flat holder  28 , the color wheel substrate  501  ( 511 ) is placed. In a condition where the flat holder  28  is combined with the transparent substrate  26 , the concavity  26   a  of the transparent substrate  26  is adapted to open in the side end face direction of the color wheel substrate  501  ( 511 ). 
         [0066]    The phosphor additive resin  504  is sealed in a space A patterning a desired phosphor layer configuration that is formed between the surface of the color wheel substrate  501  ( 511 ) and the concavity  26   a  of the transparent substrate  26 . Here, in case that the viscosity of the phosphor additive resin  504  is low, the side end face of the concavity of the transparent substrate may be sealed as necessary with a detachable circular cover, etc. when the phosphor additive resin  504  is injected. This can prevent the phosphor additive resin  504  from excessively traveling toward the side end face of the color wheel substrate  501  ( 511 ). Then, the phosphor additive resin  504  on the surface of the color wheel substrate  501  ( 511 ) is thermoset so as to obtain the color wheel  5  where the transparent substrate  26  is left as a component of the finished color wheel. 
         [0067]    Moreover, in the fourth embodiment of the present invention, by using a mold release agent and the like, the transparent substrate  26  may be removed without being left as a component of the finished color wheel. In this case, the transparent substrate  26  may be any non-transparent material. Further, without using the flat holder  28 , the first die  22  as shown in  FIGS. 1 to 3  may be used in combination with the transparent substrate  26 . Here, since it is preferable that the component of the transparent substrate  26  has a superior optical feature and high heat resistance, glass or polycarbonate, etc. is suitable. On the other hand, non-transparent substrates will be satisfied as long as they have high heat resistance. Accordingly, glass, polyamideimide resin (PAI resin), PBT resin, fluororesin, phenol resin, epoxy resin, etc. may be said as suitable (since they have heat resistance). The flat holder may be any material as long as it has necessary heat resistance. Detail explanation of other operational effects identical with the first to the third embodiments of the present invention will be omitted here. 
         [0068]    Next, with reference to  FIG. 5 , the fifth embodiment of the present invention will be explained hereinafter. Here, portions identical with the prior art and the first to the fourth embodiments of the present invention will be indicated with the same referential number, and the detail explanation thereof will be omitted here. 
         [0069]    In the fifth embodiment of the present invention, as shown in  FIG. 5A , the cavity of the second die  24  has a surface on which a convexoconcave configuration  24   c  is formed. This convexoconcave configuration  24   c  has a shape that forms an antireflection structure  30  each shown from  FIG. 5D  to  FIG. 5F . The convexoconcave configuration  24   c  transfers a predetermined convexoconcave forms on the surface of the phosphor additive rein  504  so as to constitute the surface of the phosphor additive resin  504  by itself to have an antireflection structure. Here,  FIG. 5D  to  FIG. 5F  exemplify the configuration of the antireflection structure  30 . The antireflection structure  30 A where the wall of its square pyramid is structured by a curved surface while the upper end portion of the square pyramid is made flat has the lowest reflective ratio and has a wide conical aperture. The antireflective ratio will be lowered in order of an antireflection structure  30 B with a simple square pyramid and an antireflection structure  30 C with a dome configuration. 
         [0070]    In general, it is difficult to apply an anti-reflection treatment coating (AR coating) on a prethermosetting soft resin. In the fifth embodiment of the present invention, however, since the surface of the phosphor additive resin  504  by itself has the antireflection structure  30 , it makes possible to improve the application efficiency of light. Detail explanation of other operational effects identical with the first to the fourth embodiments of the present invention will be omitted here. 
         [0071]    As discussed hereinabove, according to the first to the fifth embodiments of the present invention, irrespective of the viscosity of the phosphor additive resin  504 , it would be possible to manufacture the color wheel  5  for a projector where a phosphor layer, the thickness of which is constant in the radius direction of the color wheel  5 , is formed at a predetermined area of the color wheel  5  in its circumferential direction. Accordingly, irregular color generated on the color wheel  5  for a projector becomes preventable. Further, since occurrence of the irregular color in a projector where the color wheel  5  for a projector is included in its projection optical system can be prevented, chromaticity of images projected by the projector is improved. 
         [0072]    Hereinbelow, with reference to  FIGS. 6 and 7 , effects of the embodiments of the present invention will be explained. 
         [0073]    According to the embodiments of the present invention, not only is it possible to provide the color wheel  5  for a projector where the phosphor additive resin  504  has superior surface smoothness, but it is also able to make the layer of the phosphor additive resin  504  to be as thin as possible (for example, 0.6 mm or less) by using the phosphor layer contour correcting device  20  such as the first die  22 , the second die  24 , etc. Further, even if the viscosity of the phosphor additive resin  504  is low, it is still possible to obtain the same effects discussed hereinabove. 
         [0074]    In addition, by making the thickness of the layer of the phosphor additive resin  504  to be as thin as possible, the following effect becomes attainable. First, in case that the layer of the phosphor additive resin  504  is constant, and, for example, a blue light B output form the blue illuminant  1  (see  FIG. 8 ) passes through the lens  4  and is irradiated in focus on the color wheel substrate  5 , as shown in  FIG. 6 , light reflected from the color wheel substrate  501  can go back to the lens  4  even though a so-called Lambert Distribution (LD) is indicated. 
         [0075]    Here, however, if the blue light B is not correctly focused on the color wheel  501 , as shown in  FIG. 6B , a partial reflective light in the Lambert Distribution LD′ fails to go back to the lens  4 . Also, in case that a focus distance is not matched, peak intensity will be deteriorated as shown in  FIGS. 6C and 6D . 
         [0076]    Furthermore, as shown in  FIGS. 6E and 6F , in case that the surface of the layer of the phosphor additive resin  504  is inclined, and the relative inclined angle of the surface of the phosphor additive resin  504  relative to the optical axis  4 C of the lens  4  becomes large, as shown in  FIGS. 7A to 7C , a so-called coma aberration F is generated so as to deform a light spot. Since the coma aberration F can be determined by the following Formula ( 1 ), it can be said that making the thickness t of a disc to be thin will become advantageous to reduce the occurrence of the coma aberration F. 
         [0000]        W={x ·( n   2 −1)· n   2 ·NA 3 ·cos(tilt)·sin (tilt)· t }/{( n   2 −sin 2 (tilt)) 5/2 ·λ}  FORMULA (1)
 
         [0077]    Here, n is a refractive index; NA is a numerical aperture; t is the thickness of a disc; λ is a laser wavelength; λ is a coefficient; tilt is (R 2 +T 2 ) 1/2 ; R is a radial skew; and T is a tangential skew. 
         [0078]    According to the above relation, as shown in  FIGS. 7D to 7F , the thinner the thickness of the layer of the phosphor additive resin  504  becomes, the larger the tolerant level of an optical intensity becomes relative to the relative inclined angle of the surface of the phosphor additive resin  504  to the optical axis  4 C of the lens  4 . Thus, according to the embodiments of the present invention, by making the layer of the phosphor additive resin  504  to be as thin as possible, it becomes possible to enlarge the optical intensity that is reflected by the color wheel  5  for a projector.