Abstract:
A projector includes: a spatial light modulator provided for each color light flux and configured to modulate the light flux in accordance with an image signal; a light combining system configured to combine the color light flux outputted from the spatial light modulator; a projection system configured to project the light combined by the light combining system; a fixing member configured to integrally fix the spatial light modulator, the light combining system, and the projection system; a base on which the spatial light modulators and the light combining system fixed to the fixing member are mounted; and a cover member configured to cover the spatial light modulator and the light combining system mounted on the base, wherein the base and the cover member form a cooling duct through which cooling air for sequentially cooling the spatial light modulator for the respective color light flux flows.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a projector and a method for manufacturing the same, and particularly to a projector including a liquid crystal display panel. 
         [0003]    2. Related Art 
         [0004]    Developments of projectors have been intended to improve projection performance and reduce their sizes. Projectors including, for example, transmissive liquid crystal display panels for red (R) light, green (G) light, and blue (B) light are widely used. The liquid crystal display panels absorb illumination light and generate heat. To dissipate the heat generated in the liquid crystal display panels, for example, a fan that allows cooling air to flow is used. 
         [0005]    In a known structure for cooling a projector, cooling air flows in a direction substantially perpendicular to a plane containing optical axes in which liquid crystal display panels are disposed. In this case, the cooling air is readily supplied uniformly to the liquid crystal display panels, whereas fans and ducts that allow the cooling air to flow disposed above and below the respective liquid crystal display panels disadvantageously make it difficult to reduce the thickness of the projector. In a technology having been proposed to solve the problem, a flow path along which the cooling air flows in a direction substantially parallel to the plane containing the optical axes is provided, and the cooling air sequentially cools the liquid crystal display panels and associated polarizers. For example, JP-A-2001-281613 proposes a configuration in which liquid crystal display panels are disposed around a cross dichroic prism, which is a light combining system, and flow paths are provided on the light-incident side and the light-exiting side of the liquid crystal display panels. 
         [0006]    Liquid crystal display panels, a cross dichroic prism, and a projection lens, which are optical components, are positioned with respect to each other and then fixed to ensure optical characteristics necessary for a projector. When the technology described in JP-A-2001-281613 is employed, it is a challenge to assemble a configuration for fixing the optical components in the projector and a configuration for cooling the optical components. 
       SUMMARY 
       [0007]    An advantage of some aspects of the invention is to provide not only a projector including a cooling structure that allows the thickness of the projector to be reduced and a configuration that allows optical components to be fixed but also a method for manufacturing the projector. 
         [0008]    A projector according to an aspect of the invention includes a spatial light modulator provided for each color light flux and configured to modulate the light flux in accordance with an image signal, a light combining system configured to combine the color light fluxes outputted from the spatial light modulators, a projection system configured to project the light combined by the light combining system, a fixing member configured to integrally fix the spatial light modulator, the light combining system, and the projection system, a base on which the spatial light modulator and the light combining system fixed to the fixing member are mounted, and a cover member configured to cover the spatial light modulator and the light combining system mounted on the base. The base and the cover member form a cooling duct through which cooling air for sequentially cooling the spatial light modulator for the respective color light flux flows. 
         [0009]    The spatial light modulator, the light combining system, and the projection system are positioned with respect to each other and fixed to the fixing member. The cooling duct formed of the base and the cover member causes the cooling air to flow around the light combining system and sequentially travel through the vicinities of the spatial light modulator. The resultant projector includes a cooling structure that allows the thickness of the projector to be reduced and a configuration that allows optical components to be fixed. 
         [0010]    A projector according to another aspect of the invention includes a spatial light modulator provided for each color light flux and configured to modulate the light flux in accordance with an image signal, a light combining system configured to combine the color light fluxes outputted from the spatial light modulators, a projection system configured to project the light combined by the light combining system, a fixing member configured to integrally fixes the spatial light modulator and the light combining system, a base on which the spatial light modulator and the light combining system fixed to the fixing member are mounted and to which the projection system is fixed, and a cover member configured to cover the spatial light modulator and the light combining system mounted on the base. The base and the cover member form a cooling duct through which cooling air for sequentially cooling the spatial light modulator for the respective color light flux flows. 
         [0011]    The spatial light modulator and the light combining system are positioned with respect to each other and fixed to the fixing member. The spatial light modulator and the light combining system fixed to the fixing member and the projection system are positioned with respect to each other and fixed to the base. The cooling duct formed of the base and the cover member causes the cooling air to flow around the light combining system and sequentially travel through the vicinities of the spatial light modulator. The resultant projector includes a cooling structure that allows the thickness of the projector to be reduced and a configuration that allows optical components to be fixed. 
         [0012]    In a preferred embodiment of the invention, it is preferable that the projector further includes a support frame configured to support the spatial light modulator and the fixing member has a support frame fixing portion configured to fix each of the support frame. The spatial light modulator can thus be fixed to the fixing member via the support frame. 
         [0013]    In a preferred embodiment of the invention, it is preferable that the support frame has an attachment portion configured to allow the support frame fixing portion to be attached to the support frame, and the spatial light modulator is fixed after the position thereof relative to the light combining system is adjusted in response to the gap between the attachment portion and the support frame fixing portion. In this way, the light combining system and the spatial light modulator can be fixed in a simple configuration in such a way that they are precisely positioned with respect to each other. 
         [0014]    In a preferred embodiment of the invention, it is preferable that the projector further includes a light-exiting-side polarizer provided for the respective color light flux and on which the light flux outputted from the spatial light modulator is incident, and that the light-exiting-side polarizer is attached to the fixing member. The light-exiting-side polarizer can thus be fixed in the optical paths between the spatial light modulator and the light combining system. 
         [0015]    In a preferred embodiment of the invention, it is preferable that the projector further includes a light-incident-side polarizer provided for the respective color light flux and on which light flux traveling toward the spatial light modulator is incident, and the light-incident-side polarizer is disposed in sidewall portions that form the sidewall of the cooling duct and face the spatial light modulator. In this way, the light-exiting surface of the light-incident-side polarizer form part of the cooling duct, and the cooling air can cool the light-incident-side polarizer. 
         [0016]    In a preferred embodiment of the invention, it is preferable that the projector further includes a light-incident-side polarizer frame configured to allow the light-incident-side polarizer to be attached to the corresponding sidewall portion, and the light-incident-side polarizer frame is fixed to the sidewall portion after the inclination of the corresponding light-incident-side polarizer is adjusted in the rotational direction around an optical axis. In this way, the orientation of the axis of polarization of the light-incident-side polarizer can be finely adjusted in a simple configuration, whereby the light-incident-side polarizer can be fixed with the inclination thereof precisely adjusted. 
         [0017]    In a preferred embodiment of the invention, it is preferable that the projector further includes a rectifying mechanism provided between the spatial light modulator and causing the cooling air to flow through the light-incident side and the light-exiting side of the spatial light modulator. The rectifying mechanism cause the cooling air to travel toward both the light-incident side and the light-exiting side of the spatial light modulators and can hence efficiently cool the light-incident-side polarizer, the spatial light modulator, and the light-exiting-side polarizer. 
         [0018]    In a preferred embodiment of the invention, it is preferable that the rectifying mechanism is attached to either the base or the cover member. As a result, the cooling duct including the rectifying mechanism is formed by combining the base and the cover member. 
         [0019]    In a preferred embodiment of the invention, it is preferable that the projector further includes a cooling air supplier configured to supply the cooling air. The cooling air supplier causes the cooling air to flow through the cooling duct. 
         [0020]    A method for manufacturing a projector according to still another aspect of the invention is a method for manufacturing a projector including a spatial light modulator provided for each color light flux and configured to modulate the light flux in accordance with an image signal, a light combining system configured to combine the color light flux outputted from the spatial light modulator, and a projection system configured to project the light combined by the light combining system. The method includes integrally fixing the spatial light modulators, the light combining system, and the projection system using a fixing member, mounting the spatial light modulator and the light combining system fixed to the fixing member on a base, and covering the spatial light modulator and the light combining system mounted on the base with a cover member. The base and the cover member form a cooling duct through which cooling air for sequentially cooling the spatial light modulator for the respective color light flux flows. The resultant projector includes a cooling structure that allows the thickness of the projector to be reduced and a configuration that allows optical components to be fixed. 
         [0021]    A method for manufacturing a projector according to yet another aspect of the invention is a method for manufacturing a projector including a spatial light modulator provided for each color light flux and configured to modulate the light flux in accordance with an image signal, a light combining system configured to combine the color light flux outputted from the spatial light modulator, and a projection system configured to project the light combined by the light combining system. The method includes fixing the projection system to a base, mounting the light combining system fixed to a fixing member on the base, integrally fixing the spatial light modulator and the light combining system to the fixing member by attaching the spatial light modulator to the fixing member, and covering the spatial light modulator and the light combining system mounted on the base with a cover member. The base and the cover member form a cooling duct through which cooling air for sequentially cooling the spatial light modulator for the respective color light flux flows. The resultant projector includes a cooling structure that allows the thickness of the projector to be reduced and a configuration that allows optical components to be fixed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The invention will be described with reference to the accompanying drawings, wherein like numbers refer to like elements. 
           [0023]      FIG. 1  shows a schematic configuration of a projector according to a first embodiment. 
           [0024]      FIG. 2  is a perspective view showing the configuration of a combination of a cooling structure and a projection lens. 
           [0025]      FIG. 3  is an exploded view of the configuration shown in  FIG. 2 . 
           [0026]      FIG. 4  shows part of the configuration shown in  FIG. 2 . 
           [0027]      FIG. 5  is a horizontal cross-sectional view of the configuration shown in  FIG. 2  taken along the line A-A. 
           [0028]      FIG. 6  is a vertical cross-sectional view of the configuration shown in  FIG. 2  taken along the line B-B. 
           [0029]      FIG. 7  is an exploded view showing a cooling structure and other components in a projector according to a second embodiment. 
           [0030]      FIG. 8  is a perspective view of a cover member viewed from the rear side of the cover member shown in  FIG. 7 . 
           [0031]      FIG. 9  shows part of the configuration shown in  FIG. 7 . 
           [0032]      FIG. 10  is a horizontal cross-sectional view showing the configuration of a combination of a cooling structure and a projection lens. 
           [0033]      FIG. 11  describes how to attach liquid crystal display panels. 
           [0034]      FIG. 12  is a perspective view of a cooling structure according to a variation of the second embodiment. 
           [0035]      FIG. 13  is a perspective view of a cover member from which light-incident-side polarizer frames are removed. 
           [0036]      FIG. 14  is a perspective view of one of the light-incident-side polarizer frames viewed from the side facing the interior of a cooling duct. 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0037]    Embodiments of the invention will be described below in detail with reference to the drawings. 
       First Embodiment 
       [0038]      FIG. 1  shows a schematic configuration of a projector  10  according to a first embodiment. The projector  10  is a front-projection projector, which projects projection light onto a screen  32  and presents an image to a viewer who observes the light reflected off the screen  32 . The projector  10  includes a cooling duct through which cooling air supplied from a fan  31  flows. The cooling duct will be described later in detail. 
         [0039]    A light source  11  emits light containing R light, G light, and B light. The light source  11  is, for example, an ultra-high pressure mercury lamp. Each of a first integrator lens  12  and a second integrator lens  13  includes a plurality of lens elements arranged in an array. The first integrator lens  12  divides the light flux from the light source  11  into a plurality of sub-fluxes. Each of the lens elements in the first integrator lens  12  focuses the light flux from the light source  11  in the vicinity of the corresponding lens element in the second integrator lens  13 . The lens elements in the second integrator lens  13  form images of the lens elements in the first integrator lens  12  on liquid crystal display panels  23 R,  23 G, and  23 B. 
         [0040]    A polarization conversion element  14  converts the light having passed through the two integrator lenses  12  and into predetermined linearly polarized light. A superimposing lens  15  superimposes the images of the lens elements in the first integrator lens  12  on illuminated surfaces of the liquid crystal display panels  23 R,  23 G, and  23 B. The first integrator lens  12 , the second integrator lens  13 , and the superimposing lens  15  make the intensity distribution of the light from the light source  11  uniform on the illuminated areas of the liquid crystal display panels  23 R,  23 G, and  23 B. 
         [0041]    A first dichroic mirror  16  reflects the R light and transmits the G light and the B light incident thereon from the superimposing lens  15 . The optical path of the R light from the superimposing lens  15  is deflected by the first dichroic mirror  16  and a reflection mirror  18 , and the reflected light is incident on a field lens  21 R. The field lens  21 R parallelizes the R light from the reflection mirror  18 , and the parallelized light is incident on a light-incident-side polarizer  22 R. The light-incident-side polarizer  22 R transmits predetermined linearly polarized light. The liquid crystal display panel  23 R, which is a spatial light modulator, modulates the R light from the light-incident-side polarizer  22 R in accordance with an image signal. A light-exiting-side polarizer  24 R transmits predetermined linearly polarized light out of the light from the liquid crystal display panel  23 R. The light-incident-side polarizer  22 R and the light-exiting-side polarizer  24 R are disposed in such a way that the axes of polarization thereof are perpendicular to each other. 
         [0042]    A second dichroic mirror  17  reflects the G light and transmits the B light from the first dichroic mirror  16 . The optical path of the G light from the first dichroic mirror  16  is deflected by the second dichroic mirror  17 , and the reflected light is incident on a field lens  21 G. The field lens  21 G parallelizes the G light from the second dichroic mirror  17 , and the parallelized light is incident on a light-incident-side polarizer  22 G. The light-incident-side polarizer  22 G transmits predetermined linearly polarized light. The liquid crystal display panel  23 G, which is a spatial light modulator, modulates the G light from the light-incident-side polarizer  22 G in accordance with an image signal. A light-exiting-side polarizer  24 G transmits predetermined linearly polarized light out of the light from the liquid crystal display panel  23 G. 
         [0043]    The B light having passed through the second dichroic mirror  17  passes through a relay lens  26  and is reflected off a reflection mirror  19 , where the optical path of the B light is deflected. The B light from the reflection mirror  19  passes through another relay lens  27 , is reflected off a reflection mirror  20 , where the optical path of the B light is deflected, and is incident on a field lens  21 B. In the present embodiment, the length of the optical path for the B light is longer than those for the R light and the G light. To make the magnification of the illumination light B on the illuminated area of the liquid crystal display panel  23 B equal to those of the other illumination light on the illuminated areas of the liquid crystal display panel  23 R and  23 G, the optical path for the B light includes a relay system formed of the relay lenses  26  and  27 . 
         [0044]    The field lens  21 B parallelizes the B light from the reflection mirror  20 , and the parallelized light is incident on a light-incident-side polarizer  22 B. The light-incident-side polarizer  22 B transmits predetermined linearly polarized light. The liquid crystal display panel  23 B, which is a spatial light modulator, modulates the B light from the light-incident-side polarizer  22 B in accordance with an image signal. A light-exiting-side polarizer  24 B transmits predetermined linearly polarized light out of the light from the liquid crystal display panel  23 B. The light-incident-side polarizers  22 R,  22 G, and  22 B, the liquid crystal display panels  23 R,  23 G, and  23 B, and the light-exiting-side polarizers  24 R,  24 G, and  24 B correspond to the respective colors. 
         [0045]    A cross dichroic prism  25 , which is a light combining system, combines the R light, the G light, and the B light having exited from the light-exiting-side polarizers  24 R,  24 G, and  24 B and outputs the combined light toward a projection lens  30 . The projection lens  30 , which is a projection system, projects the light combined in the cross dichroic prism  25  toward the screen  32 . A fan  31 , which is a cooling air supplier, supplies cooling air flowing through the cooling duct. The fan  31  may be a sirocco fan or any other fan capable of supplying cooling air. 
         [0046]      FIG. 2  is a perspective view showing the configuration of a combination of a cooling structure and the projection lens  30  in the projector  10 .  FIG. 3  is an exploded view of the configuration shown in  FIG. 2 . The cooling structure includes the light-incident-side polarizers  22 R,  22 G, and  22 B, the liquid crystal display panels  23 R,  23 G, and  23 B, the light-exiting-side polarizers  24 R,  24 G, and  24 B, and the cross dichroic prism  25 , which are optical components, integrated with the cooling duct. 
         [0047]    A base  40  and a cover member  41  form an outer shell of the cooling duct. The base  40  includes a sidewall portion  42  and a bottom portion  43 . The sidewall portion  42  forms the sidewall of the cooling duct. The bottom portion  43  is a flat-plate portion that forms the bottom surface of the cooling duct. The liquid crystal display panels  23 R,  23 G, and  23 B, the light-exiting-side polarizers  24 R,  24 G, and  24 B, and the cross dichroic prism  25  fixed to a fixing member  47  are mounted on the bottom portion  43 . The cover member  41  is a flat-plate member that forms the top surface of the cooling duct that is opposite the bottom portion  43 . The cover member  41  covers the liquid crystal display panels  23 R,  23 G, and  23 B, the light-exiting-side polarizers  24 R,  24 G, and  24 B, and the cross dichroic prism  25  mounted on the base  40 . 
         [0048]      FIG. 4  shows part of the configuration shown in  FIG. 2 .  FIG. 4  shows not only the configuration surrounded by the base  40  and the cover member  41  but also the projection lens  30 . The liquid crystal display panels  23 R,  23 G, and  23 B are supported by respective support frames  46 . The fixing member  47  integrally fixes the liquid crystal display panels  23 R,  23 G, and  23 B, the cross dichroic prism  25 , and the projection lens  30 . The fixing member  47  includes a plurality of flat-plate portions. 
         [0049]    The cross dichroic prism  25  is sandwiched between two flat-plate portions of the fixing member  47 , upper and lower flat-plate portions. The support frame  46  provided for each of the liquid crystal display panels  23 R,  23 G, and  23 B is fixed to support frame fixing portions  50  of the fixing member  47 . The support frame fixing portions  50  are elongated extensions of the fixing member  47  that extend from the portion where the cross dichroic prism  25  is fixed toward the liquid crystal display panels  23 R,  23 G, and  23 B. The liquid crystal display panels  23 R,  23 G, and  23 B are fixed to the support frame fixing portions  50  via the support frames  46 . 
         [0050]    Each of the support frames  46  has four recesses  51  into which the corresponding support frame fixing portions  50  fit. The recesses  51  function as attachment portions that allow the support frame fixing portions  50  to be attached to the support frame  46 . The support frame  46  is fixed by two support frame fixing portions  50  extending above the cross dichroic prism  25  and two support frame fixing portions  50  extending below the cross dichroic prism  25 . The projection lens  30  is fixed to a projection system fixing portion  52 . The projection system fixing portion  52  is formed of right and left flat-plate portions of the fixing member  47  that sandwich the vicinity of the light-exiting surface of the cross dichroic prism  25 . 
         [0051]    The light-exiting-side polarizers  24 R,  24 G, and  24 B are attached to the support frame fixing portions  50  and located between the liquid crystal display panels  23 R,  23 G,  23 B and the light-incident surfaces of the cross dichroic prism  25 . As a result, the light-exiting-side polarizers  24 R,  24 G, and  24 B are fixed in the optical paths between the liquid crystal display panels  23 R,  23 G,  23 B and the cross dichroic prism  25 . The light-exiting-side polarizers  24 R,  24 G, and  24 B are not necessarily attached to the support frame fixing portions  50  but may be attached to any portions of the fixing member  47 . 
         [0052]    Referring back to  FIG. 3 , openings  45  through which light passes are formed in the portions of the sidewall portion  42  that face the liquid crystal display panels  23 R,  23 G, and  23 B. The light-incident-side polarizers  22 R,  22 G, and  22 B are disposed in the openings  45  so that the polarizers block the openings. The light-exiting surfaces of the light-incident-side polarizers  22 R,  22 G, and  22 B thus form part of the cooling duct. Two rectifying mechanisms  44  are disposed, one between the liquid crystal display panel  23 B for B light and the liquid crystal display panel  23 G for G light and the other between the liquid crystal display panel  23 G for G light and the liquid crystal display panel  23 R for R light. The rectifying mechanisms  44  are attached to the bottom portion  43 . 
         [0053]      FIG. 5  is a horizontal cross-sectional view of the configuration shown in  FIG. 2  taken along the line A-A. The cooling duct is bent at two locations, one between the components for B light and those for G light and the other between the components for G light and those for R light. The inner circumferential surface of the cooling duct is formed of the light-incident surfaces of the cross dichroic prism  25 . The rectifying mechanisms  44  are disposed at the respective bent portions of the cooling duct. The two rectifying mechanisms  44  divide the cooling duct into a flow path on the light-incident side of the liquid crystal display panels  23 R,  23 G, and  23 B and a flow path on the light-exiting side thereof. 
         [0054]      FIG. 6  is a vertical cross-sectional view of the configuration shown in  FIG. 2  taken along the line B-B. The cover member  41  is in close contact with and attached to a plate-shaped portion of the fixing member  47  that is located above the cross dichroic prism  25 . The bottom portion  43  of the base  40  is in close contact with and attached to a plate-shaped portion of the fixing member  47  that is located below the cross dichroic prism  25 . The base  40  and the cover member  41  are thus fixed to the cross dichroic prism  25 . A member that relaxes tolerance, such as an elastic member made of rubber or any other suitable material, may be disposed between the cover member  41  and the fixing member  47 . In this case, the cover member  41  may be fixed to the base  40 . 
         [0055]    A description will be made of how cooling air travels in the cooling duct with reference to  FIGS. 5 and 6 . An inlet  53  and an outlet  54  of the cooling duct are formed of the sidewall portion  42 , the bottom portion  43 , the cover member  41 , and the projection system fixing portion  52 . The inlet  53  is an opening located on the side where the optical components for B light are present in the cooling duct. The outlet  54  is an opening located on the side where the optical components for R light are present in the cooling duct. The fan  31  supplies cooling air to the inlet  53  of the cooling duct. The traveling direction of the cooling air having passed between the light-incident surface of the liquid crystal display panel  23 B for B light and the light-exiting surface of the light-incident-side polarizer  22 B is deflected between the sidewall portion  42  and the outer circumferential surface of the rectifying mechanism  44  located downstream of the components for B light. 
         [0056]    The cooling air having passed between the sidewall portion  42  and the rectifying mechanism  44  passes between the light-incident surface of the liquid crystal display panel  23 G for G light and the light-exiting surface of the light-incident-side polarizer  22 G, and the traveling direction of the cooling air is deflected between the sidewall portion  42  and the outer circumferential surface of the rectifying mechanism  44  located downstream of the components for G light. The cooling air having passed between the sidewall portion  42  and the rectifying mechanism  44  passes between the light-incident surface of the liquid crystal display panel  23 R for R light and the light-exiting surface of the light-incident-side polarizer  22 R. 
         [0057]    The traveling direction of the cooling air having passed between the light-exiting surface of the liquid crystal display panel  23 B for B light and the corresponding light-incident surface of the cross dichroic prism  25  is deflected between the inner circumferential surface of the rectifying mechanism  44  located downstream of the components for B light and the cross dichroic prism  25 . The cooling air having passed between the rectifying mechanism  44  and the cross dichroic prism  25  passes between the light-exiting surface of the liquid crystal display panel  23 G for G light and the corresponding light-incident surface of the cross dichroic prism  25 , and the traveling direction of the cooling air is deflected between the inner circumferential surface of the rectifying mechanism  44  located downstream of the components for G light and the cross dichroic prism  25 . 
         [0058]    The cooling air having passed between the rectifying mechanism  44  and the cross dichroic prism  25  passes between the light-exiting surface of the liquid crystal display panel  23 R for R light and the corresponding light-incident surface of the cross dichroic prism  25 . The cooling air having passed through the light-incident side of the liquid crystal display panel  23 R for R light and the cooling air having passed through the light-exiting side thereof flow out of the cooling duct through the outlet  54 . 
         [0059]    In the cross-sectional view of  FIG. 6 , the cooling air travels between the light-exiting surface of the light-incident-side polarizer  22 G for G light and the light-incident surface of the liquid crystal display panel  23 G for G light, between the light-exiting surface of the liquid crystal display panel  23 G and the light-incident surface of the light-exiting-side polarizer  24 G, and between the light-exiting surface of the light-exiting-side polarizer  24 G and the cross dichroic prism  25 . The cooling air travels through the optical components for B light and the optical components for R light in the same manner as through the optical components for G light. 
         [0060]    The cooling air flowing through the cooling duct removes the heat generated in the light-incident-side polarizers  22 R,  22 G, and  22 B, the liquid crystal display panels  23 R,  23 G, and  23 B, and the light-exiting-side polarizers  24 R,  24 G, and  24 B out of the projector  10 . The rectifying mechanisms  44  provided in the cooling duct cause the cooling air to travel toward both the light-incident side and the light-exiting side of the liquid crystal display panels  23 R,  23 G, and  23 B and can hence efficiently cool the light-incident-side polarizers  22 R,  22 G, and  22 B, the liquid crystal display panels  23 R,  23 G, and  23 B, and the light-exiting-side polarizers  24 R,  24 G, and  24 B. 
         [0061]    The procedure of assembling the configuration shown in  FIG. 2  will next be described with reference to  FIGS. 3 and 4 . The configuration shown in  FIG. 4  has been assembled before the base  40  and the cover member  41  shown in  FIG. 3  are attached. The liquid crystal display panels  23 R,  23 G, and  23 B, the light-exiting-side polarizers  24 R,  24 G, and  24 B, the cross dichroic prism  25 , and the projection lens  30  are integrally fixed to the fixing member  47 . The liquid crystal display panels  23 R,  23 G, and  23 B and the projection lens  30  are fixed with the positions thereof relative to the cross dichroic prism  25  adjusted via the fixing member  47 . 
         [0062]    The liquid crystal display panels  23 R,  23 G, and  23 B are fixed to the fixing member  47  via the support frames  46 . The recesses  51  are formed in such away that the width thereof is slightly larger than that of the support frame fixing portions  50 . The positions of the liquid crystal display panels  23 R,  23 G, and  23 B are finely adjusted by changing the positions of the recesses  51  relative to the support frame fixing portions  50 . After the positions of the liquid crystal display panels  23 R,  23 G, and  23 B are adjusted, an adhesive member (not shown) filled in the gap between each of the recesses  51  and the corresponding support frame fixing portion  50  is solidified. The liquid crystal display panels  23 R,  23 G, and  23 B are thus fixed after the positions thereof relative to the cross dichroic prism  25  are adjusted by using the gaps between the recesses  51  and the support frame fixing portions  50 . 
         [0063]    In this way, the cross dichroic prism  25  and the liquid crystal display panels  23 R,  23 G, and  23 B can be fixed in a simple configuration in such away that they are precisely positioned with respect to each other. The shapes of the support frame fixing portions  50  and the recesses  51  are not limited to those illustrated but can be changed as appropriate. The attachment portion formed in each of the support frames  46  may not be the recess  51  but may be any other configuration to which the corresponding support frame fixing portion  50  can be attached. The attachment portion may, for example, be a through hole into which the support frame fixing portion  50  can be inserted. The number of attachment portions and support frame fixing portions  50  and the positions thereof are not limited to those described in the present embodiment but may be changed as appropriate. 
         [0064]    The liquid crystal display panels  23 R,  23 G, and  23 B and the cross dichroic prism  25  integrally fixed to the fixing member  47  are mounted on the bottom portion  43  of the base  40  via the fixing member  47 . The components mounted on the base  40  are then covered with the cover member  41  by attaching the cover member  41 . The cover member  41  is in close contact with and attached to the plate-shaped portion of the fixing member  47  that is located above the cross dichroic prism  25 . The cooling duct including the rectifying mechanisms  44  is formed by combining the base  40 , to which the rectifying mechanisms  44  have been attached in advance, with the cover member  41 . The fan  31  is further attached to the inlet  53 . The rectifying mechanisms  44  are not necessarily attached to the base  40  but may instead be attached to the cover member  41 . 
         [0065]    The thickness of the projector  10  can be reduced by employing the configuration in which the cooling air sequentially travels toward the liquid crystal display panels  23 R,  23 G, and  23 B and other components and arranging the fan  31 , the cooling duct, and the optical components, which are objects to be cooled, in the horizontal direction. Further, the configuration described in the present embodiment allows the configuration for fixing the optical components and the configuration for cooling the optical components to be assembled. The assembled projector  10  thus advantageously includes the cooling structure that allows the thickness of the projector  10  to be reduced and the configuration that allows the optical components to be fixed. 
         [0066]    The cooling air does not necessarily travel through the optical components for the RGB colors in the order described in the present embodiment. The order in which the cooling air travels may be changed as appropriate in accordance with the arrangement of the optical components for the RGB colors. The cooling duct is not necessarily configured in such a way that the inlet  53  is the opening on the side where the optical components for B light are present and the outlet  54  is the opening on the side where the optical components for R light are present. The cooling duct may be configured in such a way that the inlet  53  is the opening on the side where the optical components for R light are present and the outlet  54  is the opening on the side where the optical components for B light are present. The position of the fan  31  may be changed as appropriate in accordance with the position of the inlet  53 . 
       Second Embodiment 
       [0067]      FIG. 7  is an exploded view showing a cooling structure and a projection lens  30  in a projector according to a second embodiment. In the present embodiment, a base  60  onto which the projection lens  30  is fixed and a cover member  61  form a cooling duct. The same portions as those in the first embodiment have the same reference characters, and no redundant description of those portions will be made. 
         [0068]    The base  60  and the cover member  61  form an outer shell of the cooling duct. The base  60  includes a bottom portion  62  and a projection system fixing portion  63 . The bottom portion  62  is a flat-plate portion that forms the bottom surface of the cooling duct. The liquid crystal display panels  23 R,  23 G, and  23 B, the light-exiting-side polarizers  24 R,  24 G, and  24 B, and the cross dichroic prism  25  fixed to a fixing member  66  are mounted on the bottom portion  62 . The projection system fixing portion  63  is formed on the bottom portion  62  of the base  60 . The projection system fixing portion  63 , which is a portion into which the projection lens  30  can be inserted, fixes the projection lens  30  to the base  60 . 
         [0069]    The cover member  61  covers the liquid crystal display panels  23 R,  23 G, and  23 B, the light-exiting-side polarizers  24 R,  24 G, and  24 B, and the cross dichroic prism  25  mounted on the base  60 . The cover member  61  includes a top surface portion  64  and a sidewall portion  65 . The top surface portion  64  is a flat-plate portion that forms the top surface of the cooling duct that is opposite the bottom portion  62 . The sidewall portion  65  forms the sidewall of the cooling duct. 
         [0070]      FIG. 8  is a perspective view of the cover member  61  viewed from the rear side of the cover member  61  shown in  FIG. 7 . Openings  45  through which light passes are formed in the portions of the sidewall portion  65  that face the liquid crystal display panels  23 R,  23 G, and  23 B. The light-incident-side polarizers  22 R,  22 G, and  22 B are disposed in the openings  45  so that the polarizers block the openings. The light-exiting surfaces of the light-incident-side polarizers  22 R,  22 G, and  22 B thus form part of the cooling duct. Rectifying mechanisms  44  are attached to the top surface portion  64 . When the base  60  and the cover member  61  are combined, one of the rectifying mechanisms  44  is disposed between the liquid crystal display panel  23 B for B light and the liquid crystal display panel  23 G for G light, and the other is disposed between the liquid crystal display panel  23 G for G light and the liquid crystal display panel  23 R for R light. 
         [0071]      FIG. 9  shows part of the configuration shown in  FIG. 7 .  FIG. 9  shows the components mounted on the base  60  and the projection lens  30  fixed to the base  60 . The fixing member  66  includes two flat-plate portions. The cross dichroic prism  25  is sandwiched between the two flat-plate portions of the fixing member  66 , upper and lower flat-plate portions. The portion of the projection system fixing portion  63  that faces the cross dichroic prism  25  is connected to the two flat-plate portions of the fixing member  66  and the vicinity of the light-exiting surface of the cross dichroic prism  25 . 
         [0072]      FIG. 10  is a horizontal cross-sectional view showing the configuration of a combination of the cooling structure and the projection lens  30 . An inlet  53  and an outlet  54  of the cooling duct are formed of the sidewall portion  65 , the top surface portion  64 , the bottom portion  62 , and the projection system fixing portion  63 . The inlet  53  is an opening located on the side where the optical components for R light are present in the cooling duct. The outlet  54  is an opening located on the side where the optical components for B light are present in the cooling duct. 
         [0073]    The cooling air supplied through the inlet  53  into the cooling duct sequentially travels through the optical components for R light, the optical components for G light, and the optical components for B light and flows out of the cooling duct through the outlet  54 . In the present embodiment, the cooling air travels in the opposite direction to that in the first embodiment. The cooling duct may alternatively be configured in such a way that the inlet  53  is located on the side where the optical components for B light are present and the outlet  54  is located on the side where the optical components for R light are present with the cooling air traveling in the same direction as that in the first embodiment. 
         [0074]    The procedure of assembling the configuration described in the present embodiment will next be described with reference to  FIGS. 7 to 9  and  11 . The configuration shown in  FIG. 9  has been assembled before the cover member  61  shown in  FIGS. 7 and 8  is attached. The projection lens  30  is fixed to the projection system fixing portion  63 . The cross dichroic prism  25  and the light-exiting-side polarizers  24 R,  24 G, and  24 B are mounted on the bottom portion  62  of the base  60  after they are attached to the fixing member  66 . The projection lens  30  and the cross dichroic prism  25  are fixed with the positions thereof adjusted with respect to each other. 
         [0075]      FIG. 11  describes how to attach the liquid crystal display panels  23 R,  23 G, and  23 B. The liquid crystal display panels  23 R,  23 G, and  23 B are attached to the fixing member  66  after the cross dichroic prism  25  attached to the fixing member  66  is mounted on the base  60 . In the present embodiment, the liquid crystal display panels  23 R,  23 G, and  23 B are advantageously attached after the projection lens  30  and the cross dichroic prism  25  are securely fixed to the base  60  and stabilized thereon. Other advantages are provided in the present embodiment as follows: The sidewall portion  65  does not obstruct the operation of attaching the liquid crystal display panels  23 R,  23 G, and  23 B, and the fact that the rectifying mechanisms  44  do not accidentally come into contact with the liquid crystal display panels  23 R,  23 G, and  23 B at this point prevents the liquid crystal display panels  23 R,  23 G, and  23 B from being shifted. 
         [0076]    The components mounted on the base  60  are then covered with the cover member  61  by attaching the cover member  61 . The cover member  61  is in close contact with and attached to a plate-shaped portion of the fixing member  66  that is located above the cross dichroic prism  25 . The rectifying mechanisms  44  have been attached in advance to the cover member  61 , as shown in  FIG. 8 . The cooling duct including the rectifying mechanisms  44  is formed by combining the base  60  with the cover member  61 . The fan  31  is further attached to the inlet  53 . The rectifying mechanisms  44  are not necessarily attached to the cover member  61  but may instead be attached to the base  60 . In the present embodiment as well, the assembled projector includes the cooling structure that allows the thickness of the projector to be reduced and the configuration that allows the optical components to be fixed. 
         [0077]      FIG. 12  is a perspective view of a cooling structure according to a variation of the present embodiment. Each of the light-incident-side polarizers  22 R,  22 G, and  22 B is attached to the sidewall portion  65  via a light-incident-side polarizer frame  67 . The light-incident-side polarizer frame  67  is fixed to the sidewall portion  65  after the inclination of the corresponding light-incident-side polarizer is adjusted in the rotational direction around the optical axis. The optical axis is an axis perpendicular to the light-incident surfaces of the liquid crystal display panels  23 R,  23 G, and  23 B and passing through the centers of the illuminated areas of the liquid crystal display panels  23 R,  23 G, and  23 B. 
         [0078]      FIG. 13  is a perspective view of the cover member  61  from which the light-incident-side polarizer frames  67  are removed. A cutout  68  is provided in the portion of the sidewall portion  65  to which each of the light-incident-side polarizer frames  67  is attached. The cutout  68  is formed by cutting a lower portion of the sidewall portion  65  in accordance with the shape of the light-incident-side polarizer frame  67 . The portion of the cutout  68  between the side to be joined with the base  60  and the top surface portion  64  has an arcuate shape. 
         [0079]      FIG. 14  is a perspective view of one of the light-incident-side polarizer frames  67  viewed from the side facing the interior of the cooling duct. A rectangular opening  70  is provided at the center of the light-incident-side polarizer frame  67 . The light-incident-side polarizers  22 R,  22 G, and  22 B are disposed in the openings  70  so that the polarizers block the openings. A bent portion  69  is provided on right and left side portions of each of the light-incident-side polarizer frames  67 . Each of the bent portions  69  has a shape that is bent in accordance with the thickness of the member that forms the sidewall portion  65 . 
         [0080]    The light-incident-side polarizer frames  67  are inserted through the lower side of the respective cutouts  68  toward the top surface portion  64  with the light-incident-side polarizers  22 R,  22 G, and  22 B disposed in the openings  70 . The light-incident-side polarizer frames  67  are attached to the sidewall portion  65  when each of the bent portions  69  fits on the edge of the sidewall portion  65  that extends along the cutout  68 . The bent portion  69  can fit on the sidewall portion  65  and slide along the arcuate portion of the cutout  68 . The light-incident-side polarizer frames  67  can be rotated around the optical axis while the bent portions  69  slide along the sidewall portion  65 . The inclination angles of the light-incident-side polarizers  22 R,  22 G, and  22 B are thus finely adjusted in the rotational direction around the optical axis. 
         [0081]    The light-incident-side polarizer frames  67  are fixed to the sidewall portion  65  with an adhesive or any other suitable material after the inclination angles of the light-incident-side polarizers  22 R,  22 G, and  22 B are adjusted. In this way, the orientation of the axis of polarization of each of the light-incident-side polarizers  22 R,  22 G, and  22 B can be finely adjusted in a simple configuration, whereby the light-incident-side polarizers  22 R,  22 G, and  22 B can be fixed with the inclination thereof precisely adjusted. The position, number, and shape of the bent portions  69  are not limited to those described in the present embodiment but may be changed as appropriate. Further, the mechanism that allows the light-incident-side polarizer frames  67  to rotate is not necessarily the bent portions  69 , but any other suitable mechanism may be used. The present variation is applicable to the first embodiment. 
         [0082]    The entire disclosure of Japanese Patent Application No. 2009-185501, filed Aug. 10, 2009 is expressly incorporated by reference herein.