Abstract:
A projector apparatus includes a housing having an air inlet and an air outlet, a light source device provided in the housing, an image projection unit provided in the housing and configured to emit an image projection light beam so as to project an image onto a screen, and a cooling device configured to cool the light source device and the image projecting unit. The cooling device includes a cooling passage extending from the air inlet to the air outlet, and a fan configured to suck in outside air from the air inlet and to exhaust the outside air passing through the cooling passage, out of the housing from the air outlet. The air filter section includes a cylindrical filter body, a filter support member configured to support the filter body, and a rotating unit configured to rotate the filter support member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a projector apparatus. 
         [0003]    2. Description of the Related Art 
         [0004]    Projector apparatuses have been proposed, each of which include a housing, and a light source device and an image projecting unit that are provided in the housing. 
         [0005]    The light source device uses a high-output discharge lamp as a lamp for generating light. 
         [0006]    The image projecting unit produces an image projection light beam from light generated by the light source device, and emits the image projection light beam to project an image onto a screen. The image projecting unit includes an optical modulator, such as a liquid crystal panel, for modulating the light emitted from the lamp, and various optical elements through which the light from the lamp passes. 
         [0007]    The temperature of the light source device increases to a high temperature with light emission from the lamp, and the temperature of the image projecting unit is increased by the light received from the light source device by the optical modulator and the optical elements. 
         [0008]    Hence, the light source device and the image projecting unit are cooled by cooling air in order to achieve stable operations and longer lives of the light source device and the image projecting unit. 
         [0009]    Accordingly, a cooling device is provided in the projector apparatus of the related art. The cooling device guides outside air into the housing to cool the light source device and the image projecting unit, and exhausts the outside air after cooling. 
         [0010]    As such a cooling device, a cooling device including an air inlet and an air outlet provided in a housing, a plate-shaped air filter provided near the air inlet, and a fan has been proposed. 
         [0011]    The fan sucks outside air into the housing from the air inlet via the air filter, and exhausts the outside air from the housing through the air outlet after the outside air cools the light source device and the image projecting unit. 
         [0012]    The air filter filters outside air to remove dust from the outside air, and thereby prevents dust from adhering to the light source device and the image projecting unit. 
         [0013]    Unfortunately, dust accumulates on the air filter as the operating time of the cooling device elapses, and clogs the air filter eventually. 
         [0014]    When clogging occurs, the amount of air passing through the air filter decreases, and the cooling effect is reduced. As a result, it is difficult to sufficiently cool the light source device and the image projecting unit. 
         [0015]    For this reason, an operation of detaching a cover from the housing and replacing the air filter in the housing is performed frequently. This operation of replacing the air filter is troublesome to the user. 
         [0016]    Accordingly, Japanese Unexamined Patent Application Publication No. 8-1152242 discloses a projector apparatus in which an air filter is wound around a supply roll and is paid out from the supply roll when used. 
         [0017]    In this projector apparatus, a portion of the air filter clogged with adhering dust is sequentially wound around a take-up roll so that an unused portion of the air filter can be used. 
       SUMMARY OF THE INVENTION 
       [0018]    However, outside air that passes through the air inlet and the air filter and flows in the housing is not uniformly distributed over the entire surface of the air filter, and often concentrates at a part of the surface of the air filter. 
         [0019]    For this reason, dust contained in the outside air concentrates at a part of the air filter, and the air filter is apt to be partly clogged with dust. 
         [0020]    In this case, the amount of air passing through the air filter decreases although the other part of the air filter is not clogged, and therefore, the cooling effect decreases. 
         [0021]    Consequently, the clogged part of the air filter is wound up to use an unused portion of the air filter, and this wastes the air filter, in other words, a filter member. 
         [0022]    The present invention has been made in view of these circumstances, and it is desirable to provide a projector apparatus that advantageously suppresses reduction of a cooling effect and extends the life of a filter member. 
         [0023]    A projector apparatus according to an embodiment of the present invention includes a housing having an air inlet and an air outlet: a light source device provided in the housing; an image projection unit provided in the housing and configured to generate an image projection light beam from light from the light source device and to emit the image projection light beam so as to project an image onto a screen; and a cooling device configured to cool the light source device and the image projecting unit. The cooling device includes a cooling passage extending from the air inlet to the air outlet through an air filter section, the light source device, and the image projecting unit, and a fan configured to suck in outside air from the air inlet, to cause the outside air to flow through the cooling passage, and to exhaust the outside air out of the housing from the air outlet. The air filter section includes a cylindrical filter body, a filter support member configured to support the filter body, and a rotating unit configured to rotate the filter support member on a center axis of the filter body. In the air filter section, after the outside air flows from an outer peripheral surface to an inner peripheral portion of the filter body and dust is removed from the outside air by the filter body, the outside air flows out of the filter body in an axial direction of the filter body. 
         [0024]    According to the embodiment of the present invention, the filter body is cylindrical, and is rotated by the rotating unit. 
         [0025]    Hence, even when the amount of outside air passing through the filter body is not uniformly distributed on the outer peripheral surface of the filter body, but concentrates at a part of the outer peripheral surface, concentration of dust at the part of the filter body is suppressed by the rotation of the filter body. 
         [0026]    Therefore, the amount of air passing through the air filter does not easily decrease even during a long use period of the filter body. This advantageously suppresses reduction of the cooling effect, and extends the life of the filter body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a perspective view of a projector apparatus according to an embodiment of the present invention; 
           [0028]      FIG. 2  is a plan view of the projector apparatus shown in  FIG. 1 ; 
           [0029]      FIG. 3  is a front view of the projector apparatus; 
           [0030]      FIG. 4  is a structural view of the projector apparatus; 
           [0031]      FIG. 5A  is a front view of an air filter section,  FIG. 5B  is a view on arrow VB of  FIG. 5A , and  FIG. 5C  is a view on arrow VC of  FIG. 5A ; 
           [0032]      FIG. 6  is a front view illustrating a state in which a cover plate of a filter storage chamber is closed; 
           [0033]      FIG. 7  is a front view illustrating a state in which the cover plate of the filter storage chamber is open; 
           [0034]      FIG. 8  is a side view illustrating a state in which the cover plate of the filter storage chamber is closed; 
           [0035]      FIG. 9  is a side view illustrating a state in which the cover plate of the filter storage chamber is open; 
           [0036]      FIG. 10A  is a front view of a filter body supported by a filter support member,  FIG. 10B  is a view on arrow XA of  FIG. 10A , and  FIG. 100  is a view on arrow XB of  FIG. 10A ; 
           [0037]      FIG. 11  is a sectional view taken along line XIA-XIA in  FIG. 10A , and  FIG. 11B  is a sectional view taken along line XIB-XIB in  FIG. 10B ; 
           [0038]      FIG. 12  is an explanatory view illustrating structures of a brush and a dust chamber; 
           [0039]      FIG. 13  is an explanatory view illustrating structures of a brush and a dust chamber according to a second embodiment; 
           [0040]      FIG. 14  is an explanatory view illustrating a structure of an air filter section according to a third embodiment; and 
           [0041]      FIG. 15  is an explanatory view illustrating a structure of an air filter section according to a fourth embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       [0042]    Next, a first embodiment of the present invention will be described with reference to  FIGS. 1 to 12 . 
         [0043]    As shown in  FIGS. 1 to 3 , a projector apparatus  10  of the first embodiment includes a housing  12 , a light source device  14 , an image projecting unit  16 , and a cooling device  18 . 
         [0044]    The housing  12  is shaped like a flat rectangular plate having a height, a length larger than the height, and a width larger than the length. The housing  12  includes a front surface  12 A, a rear surface  12 B, an upper surface  12 C, a lower surface  12 D, and left and right surfaces  12 E and  12 F. 
         [0045]    In the first embodiment, in a state in which the projector apparatus  10  is viewed from a screen  2 , a side of the screen  2  is referred to as a front side, and an opposite side is referred to as a rear side. Right and left sides are referred to as right and left sides provided when the projector apparatus  10  is viewed from the front side. 
         [0046]    A lens barrel  34  is provided at almost the widthwise center of the front surface  12 A. Air inlets  20  for taking outside air into the housing  12  are provided in the right surface  12 F. In the first embodiment, the air inlets  20  are formed by multiple slits provided in the right surface  12 F. 
         [0047]    Air outlets  22  for exhausting air from the housing  12  are provided in the left surface  12 E. In the first embodiment, the air outlets  22  are formed by multiple slits provided over the entire left surface  12 E. 
         [0048]    As shown in  FIGS. 2 and 3 , the light source device  14 , the image projecting unit  16 , and the cooling device  18  are contained in the housing  12 . In the first embodiment, the light source device  14 , the image projecting unit  16 , and the cooling device  18  are arranged in this order from left to right in the width direction of the housing  12  in plan view. 
         [0049]    Referring to  FIG. 4 , the light source device  14  includes a power supply unit  14 A and a lamp  14 B. The power supply unit  14 A supplies power to the lamp  14 B. The lamp  14 B is driven by power supplied from the power supply unit  14 A so as to generate image projection light, and adopts a white light source for emitting light having a visible spectrum. As the lamp  14 B, various continuous spectrum light sources of the related art, such as a xenon lamp, a high-pressure mercury lamp, and a metal halide lamp, can be used. 
         [0050]    Since the temperature of the lamp  14 B increases to a high temperature with light emission, the lamp  14 B is cooled by cooling air in order to ensure a high brightness (in other words, stable operation) and a longer life thereof. 
         [0051]    As shown in  FIG. 4 , the image projecting unit  16  produces an image projection light beam using light from the light source device  14 , and emits the image projection light beam to project an image onto the screen  2 . 
         [0052]    The image projecting unit  16  includes an illumination optical unit  24 , a separation unit  26 , an image modulation unit  28 , an image synthesizing unit  30 , and a projection optical system  32 . 
         [0053]    The illumination optical unit  24  blocks part of light emitted from the light source device  14  to make the illuminance of the light uniform, and guides the light to the separation unit  26 . 
         [0054]    In the first embodiment, the illumination optical unit  24  includes an ultraviolet-infrared cut filter  24  for blocking ultraviolet and infrared rays, two fly-eye lenses  24 B and  24 C for making the illuminance of light uniform, a polarization conversion element  24 D, and a condenser lens  24 E. 
         [0055]    By blocking ultraviolet and infrared rays contained in the light emitted from the light source device  14  with the ultraviolet-infrared cut filter  24 A, various optical components that form the separation unit  26 , the image modulation unit  28 , the image synthesizing unit  30 , and the projection optical system  32  are prevented from heating and degradation. 
         [0056]    The separation unit  26  separates light (white light), which is guided from the illumination optical unit  24  and has a uniform illuminance, into light beams of three colors of red (R), green (G), and blue (B). For example, the separation unit  26  includes a plurality of dichroic mirrors and so on. 
         [0057]    More specifically, in the first embodiment, the separation unit  26  includes first and second dichroic mirrors  2602  and  2604 , and first to third mirrors  2606 ,  2608 , and  2610 . 
         [0058]    The first dichroic mirror  2602  transmits red and green light beams R and G, of the light guided from the illumination optical unit  24 , and reflects a blue light beam B. 
         [0059]    The second dichroic mirror  2604  transmits the red light beam R, of the red and green light beams R and G passing through the first dichroic mirror  2602 , and reflects the green light beam G. 
         [0060]    Thus, the light guided from the illumination optical unit  24  to the first dichroic mirror  2602  is separated into two light beams, that is, the blue light beam B and the red/green light beam R/G by the first dichroic mirror  2602 . 
         [0061]    The blue light beam B separated by the first dichroic mirror  2602  is reflected by the first mirror  2606 . 
         [0062]    The green light beam G, of the red/green light beam R/G separated by the first dichroic mirror  2602 , reaches the second dichroic mirror  2604 . 
         [0063]    The red light beam R, of the red/green light beam R/G separated by the first dichroic mirror  2602 , passes through the second dichroic mirror  2604 , reaches the third mirror  2610  via the second mirror  2608 , and is reflected by the third dichroic mirror  2610 . 
         [0064]    The red, green, and blue light beams R, G, and B thus separated by the separation unit  26  are emitted from the separation unit  26  toward the image modulation unit  28 . 
         [0065]    The separation unit  26  can adopt various structures of the related art as long as it has a function of separating light (white light) guided from the illumination optical unit  24  into light beams of three colors, red, green, and blue R, G, and B. 
         [0066]    The image modulation unit  28  modulates the three light beams R, G, and B guided from the separation unit  26  according to image information, and supplies the modulated light beams to the image synthesizing unit  30 . 
         [0067]    The image modulation unit  28  includes first to third image modulation elements  28 R,  28 G, and  28 B corresponding to the three light beams R, G, and B. In the first embodiment, the first to third image modulation elements  28 R,  28 G, and  28 B are formed by transmissive liquid crystal display devices (liquid crystal light valves). Each liquid crystal display device includes a device body having two transparent substrates between which a liquid crystal layer is sealed, and a polarizing plate incorporated in the device body. 
         [0068]    The first to third image modulation elements  28 R,  28 G, and  28 B have display surfaces, and display images on the display surfaces by receiving image signals (driving signals) corresponding to information about three color images of red, green, and blue. 
         [0069]    The red light beam R emitted from the separation unit  26  to the image modulation unit  28  is modulated according to the image information when passing through the first image modulation element  28 R, and is guided to the image synthesizing unit  30 . 
         [0070]    The green light beam G emitted from the separation unit  26  to the image modulation unit  28  is modulated according to the image information when passing through the second image modulation element  28 G, and is guided to the image synthesizing unit  30 . 
         [0071]    The blue light beam B emitted from the separation unit  26  to the image modulation unit  28  is modulated according to the image information when passing through the third image modulation element  28 B, and is guided to the image synthesizing unit  30 . 
         [0072]    The first to third image modulation elements  28 R,  28 G, and  28 B may be formed by reflective liquid crystal display devices or various image display devices of the related art, instead of the transmissive liquid crystal display devices. The image display devices are not limited to the above-described liquid crystal display devices, and may be formed by various types of image display devices of the related art. 
         [0073]    The image synthesizing unit  30  generates one image projection light beam by synthesizing the three light beams R, G, and B modulated by the image modulation unit  28 , and guides the image projection light beam to the projection optical system  32 . In the first embodiment, the image synthesizing unit  30  is formed by a crossed prism  30 A. 
         [0074]    The crossed prism  30 A includes three incident surfaces  3002 ,  3004 , and  3006  on which the light beams from the first to third image modulation elements  28 R,  28 G, and  28 B are incident, respectively. The incident surfaces  3002 ,  3004 , and  3006  are orthogonal to one another. 
         [0075]    The crossed prism  30 A also includes an emitting surface  3008  from which the image projection light beam generated by synthesizing the three light beams R, G, and B is emitted. 
         [0076]    The image synthesizing unit  30  is not limited to the crossed prism  30 A as long as it can generate one image projection light beam by synthesizing three light beams R, G, and B. The image synthesizing unit  30  may be formed by various optical elements of the related art. 
         [0077]    The projection optical system  32  receives the image projection light beam guided from the image synthesizing unit  30 , and projects the image projection light beam onto the screen  2 . The projection optical system  32  includes a plurality of lenses. 
         [0078]    In the first embodiment, the projection optical system  32  is housed in the above-described lens barrel  34 , and the front of the lens barrel  34  protrudes frontward from the front surface  12 A of the housing  12 . 
         [0079]    The temperatures of the illumination optical unit  24 , the separation unit  26 , the image modulation unit  28 , the image synthesizing unit  30 , and the projection optical system  32 , which constitute the image projecting unit  16 , are increased to high temperatures by passage of the light emitted from the lamp  14 B. 
         [0080]    Therefore, these components are cooled by cooling air in order to stabilize the operations of the components and to extend the lives of the components. 
         [0081]    Next, the cooling device  18  that is the gist of the embodiment of the present invention will be described. 
         [0082]    As shown in  FIGS. 1 to 3 , the cooling device  18  includes an air filter section  36 , a cooling passage  38 , and a fan  40 . 
         [0083]    The cooling passage  38  is a passage through which outside air flows in the housing  12 , and extends from the air inlets  20  to the air outlets  22  via the air filter section  36 , the light source device  14 , and the image projecting unit  16 . 
         [0084]    The fan  40  sucks in outside air through the air inlets  20 , causes the outside air to flow through the cooling passage  38 , and exhausts the outside air out of the housing  12  through the air outlets  22 . 
         [0085]    In the first embodiment, the fan  40  is formed by a sirocco fan having rotary blades. The fan  40  sucks in air in the axial direction of the rotary blades and exhausts the air outside in the radial direction of the rotary blades. 
         [0086]    The fan  40  is provided in the right rear of the housing  12  in a manner such that the axial direction of the rotary blades coincides with the front-rear direction of the housing  12 . The fan  40  includes a suction port  40 A (suction duct) from which air is sucked in, and an exhaust port from which air is exhausted. 
         [0087]    The fan  40  can be formed not only by the sirocco fan, but also by various fans of the related art, for example, an axial fan. 
         [0088]    As shown in  FIGS. 2 and 5 , the air filter section  36  includes a filter storage chamber  42 , a filter body  44 , a filter support member  46 , and a rotating unit  48 . 
         [0089]      FIG. 10A  is a front view of the filter body  44  supported by the filter support member  46 ,  FIG. 10B  is a view on arrow XA of  FIG. 10A , and  FIG. 10C  is a view on arrow XB of  FIG. 10A .  FIG. 11A  is a cross-sectional view taken along line XIA-XIA in  FIG. 10A , and  FIG. 11B  is a cross-sectional view taken along line XIB-XIB in  FIG. 10B . 
         [0090]    As shown in  FIGS. 10 and 11 , the filter body  44  is cylindrical. This filter body  44  can be formed of various synthetic resin materials of the related art, for example, urethane foam. Further, an electrostatic filter for use in an air cleaning device can be used as the filter body  44 . 
         [0091]    Alternatively, the filter body  44  may be shaped like a so-called bellows bent by alternately forming peaks and troughs, which extend parallel to the center axis of the filter body  44 , in the circumferential direction. 
         [0092]    The filter support member  46  supports the filter body  44 . As shown in  FIGS. 11A and 11B , the filter support member  46  includes a cylindrical body  46 A formed by a punched metal having multiple holes, and annular plate portions  46 B and  46 C attached to opposite ends of the cylindrical body  46 A. 
         [0093]    The annular plate portions  46 B and  46 C extend in an annular form and coaxially with the filter body  44 . 
         [0094]    Instead of the punched metal, the cylindrical body  46 A can be formed of various materials of the related art that allow air circulation, for example, a mesh structure and a structure having multiple slits. 
         [0095]    The cylindrical body  46 A and the annular plate portions  46 B and  46 C are coaxially provided, and the filter body  44  is mounted on the cylindrical body  46 A. 
         [0096]    In a state in which the filter body  44  is mounted on the cylindrical body  46 A, the annular plate portions  46 B and  46 C are exposed from opposite axial ends of the filter body  44 . 
         [0097]    One annular plate portion  46 B is provided with its end face closed, and the other annular plate portion  46 C has an aperture  4602  in its end face. The suction port (suction duct)  40 A of the fan  40  is fitted in the filter support member  46  through the aperture  4602 . 
         [0098]    Referring to  FIGS. 100 and 11B , a gasket  47  is attached to the entire inner peripheral surface of the aperture  4602 , and fills the gap between the aperture  4602  and the suction port  40 A. The gasket  47  can be formed of various synthetic resin materials of the related art, for example, urethane foam. 
         [0099]      FIG. 6  is a front view illustrating a state in which a cover plate  50  of the filter storage chamber  42  is closed, and  FIG. 7  is a front view illustrating a state in which the cover plate  50  is open.  FIG. 8  is a side view illustrating the state in which the cover plate  50  is closed, and  FIG. 9  is a side view illustrating the state in which the cover plate  50  is open. 
         [0100]    As shown in  FIGS. 6 to 9 , the filter storage chamber  42  stores the filter body  44  and the filter support member  46 , and is opened and closed by the cover plate  50 . 
         [0101]    The cover plate  50  includes an upper face portion  50 A to face an upper side of an outer peripheral surface of the filter body  44 , and a side face portion  50 B to face a vertical middle portion of the outer peripheral surface of the filter body  44 . 
         [0102]    A portion of the upper face portion  50 A opposite the side face portion  50 B is pivotally coupled to the housing  12  by a hinge  50 C. 
         [0103]    In the first embodiment, the upper face portion  50 A forms a right side portion of the upper surface  12 C of the housing  12 , and the side face portion  50 B forms most of the right surface  12 F of the housing  12 . Further, the above-described slits that form the air inlets  20  are provided over the entire side face portion  50 B. 
         [0104]    Referring to  FIGS. 6 to 9 , the rotating unit  48  rotates the filter support member  46  on the center axis of the filter body  44 . 
         [0105]    The rotating unit  48  have, at a plurality of positions spaced in the circumferential directions of the annular plate portions  46 B and  46 C, a plurality of rollers  52  that are in rotating contact with the annular plate portions  46 B and  46 C so as to support the filter support member  46  rotatably. 
         [0106]    The rollers  52  include upper rollers  52 A in contact with the upper portions of the annular plate portions  46 B and  46 C, side rollers  52 B and  52 C provided on two sides to be in contact with the vertical middle portions of the annular plate portions  46 B and  46 C, and lower rollers  52 D in contact with the lower portions of the annular plate portions  46 B and  46 C. 
         [0107]    In the first embodiment, the lower rollers  52 D are driven rotationally. The lower rollers  52 D may be rotated by elastic contact with a driving roller  54  attached to an output shaft of a motor (not shown), or by coupling to a belt pulley mechanism  56 , as shown in  FIG. 3 . 
         [0108]    The timing, frequency, and time period of rotation of the filter body  44  by the rotating unit  48  can be determined arbitrarily. 
         [0109]    For example, the filter body  44  may be rotated for a predetermined time at power-on of the projector apparatus  10 . Alternatively, the filter body  44  may be continuously or intermittently rotated during operation of the projector apparatus  10 . 
         [0110]    The upper rollers  52 A and the side rollers  52 C are rotatably supported by the cover plate  50 . The lower rollers  52 D and the other side rollers  52 B are rotatably supported by the housing  12 . 
         [0111]    When the cover plate  50  is opened, the upper rollers  52 A and the side rollers  52 C are placed above the filter storage chamber  42 , so that the filter support member  46  on which the filter body  44  is mounted can be inserted and removed. 
         [0112]    Since the filter body  44  and the filter support member  46  can thus be replaced by an extremely easy operation of opening the cover plate  50 , maintenance is facilitated. 
         [0113]    In  FIGS. 6 to 9 , a plurality of regulation rollers  58  regulate the movement of the filter support member  46  in the axial direction of the filter body  44  by being in contact with the end faces of the annular plate portions  46 B and  46 C. These regulation rollers  58  are provided in the housing  12 . 
         [0114]    In the air filter section  36 , outside air reaches an inner peripheral portion from an outer peripheral surface of the filter body  44 , where dust is removed from the outside air by the filter body  44 . The outside air then flows in the axial direction of the filter body  44 , and comes out of the filter body  44 . In the first embodiment, the outside air coming out of the interior of the filter body  44  flows through the cooling passage  38  via the suction port  40 A and the exhaust port of the fan  40 . 
         [0115]    Referring to  FIG. 12 , the air filter section  36  further includes a brush  60  and a dust receiving portion  62 . 
         [0116]    The brush  60  is provided via a support member  64  in a manner such as to be in contact with the outer peripheral surface of the filter body  44 . More specifically, a leading end portion of the brush  60  linearly extends parallel to the center axis of the filter body  44  over the entire length of the filter body  44 . 
         [0117]    The dust receiving portion  62  receives dust scraped off by the brush  60 . The dust receiving portion  62  is provided on an upstream side of the brush  60  in the rotating direction of the outer peripheral surface of the filter body  44 , and at the bottom of the housing  12  with a wall  66  being disposed therebetween. 
         [0118]    Hence, when the filter body  44  rotates, dust adhering to the outer peripheral surface of the filter body  44 , especially relatively large dust, such as fluff, is scraped off by the brush  60 , and is put into the dust receiving portion  62 . 
         [0119]    A portion including the dust receiving portion  62 , the support member  64 , the wall  66  (a portion of the bottom of the housing  12 ) may be detachable from the housing  12 . With this structure, maintenance operations, such as removal of dust from the dust receiving portion  62  and cleaning and washing of the brush  60 , can be performed easily. 
         [0120]    Next, the operation of the cooling device  18  will be described. 
         [0121]    When the projector apparatus  10  is powered on, the fan  40  of the cooling device  18  rotates. 
         [0122]    By rotation of the fan  40 , outside air is taken into the housing  12  through the air inlets  20 . 
         [0123]    The air taken in the housing  12  flows from the outer peripheral surface to the inner peripheral portion of the filter body  44 , where dust is removed from the air by the filter body  44 . Then, the air is sucked into the suction port  40 A of the fan  40 . 
         [0124]    The sucked air flows through the remaining portion of the cooling passage  38  via the exhaust port of the fan  40 , that is, flows through the light source device  14  and the image projecting unit  16 , thereby cooling the light source device  14  and the image projecting unit  16 . 
         [0125]    After cooling the light source device  14  and the image projecting unit  16 , the air is exhausted from the housing  12  through the air outlets  22 . 
         [0126]    In this case, every time the filter body  44  is rotated by the rotating unit  48 , the portion of the filter body  44  where the outside air flows from the outer peripheral surface to the inner peripheral portion of the filter body  44  changes. 
         [0127]    According to the first embodiment, the filter body  44  is cylindrical and is rotated by rotating the filter support member  46  on the center axis of the filter body  44 . For this reason, even if the amount of outside air flowing through the filter body  44  is not uniformly distributed on the outer peripheral surface of the filter body  44 , but concentrates at a certain portion, concentration of dust at a portion of the filter body  44  is suppressed by the rotation of the filter body  44 . 
         [0128]    Hence, dust uniformly adheres to the entire filter body  44 , and partial clogging of the filter body  44  due to dust rarely occurs. Accordingly, even when the filter body  44  is used for a long period, the amount of passing air does not easily decrease, and this suppresses reduction of the cooling effect and extends the life of the filter body  44 , in other words, the filter member. 
         [0129]    Further, since the filter body  44  is cylindrical, size reduction of the illumination optical unit  24  and size reduction of the projector apparatus  10  can be achieved while ensuring the surface area of the filter body  44 . 
         [0130]    Still further, since the filter body  44  is cylindrical, the surface area of the filter body  44  is ensured. For this reason, even if the rotation of the filter body  44  is stopped by trouble of the rotating unit  48 , clogging with dust will not occur in a short time. 
         [0131]    Since the fan  40  communicates with the inner peripheral portion of the filter body  44  via the suction port  40 A, noise caused by the fan  40  can be suppressed by the sound absorbing effect of the filter body  44 , and this achieves noise reduction of the projector apparatus  10 . 
         [0132]    While the air inlets  20  are provided in the side face portion  50 B facing the vertical middle portion of the outer peripheral surface of the filter body  44  in the first embodiment, since the filter body  44  is cylindrical, air inlets  20  can be added in the upper surface  12 C of the housing  12  facing the upper side of the filter body  44  or the lower surface  12 D of the housing  12  facing the lower side of the filter body  44 . 
         [0133]    By thus forming the air inlets  20  at a plurality of positions, the amount of outside air to be sucked into the housing  12  is increased and the cooling ability of the cooling device  18  is enhanced. 
         [0134]    Air inlets  20  may be added in the front surface  12 A of the housing  12  facing the annular plate portion  46 B. In this case, the amount of outside air to be sucked into the housing  12  is further increased, and the cooling ability of the cooling device  18  is further enhanced. 
       Second Embodiment 
       [0135]    Next, a second embodiment will be described. 
         [0136]      FIG. 13  illustrates structures of a brush  60  and a dust receiving portion  62  in the second embodiment. In the second embodiment, components identical or similar to those adopted in the first embodiment are denoted by the same reference numerals, and redundant descriptions thereof are omitted. 
         [0137]    The second embodiment is a modification of the first embodiment, and is different from the first embodiment in the structure of the dust receiving portion  62 . 
         [0138]    A rotating unit  48  ( FIG. 5 ) rotates a filter support member  46  in forward and reverse directions. 
         [0139]    As shown in  FIG. 13 , the dust receiving portion  62  is provided on each of the upstream and downstream sides, in the rotating direction of an outer peripheral surface of a filter body  44 , of a position where the brush  60  is in contact with the outer peripheral surface. 
         [0140]    The above-described second embodiment provides advantages similar to those of the first embodiment. 
         [0141]    Further, since the filter support member  46  is rotated in the forward and reverse directions, dust adhering to the outer peripheral surface of the filter body  44  is scraped off by the brush  60  and is put into the two dust receiving portions  62 , regardless of the rotating direction of the filter body  44 . 
         [0142]    Hence, more dust can be reliably received by the two dust receiving portions  62  than in the first embodiment, and this reduces the load of maintenance of the dust receiving portions  62 . 
       Third Embodiment 
       [0143]    Next, a third embodiment will be described. 
         [0144]      FIG. 14  illustrates a structure of an air filter section  36  in the third embodiment. 
         [0145]    The third embodiment is a modification of the first embodiment, and is different from the first embodiment in a structure of a rotating unit. 
         [0146]    As shown in  FIG. 14 , a rotating unit  70  includes a base  72  and a driving roller  74 . 
         [0147]    The base  72  is shaped like an annular plate, and is rotatably supported by a housing  12 . An opening  72 A in which a suction port  40 A of a fan  40  is fitted is provided in the center of the base  72 . To fill the gap between an inner peripheral surface of the opening  72 A and the suction port  40 A, a gasket (not shown) is provided over the entire inner peripheral surface of the opening  72 A. This gasket prevents air that does not pass through the filter body  44  from being guided to the suction port  40 A from the gap. 
         [0148]    One annular plate portion  46 C of a filter support member  46  is combined with the base  72  by screws N in a state in which the center axis of the annular plate portion  46 C coincides with the center axis of the base  72 . 
         [0149]    The driving roller  74  is attached to an output shaft of a motor (not shown), and is in contact with an outer peripheral surface of the base  72 . 
         [0150]    When the driving roller  74  is rotated by the motor, this rotation rotates the filter support member  46  and the filter body  44  via the base  72 . 
         [0151]    The above-described third embodiment provides advantages similar to those of the first embodiment. 
         [0152]    Further, since the third embodiment does not use a plurality of rollers for rotatably supporting the filter body  44 , unlike the rotating unit  48  of the first embodiment, the structure is simplified, and size reduction is achieved. 
       Fourth Embodiment 
       [0153]    Next, a fourth embodiment will be described. 
         [0154]      FIG. 15  illustrates a structure of an air filter section  36  in the fourth embodiment. 
         [0155]    The fourth embodiment is a modification of the third embodiment, and is different from the third embodiment in a structure of a rotating unit. 
         [0156]    As shown in  FIG. 15 , a rotating unit  80  includes a base  72 , a driving roller  74 , a male thread portion  82 , and a female thread portion  84 . 
         [0157]    The base  72  and the driving roller  74  have structures similar to those in the third embodiment. 
         [0158]    The male thread portion  82  is shaped like a cylinder coaxial with the base  72 , and has an inner peripheral surface that surrounds a suction port  40 A of a fan  40 . 
         [0159]    The female thread portion  84  is provided in one annular plate portion  46 C of a filter support member  46 , and is screwed on the male thread portion  82 . 
         [0160]    By screwing the female thread portion  84  of the annular plate portion  46 C on the male thread portion  82  of the base  72 , the filter support member  46  is combined with the base  72  in a state in which the center axis of the filter support member  46  coincides with the center axis of the base  72 . 
         [0161]    When the driving roller  74  is rotated by a motor (not shown), this rotation rotates the filter support member  46  and a filter body  44  via the base  72 . 
         [0162]    The above-described fourth embodiment provides advantages similar to those of the third embodiment. 
         [0163]    While the single air filter section  36  is provided in the embodiments, two or more air filter sections can, of course, be provided. 
         [0164]    The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-141005 filed in the Japan Patent Office on Jun. 12, 2009, the entire content of which is hereby incorporated by reference. 
         [0165]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.