Abstract:
A projector which includes a first exhaust fan discharging exhaust air from a light source lamp to exterior and a second exhaust fan discharging exhaust air from parts other than the light source lamp are arranged to be adjacent to each other. An end of the exhaust fan facing the other exhaust fan is moved to the inner side and the one exhaust fan is inclined to discharge air in an exhaust direction toward a direction along which air is discharged from the other exhaust fan. There is provided a cooling fan that blows air to an interior air blow outlet communicating with the interior of the light source lamp and exterior air blow outlets communicating with an outer surface to cool the light source lamp. The exterior air blow outlets are deviated from the center of the outer surface of the light source lamp.

Description:
FIELD OF THE INVENTION 
     The invention of the present application relates to a projection type image display apparatus that modulates light emitted from a light source lamp based on an image signal to project the modulated image light in an expanded manner. In particular, the invention relates to a structure for cooling the light source lamp and a structure for exhausting heat in the apparatus. 
     BACKGROUND OF THE INVENTION 
     A projection type image display apparatus of a liquid crystal projector for example is required to achieve both of a higher output of a light source lamp and a minimization. Thus, a luminous tube in a reflector of a light source lamp uses a high-pressure mercury lamp or a metal halide lamp for example that emits light with a high intensity at a high temperature. However, a part of the light source lamp having the highest temperature is heated to a temperature of about 1000° C. and thus the light source lamp is cooled by air blown from a fan. This light source lamp exhausts air of a high temperature that is higher than that of a power source unit. Thus, the high temperature is solved by maximizing the capability of the exhaust fan (rotating speed), by increasing the size of the exhaust fan, or by providing a plurality of exhaust fans. 
     Japanese Patent Laid-Open Publication No. H09-90511 (Patent Publication 1) discloses a projection type image display apparatus having a fan for cooling a light source lamp in which a part of a duct extending from this fan to a light source lamp that is opposed to the light source lamp includes an opening (air blow outlet). Japanese Patent Laid-Open Publication No. 2000-19644 (Patent Publication 2) discloses a projection type image display apparatus structured so that two exhaust fans are provided in parallel to each other in the vicinity of a light source lamp to discharge exhaust air from the light source lamp or a power source unit for example. 
     However, in the above conventional light source lamp cooling mechanism as disclosed in Patent Publication 1, the fan and the air blow outlet are arranged in consideration of only the cooling of the light source lamp. Thus, when this structure cools the light source lamp, this structure causes a proportional increase in the temperature of the exhaust air. An excessively-high exhaust air temperature causes an increased number of complaints from users. Furthermore, the structure of Patent Publication 2 requires an increased interval between a side wall of a housing and the exhaust fans arranged to be parallel to each other, thus hindering the structure from being minimized. For reducing the temperature of the exhaust air, a structure may be considered in which exhaust air of a high temperature from the light source lamp and exhaust air of a low temperature from the power source unit for example can be mixed by inclining the respective exhaust fans arranged to be parallel to each other to form an inverted V-like shape in the exhaust directions thereof. However, this structure also requires a space and thus is hindered from being minimized. 
     In the conventional technique as described above, the cooling of the light source lamp having a high output causes an increased temperature of an exhaust air, which exceeds a permissible range of users, thus making it difficult to achieve both of the cooling of the light source lamp and the reduction of the exhaust air temperature. When the difficulty is tried to be solved by increasing the output of the fan or by increasing the number of fans, a disadvantage is caused in which noise is increased or the apparatus is prevented from being minimized. 
     SUMMARY OF THE INVENTION 
     The invention of the present application has been made in view of the point as described above. It is an objective of the invention to provide a projection type image display apparatus that achieves the cooling of the light source lamp and the reduction of the exhaust air temperature and that can be minimized while reducing the noise from the exhaust fan. 
     In order to achieve the above objective, the invention of the present application is characterized in a projection type image display apparatus that modulates light emitted from a light source lamp based on an image signal to project the modulated image light in an expanded manner. The projection type image display apparatus is including a first exhaust fan for mainly discharging exhaust air from the light source lamp to exterior, and a second exhaust fan for mainly discharging exhaust air from parts other than the light source lamp to exterior that are arranged to be parallel to each other. These fans are arranged so that an end of one exhaust fan facing the other exhaust fan is moved to the inner side and the one exhaust fan is inclined to discharge air in an exhaust direction toward a direction along which air is discharged from the other exhaust fan. 
     According to this structure, an end of one exhaust fan facing the other exhaust fan is moved to the inner side. This structure can form an interval between a side wall of a housing and the one exhaust fan without hindering the structure from be minimized and can reduce noise. This structure also can mix the exhaust air of a high temperature from the light source lamp with the exhaust air of a relatively low temperature from parts other than the light source lamp, thus reducing the temperature of the exhaust air. 
     In this case, a space can be obtained between the light source lamp and the second fan. Thus, an end of the first exhaust fan facing the second exhaust fan is preferably moved to the inner side, and the first exhaust fan is inclined to have the exhaust direction facing the exhaust side of the second exhaust fan. 
     The second exhaust fan is preferably structured to mainly discharge exhaust air from the power source unit to exterior. 
     This structure also can simultaneously perform the discharge of exhaust air from an important power source unit that has a temperature not so high as the light source lamp. 
     The first exhaust fan is preferably inclined to an exhaust hole formed in the side wall of the housing. 
     This structure can allow exhaust air of a high temperature from the light source lamp to be discharged through the exhaust hole in an inclined direction. Thus, the exhaust air is proportionally difficultly discharged therethrough and thus can be easily mixed with the exhaust air of a relatively low temperature from the second exhaust fan. Thus, the exhaust air temperature can be further reduced. 
     The first exhaust fan is preferably inclined so that the exhaust air is discharged through the exhaust hole formed in the side wall of the housing to the front side in an inclined direction. 
     This structure can prevent the exhaust air having a high temperature from being blown in a lateral direction leading to a user. 
     In the present invention, it is preferable that a cooling fan that blows air to an interior air blow outlet communicating with the interior of the light source lamp and an exterior air blow outlet communicating with an outer surface to cool the light source lamp is provided. The exterior air blow outlet is deviated from the center of the outer surface of the light source lamp. The cooling fan is used to allow the exhaust air used for cooling the light source lamp to be discharged through the first exhaust fan. The first exhaust fan is inclined so that air is sucked by the first exhaust fan in a direction to the exterior air blow outlet. 
     According to the above structure, the interior of the light source lamp having a luminous tube of the highest temperature can be efficiently cooled by the interior air blow outlet. The outer surface of the light source lamp having a temperature not so high as the interior of the light source lamp can be appropriately cooled by the exterior air blow outlet deviated from the center of the outer surface. Furthermore, the first exhaust fan is inclined so that air is sucked by the first exhaust fan in a direction to the exterior air blow outlet. Thus, air blown through the exterior air blow outlet deviated from the center of the outer surface of the light source lamp cools the outer surface of the light source lamp and a part thereof is directly sucked by the first exhaust fan and is mixed with exhaust air having the temperature elevated by cooling the interior of the light source lamp, and is exhausted to exterior. Thus, the temperature of the exhaust air can be reduced. Thus, both of the cooling of the light source lamp and the reduction of the exhaust air temperature can be achieved without excessively increasing the output of the fan and noise can be reduced. 
     In this case, the exterior air blow outlet is preferably deviated from the center of the outer surface of the light source lamp and is divided into two parts, consisting of upper and lower parts. 
     The above structure can cool the outer surface of the light source lamp in a substantially uniform manner. 
     A degree at which the exterior air blow outlet is deviated from the center of the outer surface of the light source lamp and a degree at which the second fan is inclined so that air is sucked by the second fan in a direction to the exterior air blow outlet are preferably determined in consideration of the cooling of the light source lamp and the exhaust air temperature. 
     The structure as described above can flexibly achieve both of the cooling of the light source lamp and the reduction of the exhaust air temperature in accordance with the light source lamp having a higher output or the apparatus being minimized. 
     The interior air blow outlet and the exterior air blow outlet are preferably formed in a duct extending from the first fan to the light source lamp. 
     The structure as described above can improve the freedom degree of the arrangement of the first fan. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a liquid crystal projector according to one embodiment of a projection type image display apparatus of the present invention, obliquely seen from above from the front side. 
         FIG. 2  is similarly a perspective view obliquely seen from above from the back side. 
         FIG. 3  is a perspective view in which an upper case in  FIG. 1  is removed. 
         FIG. 4  is a perspective view in which a main control substrate is further removed. 
         FIG. 5  is a perspective view in which an optical system is further removed. 
         FIG. 6  is a top plan view of  FIG. 5 . 
         FIG. 7  is a view showing a configuration example of an optical system. 
         FIG. 8  is an enlarged view of principal parts showing a light source lamp cooling mechanism in the present embodiment, and is also a perspective view obliquely seen from above from the front side. 
         FIG. 9  is similarly a perspective view in which an upper half of a duct is removed and obliquely seen from above from the back side. 
         FIG. 10  is a perspective view in which a holder of the light source lamp in  FIG. 9  is removed. 
         FIG. 11  is a cross-sectional view of the principal parts seen from the back side. 
         FIG. 12  is an enlarged view of the principal parts showing an optical part cooling mechanism in the present embodiment, and is also a perspective view obliquely seen from above from the front side. 
         FIG. 13  is similarly a top plan view. 
         FIG. 14  is similarly a top plan view in which the optical parts are removed. 
         FIG. 15  is similarly a back side view in which the lower half of the duct is removed. 
         FIG. 16  is a perspective view showing an exhaust fan unit constituting an exhaust mechanism in the present invention. 
         FIG. 17  is similarly a perspective view showing the back side. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     One embodiment of the present invention will now be described below in detail with reference to the drawings. 
       FIG. 1  is a perspective view of a liquid crystal projector as one embodiment of a projection type image display apparatus according to the present invention seen obliquely from above from the front side,  FIG. 2  is similarly a perspective view seen obliquely from above from the back side,  FIG. 3  is a perspective view in which the upper case in  FIG. 1  is removed,  FIG. 4  is a perspective view in which a main control substrate is further removed,  FIG. 5  is a perspective view in which an optical system is further removed, and  FIG. 6  is a top plan view of  FIG. 5 . 
     As shown in  FIGS. 1 and 2 , a housing  2  forming an outer hull of this liquid crystal projector  1  is compact, has a horizontally long thin rectangular shape, and consists of an upper case  2   a  and a lower case  2   b . When the upper case  2   a  and a main control substrate  3  are removed, the interior thereof is displayed as shown in  FIG. 4 . 
     The left side seen from the front side of the front wall of the upper case  2   a  is formed with a projection window  5 , from which a projection lens  4  is exposed. The left side front portion of the upper surface of the upper case  2   a  is formed with an operation window  6 , from which an adjustable dial  4   a  that adjusts zooming and focusing of the projection lens  4  corresponding to the projection window  5  is exposed. The left side back portion of the upper surface of the upper case  2   a  is provided with an operation display portion  7 . 
     On the other hand, the right side wall of the lower case  2   b  seen from the front side is formed with a plurality of slit-like exhaust holes  8 . Both side corner portions of the bottom front portion of the lower case  2   b  are provided with leg portions  9  adjustable in height. On the backside wall of the lower case  2   b , a power source inlet  10  connected to a power source plug and an inlet and outlet terminal group  11  to connect various types of input and output cables are exposed. 
     Inside the housing  2 , as shown in  FIGS. 3 and 4 , looking from the front side, the right side inner portion is disposed with a light source unit  12 , and at the same time, an optical system  13  reaching the projection lens  4  from the light source unit  12  is disposed approximately in L-shape. In front of the light source unit  12 , a power source main body  14  stored with a power source circuit substrate mounted with the circuit parts to feed a power source to each portion of the apparatus and a ballast circuit substrate mounted with circuit parts to feed the power supply exclusively to the light source lamp is disposed, and in the back of the light source unit  12 , a noise removal filter portion  15  to remove the noise infiltrating through the power source inlet  10  is disposed. 
     In the present embodiment, the noise removal filter portion  15  is separated from the power source unit main body  14 , and at the same time, the separated noise removal filter portion  15  is disposed to be positioned as closely as possible to the housing back side wall provided with the power source inlet  10  and the power source unit main body  14 . Specifically, along the front side wall of the horizontally long house  2 , the power source unit main body  14  is disposed, and at the position opposite to the power source unit main body  14  in the back side wall, the noise removal filter portion  15  mounted with a core (coil)  15   a  and the like on the substrate is disposed along the back side wall. 
     On the other hand, at the back side in an irradiating direction of the light source unit  12 , a suction fan  16  composed of a sirocco fan as a first fan including the light source lamp cooling mechanism is disposed, and at the lateral side, an exhaust fan  17  composed of an axial fan as a second fan constituting the light source lamp cooling mechanism is disposed. 
     At the lateral side of the power source unit main body  14 , an exhaust mechanism is provided. This exhaust mechanism is configured such that an exhaust fan  18  composed of the axial fan as a second exhaust fan is horizontally disposed side by side with the exhaust fan  17 . Incidentally, the exhaust fan  17  as the second fan constituting the light source lamp cooling mechanism serves as the first exhaust fan constituting the exhaust mechanism. 
       FIG. 7  is a view showing a configuration example of the optical system  13 . Incidentally, the optical system  13  is not limited to the one shown in  FIG. 7  and the present invention can be applied to the apparatuss provided with various types of optical systems. 
     In  FIG. 7 , a white light from the light source lamp  19  passes through a condenser lens  20 , a first integrator lens  21 , a second integrator lens  22 , a polarizing beam splitter (PBS)  23 , and a condenser lens  24  or the like, and is irradiated at a first dichroic mirror  25 . 
     The first integrator lens  21  and the second integrator lens  22  are configured by the fly-eye lenses composed of a plurality of lens cells disposed in a matrix array, and have functions to equalize the illumination distribution of the white light emitted from the light source lamp  19 . 
     The polarizing beam splitter (PBS)  23  includes a polarizing separation membrane and a phase retardation plate (½ wave plate). The polarizing separation membrane allows, from among the light from the second integrator lens  22 , for example, a P polarization to transmit, and an S polarization slightly to change the light path and emit. The P polarization light having transmitted the polarization separation membrane is converted into the S polarization by the phase retardation plate provided in the front side (light emitting side) thereof, and is emitted. That is, almost all the lights are aligned by the S polarization. 
     The light having passed through the polarizing beam splitter  23  passes through a condenser lens  24 , and reaches the first dichroic mirror  25 . The first dichroic mirror  25  reflects a blue component only of the light, and at the same time, has a function to allow red and green components to pass through, and the passing light of the red and green components reaches a second dichroic mirror  26 . The second dichroic mirror  26  reflects a green component of the light, and at the same time, has a function to allow the red component to pass through. Consequently, the white light emitted from the light source lamp  19  is divided into the blue light, the green light, and the red light by the first and second dichroic mirrors  25  and  26 . 
     The blue light reflected by the first dichroic mirror  25  is reflected by a total reflection mirror  27 , and the green light reflected by the second dichroic mirror  26  is as it is, and the red light having passed the second dichroic mirror  26  is reflected by total reflection mirrors  29  and  31  via relay lens  28  and  30 , and these are guided to an image generating optical system  32 , respectively. 
     The image generation optical system  32  is detachably disposed with a prism assembly part  35  (see  FIG. 4 ) fitted with a liquid crystal panel  34   r  for the red color, a liquid crystal panel  34   g  for the green color, a liquid crystal panel  34   b  for the blue color, and the like, respectively, at the three lateral sides of a cube-shaped color synthesis prism  33 . Between the color synthesis prism  33  and the liquid crystal panel  34   r  for the red color, an outgoing side polarizing plate  36   r  is disposed, and between the color synthesis prism  33  and the liquid crystal panel  34   g  for the green color, an outgoing side polarizing plate  36   g  and a fronting polarizing plate  37   g  are disposed, and between the color synthesis prism  33  and the liquid crystal panel  34   b  for the blue color, an outgoing side polarizing plate  36   b  and a fronting polarizing plate  37   b  are disposed. At the incident sides of three pieces of the liquid crystal panels  34   r ,  34   g , and  34   b , incident side polarizing plates  38   r ,  38   g , and  38   b , and condenser lenses  39   r ,  39   g , and  39   b  are disposed, respectively. 
     Consequently, the blue light reflected by the first dichroic mirror  25  and the total reflection mirror  27  is guided to the condenser lens  39   b  for the blue color, and reaches the color synthesis prism  33  by passing through the incident side polarizing plate  38   b , the liquid crystal panel  34   b  for the blue color and the fronting polarizing plate  37   b , and the outgoing side polarizing plate  36   b . The green light reflected by the second dichroic mirror  26  is guided to the condenser lens  39   g  for green color, and reaches the color synthesis prism  33  by passing through the incident side polarizing plate  38   g , the liquid crystal panel  34   g  for the green color and the fronting polarizing plate  37   g , and the outgoing side polarizing plate  36   g . Likewise, the red color light transmitting the first dichroic mirror  25  and the second dichroic mirror  26 , and reflected by two pieces of the total reflection mirrors  29  and  31 , is guided to the condenser lens  39   r  for the red color, and reaches the color synthesis prism  33  by passing through the incident side polarizing plate  38   r , the liquid crystal panel  34   r  for the red color and the outgoing side polarizing plate  36   r.    
     Three colors of image light guided by the color synthesis prism  33  is synthesized by this color synthesis prism  33 , and the color image light obtained by this synthesis passes through the projection lens  4 , thereby to be enlargedly projected onto a frontward screen. 
       FIGS. 8 to 11  are enlarged views of principal parts showing the light source lamp cooling mechanism in the present embodiment.  FIG. 8  is a perspective view of the front side seen obliquely from above, and  FIG. 9  is a perspective view of the back side seen obliquely from above in which an upper half of a duct is removed.  FIG. 10  is a perspective view in which a holder of the light source lamp in  FIG. 9  is removed, and  FIG. 11  is a cross-sectional view of the principal parts seen from the back side. 
     The light source lamp  19  of the present embodiment has an arc tube  191  composed of a high-pressure mercury lamp, the metal-halide lamp, and the like, and a reflector  192  disposed so as to cover this arc tube  19  and formed in the inner surface with a paraboloidal reflecting surface and opened in the front surface. This reflector  192 , as shown in  FIG. 10 , is formed with a suction port  193  and an exhaust port  194  opposed to each other on the front surface opening edge. 
     The light source lamp  19  thus configured is loaded on a lamp holder  195  made of aluminum as shown in  FIGS. 8 and 9 . This aluminum lamp holder  195  is configured to be provided with a heat-resisting glass plate  196  blocking a front surface opening of the reflector  192 , and at the same time, formed with a ventilation wire netting  197  composed of a large number of small holes corresponding to the suction port  193  and the exhaust port  194  of the reflector  192 , so that the fragment does not fly in all directions when the arc tube  191  is burst. 
     The conventional light source lamp cooling mechanism is disposed with the fan and the discharge portion in consideration of the cooling only of the light source lamp, and therefore, even when the cooling of the light source lamp is performed, by that much, the exhaust temperature increases. The projection type image display apparatus such as the liquid crystal projector has come to require a raised output of the light source lamp and the miniaturization of the apparatus all together, and in the conventional art as explained above, even if the cooling of the light source lamp of a high output can be performed, the exhaust temperature exceeds a permissible zone of the user and increases too much, thereby making it difficult to achieve both the cooling of the light source lamp and a reduction in the exhaust temperature. As its countermeasure, when the output (the number of rotations) of the fan is increased, the noise of the fan is increased. 
     Hence, the present embodiment includes, as a fan to cool the light source lamp  19 , the suction fan (first fan)  16  having the inner discharge port  161  sending the air through the suction port  193  formed in the reflector  192  inside the light source lamp  19  and the outer discharge ports  162  and  163  sending the air to the outer surfaces of the reflector  192 , and the exhaust fan (second fan)  17  exhausting an exhaust air around the light source lamp  19  to the outside through an exhaust hole  8  formed in the side wall of the housing  2 . The suction fan  16  is composed of the sirocco fan, and the exhaust fan  17  is composed of the axial fan. 
     The outer discharge ports  162  and  163  of the suction fan  16  are formed by deviating from the outer surface center portion of the reflector  192  of the light source lamp  19 , and at the same time, the exhaust fan  17  is disposed inclined such that its suction direction is directed toward the outer discharge ports  162  and  163  of the suction fan  16 . 
     Each of the discharge ports  161 ,  162 , and  163  circularly bends the distal end of the duct  164  to the light source lamp  19  side and is formed on its distal end, the duct  164  extending to the lateral side of the light source lamp  19  from the suction fan  16  disposed at the lateral side in the irradiation direction of the light source lamp  19 . An inner discharge port  161  is formed by corresponding to a suction port  193  formed in the reflector  192  of the light source lam  19 , while the outer discharge ports  162  and  163  are formed above and below two pieces by deviating vertically from the outside surface center portion of the reflector  192  of the light source lamp  19 . 
     As explained above, the degree of deviating the outer discharge ports  162  and  163  of the suction fan  16  from the outside surface center portion and the degree of inclining the exhaust fan  17  such that its suction direction is directed to the outer discharge ports  162  and  163  of the suction fan  19  are set in consideration of the cooling of the light source lamp  19  and the exhaust temperature. 
     By being thus configured, the interior of the light source lamp  19  having the arc tube  191  reaching the highest temperature can be effectively cooled by using the inner discharge port  161  of the suction fan  16 . The outer surface (including a neck portion  198  projected from its back end) of the reflector  192  of the light source lamp  19 , which does not reach the temperature high enough as the interior of the light source lamp  19 , can be suitably cooled by using the outer discharge ports  162  and  163  of the suction fan  16  formed by deviating from the outer surface center portion. 
     Since the exhaust fan  17  is disposed inclined such that its suction direction is directed to the outer discharge ports  162  and  163  of the suction fan  16 , the air from the outer discharge ports  162  and  163  of the suction fan  16  formed by deviating from the outer surface center portion of the light source lamp  19  cools the outer surface of the light source lamp  19 , and at the same time, a part of the air is directly sucked into the exhaust fan  17 , and is mixed with the exhaust air increased in temperature by having cooled the interior of the light source lamp  19 , and is exhausted to the outside, thereby reducing the exhaust temperature. 
     Consequently, without increasing the outputs of the suction fan  16  and the exhaust fan  17  so much, the cooling of the light source lamp  19  and the reduction in the exhaust temperature can be both achieved, so that the noise can be also suppressed low. 
     Further, by forming the outer discharge ports  162  and  163  of the suction fan  16  above and below two pieces by deviating from the outer surface center portion of the light source lamp  19 , the outer surface of the light source lamp  19  can be approximately equally cooled. 
     The degree of deviating each of the discharge ports  161  and  162  of the suction fan  16  from the outer surface center portion of the light source lamp  19  and the degree of inclining the exhaust fan  17  such that its suction direction is directed toward the outer discharge ports  162  and  163  of the suction fan  16  are set in consideration of the cooling of the light source lamp  19  and the exhaust temperature, and therefore, the cooling of the light source lamp  19  and the reduction in exhaust temperature can be both flexibly achieved in conformity with the raised output of the light source lamp  19 , the miniaturization of the apparatus, and the like. 
     Further, each of the discharge ports  161 ,  162 , and  163  of the suction fan  16  is formed in the duct  164  extended from the suction fan  16  to the light source lamp  19 , so that a degree of freedom of the positioning of the suction fan  16  is improved. 
     Thus, according to the present embodiment, since the light source lamp cooling mechanism as explained above is provided, so that, without increasing the outputs of the fans  16  and  17  so much, the liquid crystal projector  1  capable of achieving the cooling of the light source lamp  19  and the reduction of the exhaust temperature as well as reducing the noise can be realized. 
       FIGS. 12 to 15  are enlarged views of the principal parts showing an optical part cooling mechanism in the present embodiment.  FIG. 12  is a perspective view seen obliquely from above from the front side,  FIG. 13  is a top plan view,  FIG. 14  is a top plan view in which optical parts such as the liquid crystal panels and the like are removed, and  FIG. 15  is a back view in which the lower half of the duct is removed. 
     As explained earlier, heretofore, there has been known a device cooling three pieces of liquid crystal panels corresponding to a red light, a green light, and a blue light and polarizing plates disposed at the incident side and the outgoing side of each liquid crystal panel by one set of the fan every color, that is, by a total of three sets of the fans. 
     Meantime, three pieces of the liquid crystal panels corresponding to the red light, the green light, and the blue light, and the polarizing plates and the like disposed at the incident side and the outgoing side of each liquid crystal panel are different in temperature rise and degree of ultraviolet deterioration every color, and therefore, the required cooling amount is also different. Particularly, since the blue light is close to the ultraviolet region, to avoid the ultraviolet deterioration, the required amount of cooling becomes large. 
     The projection type image display apparatus such as a liquid crystal projector and the like has come to require the enhancement of luminance by the raised output of the light source lamp, the miniaturization of the apparatus, and a reduced cost (miniaturization of the liquid crystal panel and the like) all together, and the amount of light per unit area of high luminance has come to be increased. 
     However, the conventional art that performs cooling by one set of the fan for each color has been unable to cope with the model whose amount of light per unit of high luminance has come to be increased. As a countermeasure, when the output of the fan (the number of rotations) is increased, the noise of the fan is increased. Further, the cooling of the PBS needs to be also performed. 
     Hence, in the present embodiment, the incident side and the outgoing side of each of the liquid crystal panels  34   r ,  34   g , and  34   b  are formed with discharge ports r 1  and r 2 , g 1  and g 2 , and b 1  and b 2  to discharge the air from three sets of suction fans  41 ,  42 , and  43  through ducts  411 ,  421 , and  431 . At the same time, the PBS  23  is formed with a discharge port p 1  to discharge the air from the suction fan  43  through the duct  432 . An incident side discharge port b 1  and an outgoing side discharge port p 2  of the liquid crystal panel  34   b  corresponding to the blue color are formed with a duct so as to discharge the air from the suction fans  43  and  41  which are different from each other. Incidentally, each of the suction fans  41  to  43  is composed of the sirocco fan. 
     That is, the duct is configured such that, by one set of the suction fan  43 , the air is sent to the incident side discharge port b 1  of the liquid crystal panel  34   b  corresponding to the blue light and the discharge port p 1  of the PBS  23 , and by the other two sets of the suction fans  41  and  42 , the air is sent to the incident side discharge ports r 1  and g 1  of each of the liquid crystal panels  34   r  and  34   g , to the outgoing side discharge port r 2  and g 2  corresponding to the red light and the green light, and to the outgoing side discharge port b 2  of the liquid crystal panel  34   b  corresponding to the blue light. 
     To explain more specifically, the duct is configured such that, by one set of the suction fan  42  from among two sets of the suction fans  41  and  42 , the air is sent to the incident side discharge port g 1  and to the outgoing side discharge port g 2  of the liquid crystal panel  34   g  corresponding to the green light through the duct  421 , and by the other set of the suction fan  41 , the air is sent to the incident side discharge port r 1  and to the outgoing side discharge port r 2  of the liquid crystal panel  34   r  corresponding to the red light and the outgoing side discharge port b 2  of the liquid crystal panel  34   b  corresponding to the blue light by extending the duct  411 . 
     By being thus configured, by three sets of the suction fans  41  to  43 , the incident side and the outgoing side of each of the liquid crystal panels  34   r ,  34   g , and  34   b  in addition to the PBS  23  can be cooled. The incident side and the outgoing side of the blue light which is large in required cooling amount can be sufficiently cooled by using the suction fans  43  and  41  which are different from each other. Consequently, even when the amount of light per unit area of high luminance is increased, without increasing the output (the number of rotations) of the suction fans  41  to  43  so much, the liquid crystal panels  34   r ,  34   g , and  34   b , and the polarizing plates  36   r ,  36   g ,  36   b ,  37   g ,  37   b ,  38   r ,  38   g , and  38   b , and the PBS  23  can be cooled by three sets of the suction fans  41  to  43 , thereby reducing the noise also. 
     Further, the duct is configured such that, by one set of the suction fan  43 , the air is sent to the incident side discharge portion b 1  of the liquid crystal panel  34   b  corresponding to the blue light and to the discharge port p 1  of the PBS  23 , and by the other two sets of the suction fans  41  and  42 , the air is sent to the incident side discharge ports r 1  and g 1 , to the outgoing side discharge ports r 2  and g 2  of each of the liquid crystal panels  34   r  and  34   g  corresponding to the red light and green light, and to the outgoing side discharge port b 2  of the liquid crystal panel  34   b  corresponding to the blue light, so that, in the system disposed with the liquid crystal panel  34   b  of the blue light at the PBS  23  side similarly to the optical system  13  of the present embodiment, by the shortest duct configuration, the above explained effect can be realized. Further, by the suction fan  41  for red light that increases least in temperature, the air can be sent to the outgoing side discharge port b 2  of the liquid crystal panel  34   b  corresponding to the blue light. Incidentally, if the suction fan for the green light that increases most in temperature is not enough with one set of the suction fan  42 , the air may be sent from the suction fan  41  for red light. 
     Similarly to the present embodiment, the duct is configured such that, by one set of the suction fan  42  from among the two sets of suction fans  41  and  42 , the air is sent to the incident side discharge port g 1  and to the outgoing side discharge port g 2  of the liquid crystal panel  34   g  corresponding to the green light, and by another one set of the suction fan  41 , the air is sent to the incident side discharge port r 1 , to the outgoing side discharge port r 2  of the liquid crystal panel  34   r  corresponding to the red light, and to the outgoing side discharge port b 2  of the liquid crystal panel  34   b  corresponding to the blue light, so that the above explained effect can be realized without the duct configuration becoming complicated. 
     Thus, according to the present embodiment, since the apparatus is provided with the optical part cooling mechanism as explained above, even when the amount of light per unit area of high luminance is increased, without increasing the output (the number of rotations) of the fan so much, the liquid crystal panel and the polarizing plate as well as the PBS can be cooled by three sets of the fans, so that the liquid crystal projector  1  capable of reducing the noise can be realized. 
     Next, the power source unit of the present embodiment will be explained. 
     Heretofore, it has been common to mount a noise removal filter portion on the circuit substrate of the power source unit. 
     As explained above, the projection type image display apparatus such as a liquid crystal projector and the like has come to require the enhancement of luminance by the raised output of the light source lamp, the miniaturization of the apparatus, and a reduced cost all together, and because of the raised output of the light source lamp, the power source unit has also come to require a large output. 
     However, in the case of the model having a small output, even when the noise removal filter is mounted on the circuit substrate of the power source unit similarly to the conventional art, this does not cause a problem. However, when the output becomes large, a noise removal filter portion having a core (coil) incapable of being miniaturized becomes large, thereby upsizing the power source unit. 
     When the power source unit becomes large, the fan that cools this power source unit also becomes large, and the output (the number of rotations) is required to be increased. This results in lowering of the cooling performance and making the noise large. As its countermeasure, though it is conceivable to separate the noise removal filter portion and make it into a separate type, a noise is liable to enter the connecting line, and because of the increased use of the core, the EMC (ElectroMagnetic Compatibility) measure becomes formidable thereby inviting a high cost. 
     Hence, in the present embodiment, as explained above, the noise removal filter portion  15  is separated from the power source unit main body  14 , and at the same time, the separated noise removal filter portion  15  is disposed to be positioned as closely as possible to the housing back side wall provided with the power source inlet  10  and the power unit main body  14 , respectively. 
     Specifically, along the front side wall of the horizontally long house  2 , the power source unit main body  14  is disposed, and at the position opposed to the power source unit main body  14  in the back side wall, the noise removal filter portion  15  is disposed along the back side wall. 
     By being thus configured, even when the output of the light source lamp  19  becomes large, the power source unit main body  14  can be miniaturized, so that a reduction in the noise can be made possible by the improvement of the cooling performance. In addition, the connecting line is minimized, so that a reduction in the cost is made possible by making the EMC measure (reduction in the use of the core and the like) more effective. 
     Further, by disposing the noise removal filter portion  15  close to the housing back side wall provided with the power source inlet  10 , a power source cord is not brought to the lateral side of the housing  2 , so that the above explained effect can be obtained with the usability of the lateral side of the housing  2  not harmed. 
     Further, the power source unit main body  14  is disposed along the front side wall of the horizontally long house  2 , and by disposing the noise removal filter portion  15  at the position opposed to the power source unit main body  14  in the back side wall, even when the noise removal filter portion  15  is disposed along the back side wall, the connecting line can be made shortest, so that the above explained effect can be obtained without making the disposal configuration of each part inside the housing  2  complicated. 
     Thus, according to the present embodiment, the power source unit as explained above is provided, so that even when the output of the light source lamp  19  becomes large, the liquid crystal projector  1  capable of reducing the cost by a reduction of the noise by improving the cooling performance and making the EMC measure more effective can be realized. 
     Incidentally, in the present embodiment, since the housing  2  is horizontally long, even when the power source unit main body  14  and the noise removal filter portion  15  are arranged in parallel along the front side wall and the back side wall, respectively, the connecting line can be made shortest, while in the case of the housing vertically long front to back, the disposition as explained above is unable to make the connecting line shortest, and therefore, in this case, for example, if the noise removal filter is disposed front and back, then, it is possible to dispose the noise removal filter portion close to the housing back side wall and the power source unit main body, respectively. 
     Next, the exhaust mechanism in the present embodiment will be explained. 
     Heretofore, there has been known the exhaust mechanism placed with two sets of exhaust fans side by side close to the light source lamp, the exhaust fans exhausting the exhaust air to the outside from the light source lamp, the power source unit, and the like. 
     As explained above, while the projection type image display apparatus such as the liquid crystal projector has come to require the raised output of the light source lamp and the miniaturization of the apparatus all together. The exhaust air of high temperature from the high output light source lamp is exhausted, but a reduction in the exhaust temperature and a reduction in the noise of the exhaust fan have become a key issue. 
     However, to achieve a reduction in noise of the side by side exhaust fans installed by the conventional art as explained above, a space needs to be left between the fan and the housing side wall, and this hinders the miniaturization. To reduce the temperature of the exhaust air, it is conceivable to dispose each of the exhaust fans installed side by side so as to be inclined in a V shape in the mutual exhausting direction so that the exhaust air of high temperature from the light source lamp and the exhaust air of the relatively low temperature from the power source unit and the like are mixed, but even in this case also, a space therefore is required, and the miniaturization is thus hindered. 
     Hence, in the present embodiment, as shown in  FIGS. 3 ,  4 , and the like, the first exhaust fan  17  which mainly exhausts the exhaust air from the light source lamp  19  (light source lamp unit  12 ) to the outside and the second exhaust fan  18  which mainly exhausts the exhaust air from the power source unit main body  14  to the outside are horizontally installed side by side, and at the same time, the second exhaust fan  18  side end portion in the first exhaust fan  17  is moved inward, and the first exhaust fan  17  is disposed inclined such that its exhaust direction is directed to the exhaust side of the second exhaust fan  18 . 
     The first exhaust fan  17  is disposed inclined to a large number of slit-like exhaust holes  8  formed in the housing side wall, and moreover, is disposed inclined such that the exhaust air from the exhaust holes  8  are exhausted inclined obliquely forward. 
     The first exhaust fan  17  and the second exhaust fan  18 , as shown in  FIGS. 16 and 17 , are fixed to a frame body  50  in advance and unitized so as to take on the above explained disposal configuration, and when this exhaust fan unit  51  is fitted to the predetermined position of the lower case  2   b  of the housing  2 , the above explained disposal configuration can be easily realized. Incidentally, since the first exhaust fan  17  sucks down the exhaust air of high temperature from the light source lamp  19 , as shown in  FIG. 17 , the back side is configured to be covered by a cover  52  with the center motor portion blocked and protect the motor portion from the exhaust air of high temperature from the light source lamp  19 . 
     By being thus configured, the first exhaust fan  17  is inclined inward, so that the miniaturization is not hindered, and further, a space can be formed between the housing side wall and the first exhaust fan  17 , thereby reducing the noise to a lower level. Further, the exhaust air of high temperature from the light source lamp  19  and the exhaust air of the relative low temperature from the power source unit main body  14  are mixed, thereby reducing the temperature of the exhaust air. 
     Since the light source lamp is brought to a high temperature, and is disposed spaced further apart from the exhaust fan than before, the above explained configuration and effect can be easily realized. 
     Further, since the second exhaust fan  18  exhausts the exhaust air mainly from the power source unit main body  14  to the outside, it can also simultaneously exhaust the exhaust air of the important power source unit main body  14 , though not higher in temperature than the light source lamp  19 . 
     Further, the first exhaust fan  17  which exhausts the exhaust air from the light source lamp  19  to the outside is disposed inclined to a large number of slit-like exhaust holes  8  formed in the housing side wall, so that the air in high temperature from the light source lamp  19  is exhausted obliquely from a large number of slit-like exhaust holes  8 , and by that much, the exhaust air becomes hard to be exhausted, thereby to be easily mixed with the exhaust air of the relatively low temperature from the second exhaust fan  18  with a result that the exhaust air temperature can be reduced much more than before. 
     Further, the first exhaust fan  17  which exhausts the exhaust air from the light source lamp  19  is disposed inclined so as to exhaust obliquely frontward the exhaust air from the exhaust holes  8  formed in the housing side wall, so that the exhaust air of high temperature can be prevented from being laterally blown out to an operator and the like. 
     Thus, according to the present embodiment, since the exhaust mechanism as explained above is provided, the liquid crystal projector  1  capable of reducing the noises of the exhaust fans  17  and  18  and lowing the exhaust temperature, while achieving down-sizing can be realized. 
     Incidentally, in the present embodiment, though the first exhaust fan  17  has been inclined, if an extra room available inside space-wise, even when the second exhaust fan  18  is conversely inclined similarly to the first exhaust fan, a fixed effect can be expected.