Abstract:
A projection type display apparatus includes a housing having a first side having an air intake opening and a second side having an air exhaust opening, a light source for supplying light, and a light valve device which modulates the light output from the light source. A centrifugal fan is associated with the air intake opening so as to draw air from the air intake opening. A first ventilation path is coupled with the air intake opening so as to lead air flow from the air intake opening toward a lower portion of the light valve, and a second ventilation path is formed from the lower portion of the light valve to an upper portion of the light valve. An exhaust fan is associated with the air exhaust opening so as to draw out air flowing from the second ventilation path through the air exhaust opening.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a continuation of U.S. application Ser. No. 11/055,482, filed Feb. 11, 2005, now U.S. Pat. No. 7,021,768, which is a continuation of U.S. application Ser. No. 10/109,663, filed Apr. 1, 2002, now U.S. Pat. No. 6,857,749 which is a continuation of U.S. application Ser. No. 09/911,806, filed Jul. 25, 2001, now U.S. Pat. No. 6,431,710, which is a continuation of U.S. application Ser. No. 09/347,454, filed Jul. 6, 1999, now U.S. Pat. No. 6,280,038, the subject matter of which is incorporated by reference herein. 

   BACKGROUND OF THE INVENTION 
   The present invention relates to optical equipment, such as a liquid crystal projector. Especially, the invention is concerned with optical equipment that has a suitable cooling system to cool a light valve arrangement in the optical equipment. 
   A conventional optical apparatus having a light valve arrangement, as described in Japanese patent Laid-open Publication 8-179424, employs an axial-flow type ventilation device located under the light valve arrangement as a ventilation system so as to prevent the light valve arrangement from reaching a high temperature. In this case, because the flow of air from the ventilation system can be applied to the light valve arrangement directly, the light valve arrangement can be cooled. 
   Because a ventilation system is provided below the light valve arrangement in the conventional optical equipment, the air is supplied from the base side of the equipment to the ventilation system. Thus, it was necessary to provide a space on the base side of the equipment to reduce the flow resistance of the air that is drawn in from the equipment side. Further, because the height of the optical equipment becomes equal to the height of the ventilation system and a rectifier added to the height of the projection lens or the light valve arrangement, it was difficult to make the equipment thin. 
   Further, such space was hard to provide in practical use underneath the projection lens (dead space) for this ventilation system, so that it was arranged at a position where it projected from underneath the projection lens, with a result that it wasn&#39;t possible to reduce the size of the whole device or effect a reduction of the height measurement. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide optical equipment having a discharge lamp for supplying light, and a light valve device for projecting said light, comprising: 
   a case for housing said optical equipment; 
   an air intake opening arranged on the side of said case; 
   a ventilation device adapted to draw in air through said air intake opening; and 
   a ventilation path arranged between said ventilation device and said light valve device, wherein 
   said ventilation path is divided into a plurality of air flow paths so as to cool said light valve device by ventilated air from said ventilation device. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a diagrammatic plan view of one of the embodiments of the optical equipment according to the present invention. 
       FIG. 2  is a perspective view that shows an example of a ventilation path. 
       FIG. 3  is a perspective view that shows an example of cooling structure using the ventilation path that is illustrated in  FIG. 2 . 
       FIG. 4  is a perspective view that shows an embodiment of the optical equipment according to the present invention. 
       FIG. 5  is a perspective view that shows another embodiment of the optical equipment according to the present invention. 
       FIG. 6  is a sectional view that shows another example of the cooling structure that is used for optical equipment according to the present invention. 
       FIG. 7  is a sectional view that shows another embodiment of the cooling structure that is used for optical equipment according to the present invention. 
       FIG. 8  is a diagrammatic plan view of still another embodiment of the optical equipment according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A first embodiment of the present invention will be explained with reference to  FIG. 1 . 
   In  FIG. 1 , a light beam  2  from a discharge lamp  1 , that is used as a light source, is directed to a polarizing conversion element  6  by means of a lamp reflector  3  in the form of a parabolic face mirror reflector, through a lens  4  and a lens  5 . The light beam  2  is illuminated on a first dichroic mirror  10  through first lens array  7 , mirror  8 , and second lens array  9 . 
   A red color light component  11  is passed by mirror  10 , and light beam  12 , including a green color light component and a blue color light component, is reflected by the first dichroic mirror  10 . The red color light component  11  is reflected by a first mirror  13  onto a first light valve  14  through a first polarization plate  81 . The green color light component included in the light beam  12  is reflected by a second dichroic mirror  15  onto a second light valve  18  through a second polarization plate  82 . The remaining blue color light component  17  included in the light beam  12  passes through the second dichroic mirror  15  and is illuminated on a third light valve  21  through a second mirror  19 , a third mirror  20  and a third polarization plate  83 . 
   A portion of the red light component passing through the first light valve  14 , a portion of the green light component passing through the second light valve  18 , and a portion of the blue light component passing through the third light valve  21  are combined by a cross dichroic prism  25 . The combined outgoing light  26  from the cross dichroic prism  25  is projected on a screen (not shown) by a projection lens  27 . 
   In this embodiment, a color separation optical system is formed by the first dichroic mirror  10 , the second dichroic mirror  15 , the first mirror  13 , the second mirror  19 , and the third mirror  20 , and the color separation optical system is arranged around the cross dichroic prism  25 . Further, the illumination optical system is designed to improve the utilization efficiency of the illumination light from the light source and to obtain uniform illumination light. The illumination optical system is formed by the discharge lamp  1  operating as a light source, the lamp reflector  3 , the lens  4 , the lens  5 , the polarizing conversion element  6 , the first lens array  7  that forms a optical integrator, the mirror  8 , and the second lens array  9 . In addition, there is a lamp power supply  31  that provides power for the light source. In this embodiment, the projection lens  27 , the cross dichroic prism  25 , the color separation optical system, the illumination optical system and the lamp power supply  31  are arranged from an upper part to a lower part in  FIG. 1  in this order. 
   Further, optical parts of the color separation optical system and the illumination optical system are held within an optical case  200 . In addition, the optical equipment includes a case  29 , which is provided with a first air intake opening  91 , a second air intake opening  92 , and an air exhaust opening  93 . A ventilation unit  61  is provided for cooling the first light valve  14 , the second light valve  18 , and the third light valve  21 , respectively. A centrifugal fan is utilized as the ventilation unit  61  in this embodiment. Numeral  65  denotes a ventilation path to lead a cool air flow toward the lower portion of the optical case  200 , and numeral  67  denotes a ventilation path for intake air flow. Numeral  95  denotes a duct to lead intake air to the ventilation unit  61 . 
   In  FIG. 1 , the air flow taken in from the air intake opening  91 , flows as shown by arrows W 1  to W 5  in the case  29  from operation of a fan for intake of air  63 . Air is drawn into the ventilation path  67  from the intake side of the ventilation unit  61 . The air flow that is used for cooling the first light valve  14 , the second light valve  18 , and the third light  21  passes along the ventilation path  65  from the exhaust side of the ventilation unit  61 , comes out into the upper part of the case  29  and is discharged in the case  29 . 
   Further, in this embodiment, as above-mentioned, the case  29  is provided with a second air intake opening  92 . The intake air is drawn in by the fan  62  and flow through the first lens array  7 , the polarizing conversion element  6 , lens  5 , and the lamp power supply  31  and cools them. 
   In addition, the heat that is generated from the light source that reaches a high temperature does not exert an influence on the structural parts other than the light source itself. An exhaust fan  28  used for cooling the light source is arranged beside the discharge lamp  1  and the lamp reflector  3  so as not to influence structural parts other than the light source by the high temperature that is generated by the light source, and a high velocity air flow  30  is exhausted to the outside of the case  29  of the projector through the exhaust opening  93 . The lamp power supply  31  is arranged beside the discharge lamp  1 . Simultaneously, the exhaust fan  28  draws out air from the case  29  for cooling the first light valve  14 , the second light valve  18  and the third light valve  21 . 
   In the following, details of the cooling provided in accordance with present invention will be explained with reference to  FIG. 2  and  FIG. 3 . In  FIG. 2  and  FIG. 3  the ventilation unit  61  is arranged at the opposite side of the position shown in  FIG. 1 . Accordingly, a cooling structure is shown in which the ventilation unit  61  is on the right side of the projection lens  27  as you face it. However, it is possible for the ventilation unit  61  to be arranged on the left side of projection lens  27  as you face it. 
     FIG. 2  is a perspective view that shows an example of the ventilation path.  FIG. 3  is a perspective view that shows an example of the cooling structure using the ventilation path that is indicated in  FIG. 2 . The perspective views of  FIG. 2  and  FIG. 3  represents a view as seen from the X direction of  FIG. 1 . 
   As shown in  FIG. 2 , a first guide member  123 , a second guide member  124 , a third guide member  125 , and a fourth guide member  126  are arranged such that a cooling air flow is divided into a first air flow path  101  and a second air flow path  102  by the first guide member  123 . Consequently, the cooling air is divided into a first air flow, which passes through the first air flow path  101  to cool the second light valve  18 , and a second air flow which passes through the second air flow path  102  to cool the first light valve  14 . Next, the second air flow path  102  is divided into a third air flow path  103  and a fourth air flow path  104  by the second guide member  124 . Consequently, the cooling air is divided into a third air flow and a fourth air flow. The third air flow passes through the third air flow path  103  to cool the first light valve  14 . The fourth air flow passes through the fourth air flow path  104  to cool the third light valve  21 . 
   Further, the first air flow path  101  is divided into a fifth air flow path  105  and a sixth air flow path  106  by the fourth guide member  126 . Consequently, the cooling air is divided into a fifth air flow and a sixth air flow. The fifth air flow passes through the fifth air flow path  105  and flows to the incoming light side of the second light valve  18  to cool the incoming light side of the second light valve  18 . The sixth air flow passes through the fifth air flow path  106  and flows to the outgoing light side of the second light valve  18  to cool the outgoing light side of the second light valve  18 . 
   Further, the second air flow path  102  is divided into a seventh air flow path  107  and an eighth air flow path  108  by the second guide member  124 . Consequently, the cooling air is divided into a seventh air flow and an eighth air flow. The seventh air flow passes through the seventh air flow path  107  and flows to the incoming light side of the first light valve  14  to cool the incoming light side of the first light valve  14 . The eighth air flow passes through the eighth air flow path  108  and flows to the outgoing light side of the first light valve  14  to cool the outgoing light side of the first light valve  14 . 
   Further, the fourth air flow path  104  is divided into a ninth air flow path  109  and a tenth air flow path  110  by the third guide member  125 . Consequently, the cooling air is divided into a ninth air flow and a tenth air flow. The ninth air flow passes through the ninth air flow path  109  and flows to the incoming light side of the third light valve  21  to cool the incoming light side of the third light valve  21 . The tenth air flow passes through the tenth air flow path  110  and flows to the outgoing light side of the third light valve  21  to cool the outgoing light side of the third light valve  21 . 
   Next, the cooling structure for cooling the light valves will be explained in detail with reference to  FIG. 3 . As shown in  FIG. 3 , the fifth air flow, that is one of the air flows for cooling with air flowing from the ventilation path  65 , is ventilated to the incoming light side of the second light valve  18 . Accordingly, the fifth air flow is ventilated to the side of the second incoming light side polarizing plate  82  and is used for cooling both the incoming light side of the second light valve  18  and the second incoming light side polarizing plate  82 . 
   Further, the seventh air flow, that is ventilated from the ventilation path  65 , flows to the incoming light side of the first light valve  14 . Accordingly, the seventh air flow is ventilated to the side of the first incoming light side polarizing plate  81  and is used for cooling both the incoming light side of the first light valve  14  and the first incoming light side polarizing plate  81 . The eighth air flow is ventilated to the outgoing light side of the first light valve  14  and cools both the outgoing light side of the first light valve  14  and the incoming light side of the cross-dichroic prism  25 . 
   Further, the ninth air flow, that is ventilated from the ventilation path  65 , flows to the incoming light side of the third light valve  21 . Accordingly, the ninth air flow is ventilated to the side of the third incoming light side polarizing plate  83  and is used for cooling both the incoming light side of the third light valve  21  and the third incoming light side polarizing plate  83 . The tenth air flow ventilated from the ventilation path  65  flows to the outgoing light side of the third valve  21  and the incoming light side of the cross dichroic prism  25 . 
   One example of the structure that is used for cooling the first light valve  14 , the second light valve  18  and the third light valve  21  has been described. However, the air volume and air velocity can be easily adjusted for each of the first to tenth air flows, if the position and the shape of each of the first to fourth guide members  123 ,  124 ,  125 , and  126  is arranged properly. For instance, in the case where the calorific value of the outgoing light side of the second light valve  18  and the outgoing light side of the first light valve  14  is large, each guide member, such as guide members  123 ,  124 ,  125 , may be arranged so as to carry a maximum amount of the ventilation volume and air velocity of the sixth air flow for cooling the second light valve  18  and the eighth air flow for cooling the first light valve  14 . 
   Further, in the case where the calorific value of the third light valve is not large, the ventilation of the ninth air flow and the tenth air flow is throttled by the guide members. Therefore, the value of the increasing temperature can be substantially equalized. Further, it is easy to control the value of the increasing temperature on the incoming light side of each the first to third incoming light side polarizing plates  81 ,  82 , and  83 , if the velocity of each of the fifth, seventh and ninth air flows is adjusted by the second to fourth guide members  124 ,  125 , and  126 . As a result, the air velocity produced by ventilation unit  61  can be used very efficiently. 
   As shown in  FIG. 2  and  FIG. 3 , in accordance with this invention, since the ventilation path is formed by a plurality of divided flow paths, each of the first to the third light valves  14 ,  18 , and  21  has their own flow path such as flow paths  101 ,  102 ,  103 , and  104 . Therefore, the present invention is effective for achieving miniaturization and a thin type of optical equipment. Further, the present invention can provide optical equipment that has a cooling system which operates with a high efficiency to cool a light valve arrangement having a large calorific value. 
   In addition, the present invention, which uses a centrifugal fan as the ventilation unit  61 , provides divided flow paths to obtain a smooth flow of the cooling air so as to reduce the pressure loss of the air flow to the incoming and outgoing light side of each light valve. Accordingly, a sufficient volume of air can be achieved. Further, the present invention can provide an efficient cooling system and cut down on the height of the optical equipment. The present invention can supply cooling air from the ventilation unit  61  to each the first to third light valves  14 ,  18 , and  21  so as to equalize the increase in temperature of each of the first to third light valves  14 ,  18 , and  21 . Therefore, the present invention can adequately decrease the temperature of each of the first to the third light valves  14 ,  18 , and  21 . 
   The present invention provides optical equipment having an efficient cooling system that can control the air volume and air flow velocity freely. The present invention can adjust the air volume and air flow velocity to the second light valve  18  and the third light valve  21  so that their light absorption factors become large, and control the air volume and air flow velocity to the first light valve  14  so that its light absorption factor becomes small. Therefore, the present invention can adjust the air flow that passes through the flow path and provide optical equipment with an efficient cooling system. Further, the present invention can control the incoming and outgoing right side of the first to third valves  14 ,  18 , and  21  so as to reduce the temperature of each the first to the third light valves  14 ,  18 , and  21  to within a permissive range. 
   In the above-described embodiment, the air flow from the ventilation unit  61  is divided by the first to fourth guide members  123 ,  124 ,  125 , and  126 . A similar effect can be obtained if the structure is divided by different pipes having a plurality of cross sections. In this embodiment, because the first air intake opening  91  is arranged on the end of the case  29  and the exhaust opening  93  is arranged on the side of the case  29 , the height of the optical equipment is reduced. Further, because an exhaust fan  28  is arranged beside the discharge lamp  1 , the exhaust fan  28  cools the discharge lamp  1  easily. 
   Next, the position of the ventilation unit in the optical equipment according to the present invention, are shown in  FIG. 4  and  FIG. 5 , will be described.  FIG. 4  is a perspective view that shows an embodiment of the optical equipment according to the present invention.  FIG. 5  is a perspective view that shows still another embodiment of the optical equipment according to the present invention. In  FIG. 4  and  FIG. 5 , each element that has the same function as described with reference to  FIG. 1  to  FIG. 3  is identified by the same number.  FIG. 4  and  FIG. 5  are perspective views as seen from the bottom of the equipment. 
   In the above-mentioned embodiment shown in  FIG. 1 , the ventilation unit  61  is stationed on the left side of the projection lens  27 . The ventilation unit  61  is positioned in this embodiment at an angle of 90 degrees relative to the ventilation unit  61  in  FIG. 1 . The ventilation unit  61  in  FIG. 4  is positioned on the opposite side as compared to the ventilation unit  61  in  FIG. 5 . 
   The ventilation unit  61  shown in  FIG. 4  and  FIG. 5  can produce substantially the same effect as that of the above-mentioned embodiment. Accordingly, the air intake direction of the ventilation unit  61  is arranged at the side of the case  29 , especially the upper side of the case  29  shown in  FIG. 1 , and so the intake of the air can be accomplished with little air flow resistance so as not to require space for an air flow path on the bottom side of the optical equipment. The same effect is provided furthermore whether the ventilation means is on the right or left of the projection lens  27 , as shown in  FIG. 4  and  FIG. 5 . When ventilation path  65  is located on the right or the left, such as for the optics unit  200  shown in  FIG. 4  or  FIG. 5 , it is possible to provide a constitution that ventilates the first to the third light valves  14 ,  18 ,  21 . 
     FIG. 6  is the sectional view that shows another example of the cooling arrangement that is used for optical equipment according to the present invention. 
   The cooling system according to the present invention can be applied in addition to the three light valves  14 ,  18 ,  21  individually. That is, it is possible also to adapt it to cool a light valve by applying a large amount of air to the center part of large calorific value of a large-sized sheet  210  of a light valve as shown in  FIG. 6  to decrease the circumference. 
   In  FIG. 6 , the air flow through the ventilation path  65  from the ventilation in unit  61  is divided and flows to the center of the light valve  210  as a first air flow (arrow  101 A), and to the peripheral part of the light valve  210  as a second air flow (arrow  102 A) and a third air flow (arrow  103 A) so as to cool the large light valve  210 . In this case, because the intake of the air by the ventilation unit  61  is produced from the side of the case  29 , the optical equipment can reduce the intake air flow resistance, which is advantageous in thin type optical equipment. 
   In the foregoing embodiment, the ventilation unit  61  is utilized as a means to direct an air flow toward the light valve, however, the following embodiment provides a ventilation unit  61  which draws in air to cause an air flow through the light valve.  FIG. 7  is the sectional view that shows another embodiment of the cooling structure that is used for optical equipment according to the present invention. 
   In  FIG. 7 , the ventilation unit  61  is positioned with the light valves on the exhaust side thereof, and the ventilation unit  61  causes air for cooling to be drawn in through the first to third light valves  14 ,  18 ,  21 . After the air, which flows through the ventilation path  65  and the second air flow path  103 , cools the first light valve  14 , the air is exhausted through the ventilation unit  61 . After the air, which flows through the first air flow path  101 , cools the second light valve  18 , the air is exhausted through the ventilation unit  61 . Also, after the air, which flows through the fourth air flow path  104 , cools the third light valve  21 , the air is exhausted by the ventilation unit  61  to the outside of the case  29 . 
   In the foregoing embodiment, the structure is such that the depth of the light projector is larger than the width of the light projector. However, the present invention is not limited to that. In other words, the width of the light projector may be larger than the depth of the projector. 
     FIG. 8  is a plan view that shows a still further embodiment of the optical equipment according to the present invention. In  FIG. 8 , the light  2 , from the discharge lamp  1  that is used as a light source is directed to a polarizing conversion element  6  by a lamp reflector  3  in the form of a parabolic mirror reflector, via a lens  4  and lens  5 , and then is directed to a dichroic mirror  40  through a first lens array  7 , a mirror  8 , and a second lens array  9 . The dichroic mirror  40  reflects a red color light component  41  and passes the remaining light beam  42 , including a green color light component and a blue color light component. The red color light component  41  is reflected by the mirror  13  and directed to a first light valve  14 . The green color light component  16  included in the light beam  42  is reflected by the second dichroic mirror  15  and is directed to the second light valve  18 . The blue color light component  17  included in the light beam  42  is passed by the second dichroic mirror  15 , and the blue color light component  17  is directed to the third light valve  21  through the second mirror  19  and the third mirror  20 . 
   A portion of the red light component supplied from the first light valve  14 , a portion of the green light component supplied from the second light valve  18 , and a portion of the blue light component supplied from the third light valve  21  are combined by a cross dichroic prism  25 . The combined outgoing light beam  26  from the cross-dichroic prism  25  is projected on a screen (not shown) by a projection lens  27 . In this embodiment, the outgoing light from the discharge lamp  1  is bent to a U-shape and projected on the screen (not shown). 
   The heat that is generated from the light source and produces a high temperature is prevented from exerting an influence on the structural parts other than the light source. For this purpose, an exhaust fan  50  used for cooling the light source is arranged beside the discharge lamp  1  and the lamp reflector  3  so as to prevent the structural parts other than the light source from being influenced by the high temperature that is produced by the light source, and a high velocity air flow  45  is exhausted to the outside of the case  44  of light projector. The lamp power supply  31  is arranged beside the discharge lamp  1 . 
   In  FIG. 8 , the projection lens  27  and the cross-dichroic prism  25  are aligned from right to left. The color separation optical system comprises the first dichroic mirror  40 , the second dichroic mirror  15 , the first mirror  13 , the second mirror  19 , and the third mirror  20 , the color separation optical system being arranged around the cross dichroic prism  25 . 
   Further, the illumination optical system is designed to improve the utilization efficiency of the illumination light from the light source and to obtain uniform illumination light. The illumination optical system is formed by the discharge lamp  1  operating as a light source, the lamp reflector  3 , the lens  4 , the lens  5 , the polarizing conversion element  6 , the first lens array  7  that forms an optical integrator, the mirror  8 , and the second lens array  9 . In addition, there is a lamp power supply  31  that provides power for the light source. In  FIG. 8 , the projection lens  27 , the cross dichroic prism  25 , the color separation optical system, the illumination optical system and the lamp power  31  are arranged from the upper part to the lower part in this order. 
   In the embodiment shown by  FIG. 8 , the ventilation unit  61  is arranged on the left side of the projection lens  27  similar to the embodiment of  FIG. 1 , but it also may be arranged on the right side thereof. The intake of the air by ventilation unit  61  is drawn in as shown by arrow W 11 , and is ventilated in the case as shown an arrow W 12 . Therefore, this optical equipment can be miniaturized, and the height of the equipment can be reduced. In  FIG. 8 , the exhaust fan  50  can be removed or moved to another place. The ventilation unit  61  may be stationed between the projection lens  27  and discharge lamp  1 . 
   As explained above, in the optical equipment according to the present invention, the intake of cooling air is from a side face, and the intake air opening and the exhaust an opening are arranged on different side faces. Therefore, the air flow resistance of the optical equipment can be reduced and the cooling effect raised, while reducing height of the equipment. Further, because the ventilation path comprises a plurality of divided air flow paths in accordance with this invention, each of the first to third light valves  14 ,  18 ,  21  have individual air flow paths  101 ,  102 ,  103 ,  104 , respectively. Therefore, this invention is useful for miniaturization of the equipment and provision of thin-type equipment, and can provide optical equipment with a highly efficient cooling system. 
   Further, the present invention uses a centrifugal fan as the unit means  61  and provides divided flow paths to obtain a smooth flow of cooling air so as to reduce the air pressure loss at the incoming and outgoing light sides of each of the light valves. Accordingly, a sufficient air flow volume can be obtained. Further the present invention can provide an efficient cooling system and cut down on the height of the optical equipment. Accordingly, the present invention can reduce the height of the optical equipment and provide for miniaturization of the optical equipment, while at the same time providing the optical equipment with a high efficiency cooling system. Further, the optical equipment can cool a plurality of light valves to a substantially equal temperature.