Abstract:
A projector includes a plurality of lamps serving as light sources, the lamps being arranged next to each other, and a single exhaust fan disposed adjacent to the lamps, the exhaust fan discharging air around the lamps.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a projector and a method for cooling lamps installed in the projector. 
         [0003]    2. Description of the Related Art 
         [0004]    A projector is a display apparatus for projecting an image, and includes a high-intensity lamp as a light source. Light is caused to pass through, for example, liquid crystal panels and is emitted toward a screen or the like. A so-called two-lamp projector is an example of a projector according to the related art which includes two lamps. There are two types of two-lamp projectors: two-lamp projectors in which two lamps are simultaneously turned on to increase the brightness and two-lamp projectors in which only one of the two lamps is normally turned on and the other lamp is stored as an auxiliary lamp. 
         [0005]    The lamps mounted in the projectors emit heat when the lamps are turned on. Therefore, the temperature of the lamps and the inner spaces of the projectors increases. Accordingly, the projectors are provided with cooling systems including air supply fans and exhaust fans to cool the lamps and the inner spaces of the projectors. 
         [0006]    Japanese Unexamined Patent Application Publication No. 2007-108625 discloses a technique regarding a two-lamp projector, and describes the structure in which each of two lamps is provided with a single cooling fan. 
       SUMMARY OF THE INVENTION 
       [0007]    As illustrated in  FIGS. 5 and 6 , in a two-lamp projector according to the related art, lamps are disposed symmetrically to each other with an illumination optical system  20  disposed therebetween.  FIG. 5  is a plan view of a projector  10  according to the related art.  FIG. 6  is a perspective view of the projector  10  according to the related art.  FIGS. 5 and 6  schematically illustrate the main components of the projector  10  that are installed on a base  40  and exhaust fans  2 A and  2 B in the state in which an external housing of the projector  10  is removed. 
         [0008]    The projector  10  according to the related art includes lamp boxes  10 A and  10 B, the illumination optical system  20 , a projection optical system  30 , and the exhaust fans  2 A and  2 B. In the case where the projector  10  is of a two-lamp switching type, the projector  10  emits light from one of lamps mounted in the lamp boxes  10 A and  10 B. The lamps mounted in the lamp boxes  10 A and  10 B are arranged such that light emission directions thereof are opposed to each other. The light emitted from each lamp is divided into three light components corresponding to three primary colors (R, G, and B), and the thus-divided light components are caused to pass through liquid crystal panels and combined together in the illumination optical system  20 . The light obtained by combining the light components in the illumination optical system  20  passes through the projection optical system  30  as an image. The image is projected onto a screen or the like from the projection optical system  30  in a direction shown by the arrow in  FIG. 5 . 
         [0009]    In the projector  10  of the two-lamp switching type according to the related art, mirrors for switching between optical paths are disposed at a central position between the two lamp boxes  10 A and  10 B in the illumination optical system  20 . The optical arrangement of the lamp boxes  10 A and  10 B and the illumination optical system  20  can be easily designed. However, since the two lamp boxes  10 A and  10 B are separated from each other, the overall size of the projector  10  is relatively large. 
         [0010]    In addition, since the lamp boxes  10 A and  10 B are separated from each other, each of the lamp boxes  10 A and  10 B is provided with a cooling system for cooling the lamp contained therein. In particular, the exhaust fans  2 A and  2 B are arranged at positions corresponding to the positions of the lamp boxes  10 A and  10 B so that the air discharged from slits  12  of the lamp boxes  10 A and  10 B can be effectively discharged. As a result, at least two exhaust fans  2 A and  2 B are provided on an external housing  42  at positions near the lamp boxes  10 A and  10 B, and the exhaust fans  2 A and  2 B occupy a large space in the projector  10 . 
         [0011]    The temperature of the air discharged to the outside of the projector  10  is preferably low in consideration of the influence on the user and the external environment. However, in the projector  10  according to the related art, the distance from the lamp boxes  10 A and  10 B to the respective exhaust fans  2 A and  2 B is small. Therefore, it is difficult to reduce the temperature of the air discharged from the lamps that are turned on and that generate heat. As a result, the air is discharged to the outside of the projector  10  while the temperature thereof is relatively high. In addition, in the case where the operations of the exhaust fans  2 A and  2 B are not controlled in accordance with whether or not the lamps are turned on, when the lamps from which the air is discharged are not turned on, the exhaust fans  2 A and  2 B are uselessly operated even though no temperature change is caused. 
         [0012]    In light of the above-described situation, it is desirable to provide a new and improved projector in which the space occupied by a cooling system for lamps can be reduced so that the overall size can be reduced and the design freedom can be increased. In addition, it is also desirable to provide a method for cooling the lamps installed in the projector. 
         [0013]    According to an embodiment of the present invention, a projector includes a plurality of lamps serving as light sources, the lamps being arranged next to each other, and a single exhaust fan disposed adjacent to the lamps, the exhaust fan discharging air around the lamps. 
         [0014]    The projector may further include a heat transfer member disposed at an air discharge side of the lamps, air discharged from at least one of the lamps that is turned on and air discharged from at least one of the lamps that is not turned on coming into contact with the heat transfer member so that temperatures of the air discharged from the at least one of the lamps that is turned on and the air discharged from the at least one of the lamps that is not turned on are changed. 
         [0015]    The projector may further include box-shaped lamp boxes that accommodate the lamps. The lamp boxes may be provided with openings at the air discharge side of the lamps, the openings having side walls inclined toward the heat transfer member so that the air discharged from the lamps can easily flow toward the heat transfer member. 
         [0016]    According to another embodiment of the present invention, a method for cooling a plurality of lamps installed in a projector in which only one of the lamps is turned on, the lamps serving as light sources and being arranged next to each other, includes the step of mixing and discharging air around the lamp that is turned on and air around at least one of the lamps that is not turned on with a single exhaust fan disposed adjacent to the lamps. 
         [0017]    The method may further include the step of changing temperatures of air discharged from the lamp that is turned on and air discharged from the at least one of the lamps that is not turned on by bringing the air discharged from the lamp that is turned on and the air discharged from the at least one of the lamps that is not turned on into contact with a heat transfer member disposed at an air discharge side of the lamps. 
         [0018]    According to another embodiment of the present invention, a method for cooling a plurality of lamps installed in a projector in which the lamps are turned on, the lamps serving as light sources and being arranged next to each other, includes the step of mixing and discharging air around each of the lamps that are turned on with a single exhaust fan disposed adjacent to the lamps. 
         [0019]    As described above, according to the embodiments of the present invention, the space occupied by the cooling system for the lamps can be reduced. As a result, the overall size of the projector can be reduced and the design freedom can be increased. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a perspective view of a projector according to an embodiment of the present invention; 
           [0021]      FIG. 2  is a plan view of the projector according to the embodiment; 
           [0022]      FIG. 3A  is a side view of lamp boxes according to the embodiment; 
           [0023]      FIG. 3B  is a horizontal sectional view of the lamp boxes according to the embodiment; 
           [0024]      FIG. 4  is a vertical sectional view of air supply fans and one of the lamp boxes according to the embodiment; 
           [0025]      FIG. 5  is a plan view of a projector according to the related art; and 
           [0026]      FIG. 6  is a perspective view of the projector according to the related art. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functions are denoted by the same reference numerals and redundant explanations thereof are thus omitted. 
         [0028]    The explanations will be made in the following order: 
       1. Structure of Embodiment 
     2. Operation of Embodiment 
     1. Structure of Embodiment 
       [0029]    First, the structure of a projector  100  according to an embodiment of the present invention will be described.  FIG. 1  is a perspective view of the projector  100  according to the embodiment.  FIG. 2  is a plan view of the projector  100  according to the embodiment.  FIGS. 1 and 2  schematically illustrate the main components of the projector  100  that are installed on a base  140  and an exhaust fan  102  in the state in which an external housing of the projector  100  is removed. 
         [0030]    The projector  100  according to the present embodiment includes lamp boxes  110 A and  110 B, an illumination optical system  120 , a projection optical system  130 , and the exhaust fan  102 . The projector  100  is a display apparatus for projecting an image, and includes high-intensity lamps as light sources. Light is caused to pass through, for example, liquid crystal panels and is emitted toward a screen or the like. 
         [0031]    The projector  100  is of a two-lamp switching type in which only one of two lamps is normally used and the other lamp is stored as an auxiliary lamp. Therefore, when the projector  100  is used, only one of the lamps that is turned on generates heat and the temperature thereof increases. The other lamp that is not turned on does not generate heat. 
         [0032]    The lamp boxes  110 A and  110 E are box-shaped, and contain the lamps that serve as the light sources of the projector  100 . The lamps may be, for example, xenon lamps or extra-high-pressure mercury lamps. Light emitted from each lamp is output to the illumination optical system  120 . Since the projector  100  is of the two-lamp switching type, when the projector  100  is used, one of the lamps in the lamp boxes  110 A and  110 B is turned on the basis of, for example, the selection of the user or settings in the projector  100 . 
         [0033]    Unlike the projector  10  according to the related art, the lamp boxes  110 A and  110 B are arranged parallel to each other such that the two lamps contained in the lamp boxes  110 A and  110 B emit light in the same direction in the projector  100 . In addition, unlike the projector  10  according to the related art, the lamp boxes  110 A and  110 B are arranged next to each other. 
         [0034]    Since the projector  100  is of the two-lamp switching type, the illumination optical system  120  includes mirrors for switching between an optical path for the light from the lamp in the lamp box  110 A and an optical path for the light from the lamp in the lamp box  110 B. Since the arrangement of the lamp boxes  110 A and  110 B is different from that in the projector  10  according to the related art, the arrangement of the mirrors for switching between the optical paths for the light from the lamps differs from that in the projector  10  according to the related art. 
         [0035]    The illumination optical system  120  divides the light emitted from each lamp into three light components corresponding to three primary colors (R, G, and B). Then, the illumination optical system  120  causes the light components to pass through respective liquid crystal panels, so that image light components of the respective colors are generated. Then, the image light components are combined together into image light. The illumination optical system  120  outputs the combined image light to the projection optical system  130 . The illumination optical system  120  includes a UV cut filter, fly-eye lenses, mirrors, lenses, liquid crystal panels, and a cross prism. The illumination optical system  120  may have a structure according to the relate art except for the arrangement of the mirrors for switching between the optical paths of the light from the lamps. 
         [0036]    The projection optical system  130  includes, for example, a projecting lens, and projects the image light output from the illumination optical system  120  onto the screen or the like. 
       Cooling System of Projector  100   
       [0037]    A cooling system of the projector  100  will be described with reference to  FIGS. 1 to 4 .  FIGS. 3A and 3B  are a side view and a horizontal sectional view, respectively, of the lamp boxes  110 A and  110 B according to the present embodiment.  FIG. 4  is a vertical sectional view of air supply fans  106 A and  106 B and the lamp box  110 A according to the present embodiment. 
         [0038]    The cooling system of the projector  100  includes, for example, the air supply fans  106 A and  106 B, the exhaust fan  102 , and a heat transfer member  104 . 
         [0039]    The air supply fans  106 A and  106 B are, for example, centrifugal fans. The air supply fans  106 A and  106 B supply air to the lamps mounted in the lamp boxes  110 A and  110 B to cool the lamps that generate heat when the lamps are turned on. The air supply fans  106 A and  106 B are connected to, for example, the lamp box  110 A (or  110 B), as illustrated in  FIG. 4 . 
         [0040]    The two air supply fans  106 A and  106 B are respectively provided at the upper side and the lower side, as illustrated in  FIG. 4 . Accordingly, the lamp can be cooled from the upper and lower sides thereof. Although not shown in  FIG. 4 , ducts may be provided so as to extend from the air supply fans  106 A and  106 B to the lamp boxes  110 A and  110 B, and cooling air may be supplied from the air supply fans  106 A and  106 B to the lamp boxes  110 A and  110 B through the ducts. 
         [0041]    The exhaust fan  102  is, for example, an axial fan. The exhaust fan  102  sucks air supplied to the lamps in the lamp boxes  110 A and  110 B and discharges the air to the outside of the projector  100 . The exhaust fan  102  is attached to, for example, an external housing  142  of the projector  100 , as illustrated in  FIG. 4 . 
         [0042]    A single exhaust fan  102  is disposed near the lamp boxes  110 A and  110 B. The exhaust fan  102  is disposed at a position where the distance from the exhaust fan  102  to the lamp box  110 A is equal to the distance from the exhaust fan  102  to the lamp box  110 B. Accordingly, the air can be evenly discharged from the lamp boxes  110 A and  110 B. 
         [0043]    The exhaust fan  102  mixes the air from the lamp box  110 A with the air from the lamp box  110 B and discharges the mixed air. The exhaust fan  102  is disposed such that a gap is provided between the exhaust fan  102  and the lamp boxes  110 A and  110 B. Therefore, the air in the projector  100  other than the air in the lamp boxes  110 A and  110 B can also be discharged to the outside. Thus, the entire area of the projector  100  can be cooled by the exhaust fan  102 . 
         [0044]    The heat transfer member  104  is a plate-shaped member made of, for example, a metal having a high thermal conductivity. The heat transfer member  104  is disposed between the two lamp boxes  110 A and  110 B at the exhaust side thereof. As illustrated in  FIGS. 3A and 3B , the air discharged from the lamp box  110 A and the air discharged from the lamp box  110 B come into contact with the heat transfer member  104 . 
         [0045]    The heat transfer member  104  has a heat dissipation property, and is therefore capable of reducing the temperature of the air emitted from the lamp that is turned on and that generates heat. Since the projector  100  is of the two-lamp switching type, high-temperature air comes into contact with the heat transfer member  104  from one of the lamps that is turned on and that generates heat, and normal-temperature air comes into contact with the heat transfer member  104  from the other one of the lamps that is not turned on. Accordingly, the heat transfer member  104  is continuously cooled by the air with a relatively low temperature, and the air from the lamp that generates heat can be efficiently cooled. 
         [0046]    As illustrated in  FIGS. 1 ,  3 A, and  3 B, slits  112  are formed in the lamp boxes  110 A and  110 B at the exhaust side thereof. The slits  112  are openings formed in walls of the lamp boxes  110 A and  110 B. As illustrated in  FIGS. 3A and 3B , side walls of the slits  112  are inclined toward the heat transfer member  104 . Therefore, the air discharged from the lamps can easily flow toward the heat transfer member  104 . 
       2. Operation of Embodiment 
       [0047]    A method for cooling the lamps installed in the projector  100  according to the embodiment of the present invention will now be described with reference to  FIGS. 1 to 4 . 
         [0048]    Since the projector  100  is of the two-lamp switching type, when the projector  100  is used, one of the lamps in the lamp boxes  110 A and  110 B is turned on. The lamp that is turned on generates heat. When the projector  100  is activated, operations of the air supply fans  106 A and  106 B and the exhaust fan  102  of the projector  100  are started. 
         [0049]    The air supply fans  106 A and  106 B and the exhaust fan  102  operate so as to supply air to the lamp boxes  110 A and  110 B and discharge the air supplied to the lamp boxes  110 A and  110 B to the outside. Accordingly, one of the lamps that is turned on is cooled by the air flow. The air that passes by the lamp that is turned on is heated to a high temperature and is discharged from the lamp box  110 A or  110 B in a high-temperature state. The air that passes by the lamp that is not turned on is discharged from the lamp box  110 A or  110 B while the temperature thereof is maintained. 
         [0050]    Parts of the air discharged from the lamp box  110 A and the air discharged from the lamp box  110 B come into contact with the heat transfer member  104 . The heat transfer member  104  has a heat dissipation property, and is therefore capable of reducing the temperature of the air discharged from the lamp that is turned on and that generates heat. Since the normal-temperature air from the other lamp that is not turned on comes into contact with the heat transfer member  104 , the heat transfer member  104  is continuously cooled by the air with a relatively low temperature. Therefore, the air from the lamp that generates heat can be efficiently cooled. 
         [0051]    Then, the exhaust fan  102  mixes the air from the lamp box  110 A and the air from the lamp box  110 B, and discharges the mixed air to the outside of the projector  100 . Since the high-temperature air and the low-temperature air are mixed, the temperature of the air discharged to the outside is reduced to a temperature close to the room temperature (normal temperature). Also when the lamp that is turned on and the lamp that is not turned on are switched in accordance with the operation of the projector  100 , the same effect can be obtained. 
         [0052]    As illustrated in  FIGS. 5 and 6 , in the two-lamp projector  10  according to the related art, the lamps are disposed symmetrically to each other with the illumination optical system  20  disposed therebetween. Since the lamp boxes  10 A and  10 B are separated from each other, the cooling system for the projector  10  is structured such that the lamp boxes  10 A and  10 B are provided with the respective exhaust fans  2 A and  2 B for cooling the lamps. Therefore, a large space is occupied by the exhaust fans  2 A and  2 B in the external housing of the projector  10 . 
         [0053]    In contrast, according to the present embodiment, the two lamp boxes  110 A and  110 B are disposed next to each other and a single exhaust fan  102  is provided. As a result, an integrated exhaust structure is provided in the projector  100  and the space occupied by the exhaust fan  102  in the external housing of the projector  100  is reduced. Since the number of exhaust fans is reduced, the manufacturing cost can be reduced. In addition, the overall size of the projector  100  can be reduced and the design freedom can be increased. 
         [0054]    When a two-lamp switching type projector is used, one of the lamps is turned on and generates heat, and the other lamp is not turned on and does not generate heat. In the two-lamp switching type projector  10  according to the related art, the two exhaust fans  2 A and  2 B are provided for the respective lamps. Therefore, high-temperature air is discharged from one exhaust fan  2 A (or  2 B), and normal-temperature air is discharged from the other exhaust fan  2 B (or  2 A). Therefore, there is a case where high-temperature air, which is undesirable for the user and the external environment, is discharged. 
         [0055]    The two-lamp switching type projector  100  according to the present embodiment is similar to the two-lamp switching type projector  10  according to the related art in that one of the lamps is turned on and generates heat and the other lamp is not turned on and does not generate heat when the projector  100  is used. However, according to the present embodiment, the air that has passed by the lamp that is turned on and generates heat and the air that has passed by the lamp that is not turned on are mixed and are discharged together from a single exhaust fan  102 . Therefore, the temperature of the discharged cooling air can be reduced to a temperature close to the room temperature. 
         [0056]    According to the related art, the air that has passed by the lamp that is not turned on is directly discharged, and one exhaust fan  2 A (or  2 B) is unnecessarily operated. In contrast, in the present embodiment, the exhaust fan  102  is not unnecessarily operated since the exhaust fan  102  sucks the air from the two lamps. In addition, according to the present embodiment, the air with a relatively low temperature (normal temperature) that has passed by the lamp that is not turned on can be used to cool the air that has passed by the lamp that is turned on and that generates heat. 
         [0057]    Although the embodiment of the present invention is described in detail above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiment. 
         [0058]    For example, in the above-described embodiment, two lamp boxes and two lamps are provided in the projector. However, the present invention is not limited to this, and may also be applied to projectors including three or more lamp boxes and three or more lamps. In the case where, for example, three lamps are arranged next to each other, the exhaust fan may be disposed adjacent to the lamp at the center. 
         [0059]    In addition, although the two-lamp switching type projector is explained in the above-described embodiment, the present invention can also be applied to projectors in which the lamps are simultaneously turned on to increase the brightness. In this case, high-temperature air is discharged from each of the lamps that are turned on. However, an integrated exhaust structure can be provided in the projector  100  and the space occupied by the exhaust fan  102  in the external housing of the projector can be reduced. In addition, the air discharged by the lamps can be cooled by the heat transfer member  104 . Therefore, the temperature of the air discharged to the outside of the projector can be reduced. 
         [0060]    The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-298941 filed in the Japan Patent Office on Dec. 28, 2009, the entire contents of which are hereby incorporated by reference. 
         [0061]    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.