Abstract:
A lamp cooling apparatus for cooling a lamp may include a lamp outlet duct connected to the lamp, a lamp inlet duct connected to the lamp, a first joint segment provided at the front end of the lamp outlet duct, a second joint segment provided at the front end of the lamp inlet duct, a first pipe whose one end is adjustably connected to the first joint segment, a third joint segment to which the other end of the first pipe is shiftably connected, a cooling mechanism section for cooling air, connected to the third joint segment, a fourth joint segment connected to a discharge section for discharging air cooled by the cooling mechanism section, and a second pipe whose one end is shiftably connected to the fourth joint segment, and the other end is shiftably connected to the second joint segment.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from Japanese Patent Application No. 2006-257953 filed in the Japanese Patent Office on Sep. 22, 2006, the entire content of which is incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a lamp cooling apparatus cooling a lamp used as a light source, and to a projection display device provided with the lamp cooling apparatus.  
         [0004]     2. Description of Related Art  
         [0005]     Various types of image display devices called rear projection display devices have been produced. In these rear projection display devices, a transmission type screen is arranged on the front side of the device, and an image is projected from the back side on the screen. As an image to be projected, an image light corresponding to an image displayed on the display panel is generated by using a lamp such as a xenon lamp as a light source, and guiding the light from the light source to enter a liquid crystal display panel such that the light transmit or reflect the liquid crystal display panel. The generated image light is then guided to enter the back side of the screen to display the image on the screen. In the liquid crystal display panel, the image light may be generated by either one of the following manners. That is, individual panel is used per each primary color signal, and image lights generated at each color panels are combined, or single panel is used to generate the image lights of the respective colors. Instead of the liquid crystal panel, micro mirrors may be driven independently to transform the light from the light source to an image light.  
         [0006]     The abovementioned rear projection display devices enable relatively compact configurations of image light generating mechanism such as the light source or the liquid crystal display panel, and further enable the image to be displayed on a large screen. It is therefore relatively easy to obtain a device for displaying an image on a large screen. A screen size may be 50-inch or larger, for example.  
         [0007]     Japanese Patent Application Publication No. JP 11-84533 describes an example of this type of the rear projection display devices. Further, Japanese Patent Application Publication No. JP 2003-157715 describes an example of the configuration of a lamp and its vicinity used in the rear projection display devices.  
       SUMMARY OF THE INVENTION  
       [0008]     Meanwhile, as to the rear projection display devices, there are demands for a large size of the screen of the rear projection display device, and higher brightness of display images. Consequently, higher brightness light radiated from a lamp as a light source is demanded. Higher output of the power source for driving the lamp is required to increase the luminance of the lamp. The lamp has usually been driven at about 100 W, but in some cases, the lamp may be driven at a high power source of 200 W.  
         [0009]     As described above, if the output of the power source for driving the lamp becomes high, there is a problem that the heating value of the lamp increases proportionally. Thus, it is important to surely cool the lamp by a lamp cooling mechanism.  
         [0010]     On the other hand, an optical system, such as the lamp provided in the rear projection display device, is required to adjust an optical axis such that the light radiated from the lamp may be accurately projected to the setting position on the screen with the display panel in between. The optical axis adjustment is usually made in the manufacturing step in a factory. The setting position of the lamp in the rear projection display device is allowed to shift to some extent.  
         [0011]     There has been a problem of technical difficulty in achieving compatibility between the attainment of a mechanism to permit a shift of setting position of the lamp and the arrangement of the mechanism to surely cool the lamp. That is, to cool the lamp efficiently, a mechanism is required in that, a radiator as a cooling mechanism is placed in the vicinity of the lamp, the radiator and the lamp are connected with a duct, such that the air heated by the lamp may be flown into the radiator, and the air cooled at the radiator may be returned to the lamp. For the above mechanism, a closed path is required. The reason for circulating the air for cooling the lamp into the closed path is to prevent dirt and dust from entering the vicinity of the lamp. This is because if the dirt or dust enters an optical path in the vicinity of the lamp, dust may be reflected into an image projected to the screen, and thus the image quality of the display image may be lowered.  
         [0012]     Further, when the mechanism to permit the shift of the setting position of the lamp is provided for projection angle and projection range adjustments, it is necessary to provide a mechanism that enables the path of air for cooling the lamp to be changed in accordance with the setting position of the lamp. This extremely complicates the configuration to cool the lamp.  
         [0013]     In view of the foregoing issues, it may be desirable to surely and simply cool the lamp by providing a mechanism that enables the setting position of the lamp to be shifted for adjusting the projection angle and the projection range of an image light to be projected to the screen.  
         [0014]     According to an embodiment of the present invention, there is provided a lamp cooling apparatus which may include a lamp outlet duct connected to a lamp, and a lamp inlet duct connected to the lamp. A first joint segment may be provided at the front end of the lamp outlet duct. A second joint segment may be provided at the front end of the lamp inlet duct. The first and second joint segments may be connected to different pipes, in such a manner that the pipes are movable, and then connected to a cooling mechanism section via these pipes. The gas cooled by the cooling mechanism section may circulate between the lamp.  
         [0015]     With this configuration, when the setting position of the lamp is adjusted for adjusting the projection angle and the projection range of an image light to be projected to a screen, the state of connections of the pipes with the respective joint segments may be shifted to permit adjustments of the setting positions of optical components such as the lamp or the like, while maintaining them as the path for cooling air to flow. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is an external perspective view, viewed from the front of a rear projection display device according to an example of a preferred embodiment of the present invention;  
         [0017]      FIG. 2  is an external perspective view, viewed from the back of the rear projection display device in  FIG. 1 ;  
         [0018]      FIG. 3  is a perspective view, when the interior of the rear projection display device in  FIG. 1  is viewed from the back side;  
         [0019]      FIG. 4  is an explanatory drawing illustrating an example of the optical path of a projected image from the rear projection display device according to an embodiment of the present invention;  
         [0020]      FIG. 5  is a perspective view for explaining an example of situations how an optical unit is attached to a frame in the rear projection display device according to an embodiment of the present invention;  
         [0021]      FIG. 6  is a perspective view illustrating an example of the configuration of a lamp section attached to the optical unit in the example of  FIG. 5 ;  
         [0022]      FIG. 7  is a perspective view illustrating an example of a movable pipe according to an embodiment of the present invention;  
         [0023]      FIG. 8  is a disassembled perspective view illustrating, in a disassembled state, the movable pipe in  FIG. 7 ;  
         [0024]      FIG. 9  is a plan view of the movable pipe in  FIG. 7 , viewed from the side thereof;  
         [0025]      FIG. 10  is a sectional view of  FIG. 9 , specifically a schematic diagram for explaining the configuration of a lamp cooling apparatus in the rear projection display device according to an embodiment of the present invention; and  
         [0026]      FIG. 11  is an explanatory drawing illustrating an example of states how the movable pipe and joint segments are connected.  
     
    
     DETAILED DESCRIPTION  
       [0027]     A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.  
         [0028]      FIG. 1  shows a perspective view when viewed from the front side of a rear projection display device of the preferred embodiment.  FIG. 2  shows a perspective view when viewed from the back side of the rear projection display device. Further,  FIG. 3  shows a perspective view when the internal configuration of the rear projection display device is viewed from the back side.  
         [0029]     In this embodiment, an image display screen of the rear projection display device has a size of 50-inch, and the depth thereof is as thin as 30 cm, for example.  
         [0030]     In FIGS.  1  to  3 , reference numeral  1  represents a rear projection display device. As shown in  FIG. 1 , the rear projection display device  1  has a screen  3  on the front side, and is provided with an outer frame  4  and a cover frame  6  on the front side, and a rear cover  5  on the back side. In this embodiment, the outer frame  4 , the cover frame  6  and the rear cover  5  form a cabinet or an outer case of the rear projection display device.  
         [0031]     The screen  3  is produced in such a manner that a front transparent glass plate and a back transparent glass plate keep predetermined space in between. The front transparent glass plate has a lusterless finished surface, and a back to which a lenticular sheet is attached. The back transparent glass sheet has a Fresnel lens sheet attached to the back side of the screen  3 .  
         [0032]     Further, as shown in  FIG. 1 , the cover frame  6  having a rectangular shape is mounted around the screen  3  on the front side, and more further, the outer frame  4  having an oblong rectangular shape is mounted around the cover frame  6 . The rear cover  5  is disposed on the back of the screen  3  to cover the whole of the back, as shown in  FIG. 2 .  
         [0033]     In  FIG. 1 , reference numeral  7  represents a leg cover of the rear projection display device  1 .  
         [0034]     As shown in  FIG. 2 , the rear cover  5  provided on the back side of the rear projection display device  1 , has a mirror adjusting section cap  5   a  disposed at the upper part of the rear cover  5 , a box-shape recessed cover  5   b  for housing an electric circuit unit (not shown), and an air cooling fan cover  5   c  disposed at a position corresponding to an air cooling fan unit which is provided in a lamp house  58  in order to cool a radiator  200 , which will be described later.  
         [0035]     Further, as shown in  FIG. 2 , a speaker unit  8  provided integrally with a decorative panel on the front side is disposed in a lengthwise region formed between the left outer frame  4  and the right rear cover  5 .  
         [0036]      FIG. 3  shows a situation where the rear cover  5  is removed. In the configuration shown in  FIG. 3 , on the back of a bottom frame  11 , there are the lamp house  58 , an air-cooling fan unit  57 , and an optical unit  50 . The optical unit  50  resolves the light of the lamp into three primary colors of light, red (R), green (G) and blue (B), and generates and then synthesizes three color images through three liquid crystal panels (not shown), and thereafter projects these images from a projection window  51 . In the present embodiment, the three liquid crystal panels are reflective-type liquid crystal display panels. It is noted, in  FIG. 3 , reference numeral  55  represents a projection control circuit board for controlling the images of the three liquid crystal panels built in the optical unit  50 .  
         [0037]     As shown in  FIG. 3 , on the back, a left frame support  16  is disposed between a left side frame  12  and the bottom frame  11 , and a right frame support  15  is disposed between a right side frame  13  and the bottom frame  11 . Further, a shade plate  18  is disposed between the bottom frame  11  and the left and right side frames  12  and  13 . The shade plate  18  has two functions: avoiding the influence of the light leaked from the optical unit  50  on the screen  3 , and reinforcing the abovementioned frames.  
         [0038]     A mirror support  17  made of a sheet metal subjected to bending is disposed at the upper ends of the left and right side frames  12  and  13 , respectively, as shown in  FIG. 3 . The bent shape of the mirror support  17  when viewed from above is arranged to form a trapezoidal shape frame by a top frame  14 . A mirror fixing plate  19  is provided at nearly centrally between the top frame  14  and the mirror support  17  so as to bridge therebetween.  
         [0039]     The principle of projection of an image light to the screen  3  under the abovementioned configuration will be described with reference to  FIG. 4 .  
         [0040]      FIG. 4  shows the inside of a mirror housing section  61  ( FIG. 5 ) in the optical unit  50 , and the process where the light emitted from the mirror housing section  61  is projected to the back of the screen  3 . The light from the lamp is reflected at the liquid crystal panels and then synthesized, and thereafter guided to enter a flat mirror  52  in the mirror housing section  61  as shown in  FIG. 5 . In  FIG. 4 , the optical path up to where the light enters the flat mirror  52  is omitted. The optical path is bent about 90 degrees by the flat mirror  52 , and then the light enters a convex mirror  53 . The light with the image reflected from the convex mirror  53  is further reflected at an aspherical mirror  54 , and passes through the projection window  51  shown in  FIG. 3 . This light is then reflected at a flat mirror  31 , which is one of the components of a projection mirror  30 , and projected to the screen  3  on the front.  
         [0041]     The optical unit  50 , thus generating the image light to be projected to the screen  3 , is configured to permit its position adjustment relative to the bottom frame  11 .  
         [0042]     That is, as shown in  FIG. 5  as a perspective view, the optical unit  50  includes the mirror housing section  61  having the projection window  51 , a projection lens housing section  62 , a liquid crystal projection device  63 , a capture section  64 , a lamp  90  (refer to  FIG. 6 ) for supplying light to the capture section  64 , and a base block  60  disposed below the mirror housing section  61 . The projection lens housing section  62  is integrally provided with the mirror housing section  61 , and houses a projection lens (not shown). The liquid crystal projection device  63  synthesizes different image signals of three colors, R, G and B, and emits the light of a color image to the projection lens housing section  62 . The capture section  64  performs color adjustment of the light from the light source, and supplies white light to the liquid crystal projection device  63 .  
         [0043]     The lamp  90  is attached and positioned, through an adaptor  85 , to the capture section  64  of the optical unit  50 . The liquid crystal projection device  63  and the capture section  64  in the optical unit  50  are assembled in advance such that a specified positional relation is mutually kept with positioning pins or the like (not shown), and then positioned and fixed to the base block  60 . The mirror housing section  61  and the projection lens housing section  62  are, in the integrated state thereof, positioned and fixed to the base block  60 .  
         [0044]     The optical unit  50  is mounted such that the base block  60  may be rotatably engaged with a rotation shaft  70  as a rotating reference provided on the bottom frame  11  of a frame structure, as shown in  FIG. 5 . In the optical unit  50 , fixing pins  65 , each having a compression coil spring  66  as a first elastic body, are engaged to three locations in the periphery of the base block  60 , respectively. This enables the optical unit  50  to move slightly around the rotation shaft  70 , with secure engagement of the optical unit  50  on the bottom frame  11 .  
         [0045]     That is, the rear projection display device of the present embodiment is configured to make adjustments of the projection angle and the projection range of an image by rotation and slight movement of the base block  60  of the optical unit  50  on the rotation shaft  70 . Although in  FIG. 5 , there is shown a situation where the lamp  90  is not attached to the optical unit  50 , the lamp  90  is attached to the capture section  64  with the adaptor  85  shown in  FIG. 6  in between. In situations where the lamp  90  is attached, the lamp  90  is integrally rotated with the optical unit  50  around the rotation shaft  70 , by adjusting the projection angle and the projection range of the image.  
         [0046]     Each of the fixing pins  65  has the compression coil spring  66  as the first elastic body, which is disposed between two washers  67  and  67 . Thus, a large pressing force resulting from the force exerted by the compression coil springs  66  may be generated when the fixing pins are fixed to the three locations in the periphery of the base block  60 . A pressing mechanism includes the fixing pins  65 , the two washers  67  and  67 , and the compression coil springs  66 .  
         [0047]     The configuration of the lamp  90  and the cooling mechanism for air-cooling the lamp  90  will be described with reference to  FIG. 6  and the succeeding drawings.  
         [0048]      FIG. 6  shows an adaptor  80  of the lamp  90 , which is attached to the capture section  64  of the optical unit  50 , and the configuration in the vicinity of the adaptor  80 . A portion of the lamp  90  is integrally attached to the optical unit  50  shown in  FIG. 5 , and integrally rotates together when the projection angle or the projection range of an image are adjusted. In contrast, a radiator  200  for cooling the lamp  90  is fixed to the bottom frame  11 , and does not move even when the projection angle or the projection range is adjusted. In  FIG. 6 , the broken line represents a part of the radiator  200 .  
         [0049]     The adaptor  80  shown in  FIG. 6  is positioned in the lamp house  58  shown in  FIG. 3 . By forcing the lamp  90  into the lamp house  58 , the electrodes of the lamp  90  are connected to a power supply line on the side of the optical unit  50 , with a connector (not shown in the figure) equipped at the adaptor  80  in between.  
         [0050]     Although the detail of the lamp  90  is not shown in a figure, the lamp  90  has the following configuration. That is, light-emitting elements (electrodes) as a light source are provided in a reflector as a reflecting member, and a hole for introducing air for cooling into the reflector, and a hole for discharging the air for cooling to the exterior are provided in the reflector. A duct  101  shown in  FIG. 6  is connected to the hole for discharging the air for cooling to the exterior, and a tubular duct  102  is connected to the duct  101 . The ducts  101  and  102  are formed by resin.  
         [0051]     A spherical joint segment  103  is provided at the front end of the duct  102 . Joint segments  105 ,  211  and  212  described later have the same shape. One end of a movable pipe  110  is shiftably inserted and connected to the spherical joint segment  103 .  
         [0052]     The movable pipe  110  is extendable, and its both ends are spherical. When the movable pipe  110  is press-inserted into the spherical joint segment, it is rotatably connected to the joint segment. The detailed shape of the movable pipe  110  will be described later.  
         [0053]     The other end of the movable pipe  110  is rotatably connected to the joint segment  211  on the side of the radiator  200 . The joint segment  211  is connected to the upper end of a metal cylinder  220  with a duct  201  in between. The metal cylinder  220  in the radiator  200 , which constitutes the cooling mechanism, is made of a metal material having a high thermal conductivity, such as aluminum, and a plurality of heat absorbing fins are provided in the metal cylinder. On the outside of the metal cylinder  220  of the radiator  200 , a cooling fan unit  57  shown in  FIG. 3  is provided to discharge the ambient air around the metal cylinder  220  to the exterior. A blower  230  is connected to the lower end of the metal cylinder  220 . The blower  230  sucks air from the lower end of the metal cylinder  220 , and pushes air to the duct  202  connected to the blower  230 .  
         [0054]     The joint segment  212  is connected to the front end of the duct  202 . One end of a movable pipe  120  is rotatably connected to the joint segment  212 . The other end of the movable pipe  120  is rotatably connected to the joint segment  105 , which is the front end of a duct  104  on the side of the optical unit  50 . The duct  104  is connected to the hole for introducing the air for cooling the lamp  90 , and introduces the air supplied from the blower  230  into the lamp  90  with the hole in between.  
         [0055]     With this configuration, when the blower  230  is operated, the air cooled in the metal cylinder  220  and then exhausted from the blower  230  is fed into the reflector of the lamp  90  through the duct  202 , the movable pipe  120  and the duct  104 . The air discharged from the reflector of the lamp  90  is cooled by being fed into the metal cylinder  220  in the radiator  200  through the duct  101 ,  102 , the movable pipe  110  and the duct  201 . Thus, the closed path of air (gas) for cooling the lamp  90  is configured.  
         [0056]      FIG. 7  shows an example of the configuration of the movable pipe  110 . This is common to the movable pipe  120  in the present embodiment. The movable pipes  110  and  120  are components formed by resin. The movable pipe  110  is formed by a combination of three members  111 ,  112  and  113 .  FIG. 8  shows a state where these three members  111 ,  112  and  113  are disassembled.  FIG. 9  is a side view of the state of  FIG. 7 .  FIG. 10  is a sectional view of the state of  FIG. 9 . As shown in these drawings, the spherical members  111  and  112  are connected to each other with the cylindrical member  113  in between. In the spherical member  111 , a cavity  111   b  is formed in a spherical segment  111   a , and a cylindrical member connecting segment  111   c  is formed at the rear end of the cavity  111   b . Similarly, in the spherical member  112 , a cavity  112   b  is formed in a spherical segment  112   a , and a cylindrical member connecting segment  112   c  is formed at the rear end of the cavity  112   b . The cylindrical member  113  has an end segment  113   a  to be inserted into the connecting segment  111   c  of the spherical member  111 , another end segment  113   b  to be inserted into the connecting segment  112   c  of the spherical member  112 , and a central flange segment  113   c . A cavity  113   d  is formed on the inside of the cylindrical member  113 . The cavities  111   b ,  112   b  and  113   b  in these members  111 ,  112  and  113 , respectively, form a flow path for the air for cooling.  
         [0057]     Referring to  FIGS. 9 and 10 , the connection or joining is made by inserting the one end segment  113   a  of the cylindrical member  113  into the spherical member  111 . The connection is adjustable by freely setting the amount of insertion as indicated by the arrow a in  FIG. 9 . Similarly, the connection is made by inserting another end segment  113   b  of the cylindrical member  113  into the spherical member  112 . The connection may be adjustable by freely setting the amount of insertion as indicated by the arrow b in  FIG. 9 . Therefore, the movable pipe  110  has an extendable construction. The spherical segments  111   a  and  112   a  of the spherical members  111  and  112  in the present embodiment are provided with grooves arranged in parallel and at predetermined intervals to reduce the amount of the resin material for use, but alternatively, there may be a case where these grooves are not provided.  
         [0058]      FIG. 11  shows a state where the movable pipe  110  thus constructed is attached to the joint segments  103  and  211 . As shown in  FIG. 11 , the spherical segment  111   a  of the spherical member  111  of the movable pipe  110  is fit in a spherical hole segment  211   a  of the joint segment  211  on the side of the radiator. Also, the spherical segment  112   a  of the spherical member  112  of the movable pipe  110  is fit in a spherical hole segment  103   a  of the joint segment  103  on the side of the lamp. Each of the joint segments is shiftable such that the angle formed with the movable pipe  110  may be freely adjustable as indicated by the angles θ 1  and θ 2  in  FIG. 11 . Further, the movable pipe  110  itself is freely extendable as indicated by the arrows a and b in  FIG. 11 . Similarly with the state of  FIG. 11 , connection between another movable pipe  120  and the joint segments  212  and  105  may be adjustable.  
         [0059]     In the above configuration, the movable pipe is used to connect the duct  201  connected to the side of the radiator fixed to the bottom frame in the rear projection display device, and the duct  103  connected to the side of the lamp which is shiftable for adjustments of the projection angle and the projection range with respect to the screen. Accordingly, even if the position of the side of the lamp is shifted for adjustments, the connection state with ducts may be maintained by movements indicated by the angles θ 1  and θ 2 , and the movements indicated by the arrows a and b, and the closed line configuration for flowing the air for cooling is retained.  
         [0060]     According to embodiments described above, the optical block in the rear projection display device may be rotatable for adjustments of the projection angle and the projection range to the screen. Even when the adjustments are made by the rotation of the optical block, the position of the flow path of the air for cooling the lamp, such as the duct provided in the optical block is fixed to permit continuous connection to the side of the radiator, and thus, the lamp may be efficiently cooled.  
         [0061]     It is noted that shapes of the respective members in the foregoing embodiments are described by way of an example, and their shapes may be changed as long as they are members having the same function. For example, the movable pipe shown in  FIGS. 7 and 8  is moved by the connection of three members, but instead, there may be a case where a movable pipe may be moved by connecting two members.  
         [0062]     Also, in the overall configuration of the rear projection display device, the projection mirror is provided on the upper portion in forgoing embodiment, as shown in  FIG. 4 , but there may be a case where the projection mirror is provided on the rear (on the side of the rear cover). Additionally, any cooling means other than the radiator  200  shown in  FIG. 6  may be employed as a cooling mechanism.  
         [0063]     According to an embodiment of the present invention, there is provided an excellent configuration in which the compatibility is kept between the mechanism that the path of the air for cooling may be maintained to retain the cooling performance of the lamp, and the mechanism that the projection angle or the projection range may be adjusted, even though the setting positions of the optical components such as the lamp or the like are adjusted.  
         [0064]     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.