Abstract:
A projector apparatus, including: a light source including a high-pressure discharge lamp having a plurality of ventilation holes; an optical unit having a liquid crystal panel for optically modulating to light emitted from the light source in response to an input video signal; a ventilation fan; and cooling means for cooling the light source by blowing cooling-air blown from the ventilation fan to at least the light source, wherein a cooling-air ventilation inlet facing one ventilation hole of the high-pressure discharge lamp is formed at an upper position of a lamp case, which holds and fixes the high-pressure discharge lamp having the plurality of ventilation holes and positions and fixes the optical unit, a cooling-air ventilation outlet facing another ventilation hole of the high-pressure discharge lamp is formed at a lower position of the lamp case, and a tray is provided under the cooling-air ventilation outlet.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a projector apparatus for projecting and displaying an image on a screen or the like by irradiating light from a light source accommodated in a housing to a transmission type liquid crystal panel. 
   2. Description of Related Art 
   A projector apparatus uses three transmission type liquid crystal panels for controlling colors, e.g., red, green and blue, synthesizes these three color components, and magnifies and projects the synthesized light through a lens.  FIG. 2  is a schematic diagram showing an optical system of a general projector apparatus. From illumination light L emitted from a light source  1 , red light R is separated and reflected by a dichroic mirror  2   a . The separated and reflected red light R is reflected by a reflecting mirror  3   a  and reaches a transmission type liquid crystal panel  4   a  for red color. 
   As for green light G and blue light B transmitted through the dichroic mirror  2   a , green light G is separated and reflected by a dichroic mirror  2   b . The separated and reflected green light G reaches a transmission type liquid crystal panel  4   b  for green color. On the other hand, the blue light B transmitted through the dichroic mirror  2   b  is reflected by a reflecting mirror  3   b , passed through a lens  5 , is reflected by a reflecting mirror  3   c , and reaches a transmission type liquid crystal panel  4   c  for blue color. 
   The red light R, green light G and blue light B are optically modulated when they transmit through the transmission type liquid crystal panels  4   a ,  4   b  and  4   c , respectively, which panels are driven by a drive circuit in response to red, green and blue video signals, respectively. Thereafter, colors of respective optically modulated light are color-synthesized by a complex prism  6 , and color-synthesized light is magnified and projected on a screen  17  by a magnifying/projecting lens (not shown). In this manner, an image can be displayed on the screen  17 . In the projector apparatus, an optical axis of the light source  1  and an optical axis of an optical system are made coincident, by forming a positioning hole in one of a case accommodating the light source and a case accommodating the optical system, such as the dichroic mirror  2   a , placed behind the former case, and forming a positioning pin on the other. 
   The light source used here is a high-pressure discharge lamp, such as a metal halide lamp and a super high-pressure mercury lamp, to which a relatively high-pressure discharge gas is sealed. This high-pressure discharge lamp (hereinafter simply called a “lamp”) is, for example, a lamp  100  having an appearance such as shown in  FIG. 8 , and a glass bulb  101  with a swelled portion  101   a  is mounted upright at the center of a concave mirror  105 . The swelled portion  101   a  of the glass bulb  101  in which gas is sealed becomes a light emission region. One end of the glass bulb  101  is electrically connected to a male screw  104  via a metal member  103 , and the other end at the top of the glass bulb  101  is connected to an electrode terminal  102  on a mirror outer surface  106  of the lamp  100  via a hole formed through the concave mirror  105 , to thereby supply a discharge voltage. A flat glass  107  is mounted in front of the lamp  100 . 
   The glass  107  has ventilation holes  100   a  and  100   b  of semicircular openings formed inside the glass  107  and at upper and lower positions of the concave mirror  105 . The ventilation holes  100   a  and  100   b  form a ventilating duct for air-cooling the light emission region, the ventilating duct extending vertically in the lamp  100 . The ventilation holes  100   a  and  100   b  forcibly air-cool the glass bulb  101  and its nearby area, the glass bulb  101  is driven at a startup discharge voltage of 250 kV and at a high voltage of several kV even at a discharge voltage during a stable operation, and has a high temperature. Glass of the glass bulb  101  containing sealed discharge gas is deteriorated with a long term usage, and the glass bulb  101  itself may be broken due to its lifetime or the like. The glass  107  on the lamp front side is provided also for protection from scattered matters when the glass bulb  101  happens to be broken. 
   However, when the glass bulb is broken, pieces of broken glass or the like stray and spread widely into the optical unit via the ventilation holes of the lamp in some cases to deteriorate the optical performance. To address this drawback, various studies have been made. For example, Japanese Patent Application Publication No. 2001-183746 (page 2, FIGS. 6 and 7) discloses a technique by which the optical performance is prevented from being deteriorated by pieces of broken glass and the like scattered from a cooling-air inlet port to the inside of an outer housing of a projector apparatus. Japanese Patent Application Publication No. 2001-183746 discloses a lamp box accommodating a light source and removably mounted in the outer housing, which lamp box is provided with: a transparent protective member disposed at a light output port of a light source; a cooling-air inlet port for guiding cooling-air from cooling means to the light source; and automatic shutter means mounted at the cooling-air inlet port for automatically opening the cooling-air inlet port by mounting the lamp box in the outer housing and automatically closing the-cooling-air inlet port by dismounting the lamp box from the outer housing. 
   SUMMARY OF THE INVENTION 
   In the lamp box of the projector apparatus disclosed in Japanese Patent Application Publication No. 2001-183746, the shutter is closed when a ventilation duct extending from a ventilation fan for air-cooling a lamp is not coupled to the cooling-air inlet port of the lamp box, and the shutter is opened during a normal use while the lamp box is mounted and its cooling-air outlet port is connected. In other words, glass bulb breakage is very unlikely but usually happens during the normal use. During the normal use, the connected shutter remains open so that pieces of broken glass may enter into the ventilation duct and an optical unit case integrally formed with the upper part of the ventilation duct from the cooling-air inlet port of the lamp box. Therefore, there is difficulty in avoiding the deterioration of the optical system performance perfectly. 
   Under these circumstances, the present invention proposes a projector apparatus capable of forcibly and efficiently cooling a light emission region and mitigates the influence of pieces of broken glass of a lamp without sacrificing a cooling efficiency. 
   In order to solve these issues, a projector apparatus according to an embodiment of the present invention includes: a light source including a high-pressure discharge lamp having a plurality of ventilation holes; an optical unit having a liquid crystal panel for optically modulating to light emitted from the light source in response to an input video signal; a ventilation fan; and cooling means for cooling the light source by blowing cooling-air blown from the ventilation fan to at least the light source, wherein a cooling-air ventilation inlet facing one ventilation hole of the high-pressure discharge lamp is formed at an upper position of the lamp case, which holds and fixes the high-pressure discharge lamp having the plurality of ventilation holes and positions and fixes the optical unit, a cooling-air ventilation outlet facing another ventilation hole of the high-pressure discharge lamp is formed at a lower position of the lamp case, and a tray is provided under the cooling-air ventilation outlet. 
   The projector apparatus according the embodiment, wherein the cooling means has a ventilation duct for blowing cooling-air blown from the ventilation fan to at least the light source. 
   The projector apparatus according to the embodiment, wherein the ventilation fan is a sirocco fan. 
   According to another embodiment of the present invention, a projector apparatus for displaying an image on a screen disposed on an outer surface of a housing by using a liquid crystal panel, includes: a light source including a high-pressure discharge lamp having a plurality of ventilation holes; an optical unit having the liquid crystal panel for optically modulating to light emitted from the light source in response to an input video signal; a ventilation fan; and cooling means for cooling the light source by blowing cooling-air blown from the ventilation fan to at least the light source, wherein a cooling-air ventilation inlet facing one ventilation hole of the high-pressure discharge lamp is formed at an upper position of the lamp case, which holds and fixes the high-pressure discharge lamp having the plurality of ventilation holes and positions and fixes the optical unit, a cooling-air ventilation outlet facing another ventilation hole of the high-pressure discharge lamp is formed at a lower position of the lamp case, and a tray is provided under the cooling-air ventilation outlet. 
   The projector apparatus according to another embodiment, wherein the cooling means has a ventilation duct for blowing cooling-air blown from the ventilation-fan to at least the light source. 
   The projector apparatus according to another embodiment, wherein the ventilation fan is a sirocco fan. 
   According to the projector apparatus constructed as above, a glass bulb can be cooled by introducing cooling-air from the ventilation fan into the ventilation hole disposed at an upper position of the lamp via a duct disposed above the cooling-air ventilation inlet of a light source unit and exhausting the cooling-air via the cooling-air ventilation outlet under the other ventilation hole, and the tray disposed under the cooling-air ventilation outlet can accumulate pieces of broken glass if the glass bulb is broken. 
   According to the projector apparatus of the present invention, the glass bulb of the high-pressure discharge lamp can be cooled efficiently, and even if the glass bulb is broken, pieces of broken glass and the like can be accumulated in the tray so that it is possible to avoid damages to an optical system and damages to an external to be caused by pieces of broken glass and the like exhausted to an outside of the projector apparatus. 

   
     BRIEF-DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic side view showing an internal structure of a projector apparatus according to an embodiment of the present invention; 
       FIG. 2  is an illustrative diagram showing an optical system of a general projector apparatus; 
       FIG. 3  is an external perspective view illustrating amount state of a lamp case on an optical unit of the projector apparatus shown in  FIG. 1 ; 
       FIG. 4  is an external perspective view of the lamp case accommodating a lamp of the projector apparatus shown in  FIG. 1 ; 
       FIG. 5  is an exploded perspective view of the lamp case accommodating the lamp shown in  FIG. 4 ; 
       FIG. 6  is a side view showing a mount state of the lamp case of the projector apparatus shown in  FIG. 3 ; 
       FIG. 7  is a side cross sectional view showing the lamp case and a partial ventilation duct shown in  FIG. 6 ; and 
       FIG. 8  is a perspective view of a high-pressure discharge lamp used in the projector apparatus shown in  FIG. 1 . 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   With reference to  FIGS. 1 to 8 , description will be made on an embodiment to implement a projector apparatus according to the present invention. 
   First, with reference to  FIGS. 1 and 2 , the outline of the projector apparatus of the embodiment will be described.  FIG. 1  is a schematic side view showing an internal structure of the projector apparatus of the embodiment, and  FIG. 2  is an illustrative diagram showing an optical system of the projector apparatus. 
   Referring to  FIG. 1 , a projector apparatus  10  is a so-called three-panel liquid crystal projector apparatus using three transmission type liquid crystal panels. The projector apparatus  10  has a housing  11 . A screen  17  is disposed on the front side of an upper portion  12  of the housing  11 , and a mirror  15  is disposed on the inner back side of the upper portion  12  of the housing  11 . An optical unit  130  and a lamp case  200  coupled to the optical unit are disposed in an inner central area of a lower portion  13  of the housing  11 , and electronic circuits, a cooling fan and the like (not shown) are disposed near the optical unit and lamp case. A lamp case inlet/outlet port  14  is provided on the front side of the lower portion  13  of the housing  11  to replace the lamp case  200  or the like. 
     FIG. 2  is an illustrative diagram showing an optical system of the projector apparatus. Referring to  FIG. 2 , from illumination light L emitted from a light source  1 , red light R is separated and reflected by a dichroic mirror  2   a . The separated and reflected red light R is reflected by a reflecting mirror  3   a  and reaches a transmission type liquid crystal panel  4   a  for red color. From green light G and blue light B transmitted through the dichroic mirror  2   a , green light G is separated and reflected by a dichroic mirror  2   b . The separated and reflected green light G reaches a transmission type liquid crystal panel  4   b  for green color. On the other hand, the blue light B transmitted through the dichroic mirror  2   b  is reflected by a reflecting mirror  3   b , passed through a lens  5 , is reflected by a reflecting mirror  3   c , and reaches a transmission type liquid crystal panel  4   c  for blue color. 
   The red light R, green light G and blue light B are optically modulated when they transmit through the transmission type liquid crystal panels  4   a ,  4   b  and  4   c , respectively, which panels are driven by a drive circuit in response to red, green and blue video signals, respectively. Thereafter, colors of respective optically modulated light are color-synthesized by a complex prism  6 , and color-synthesized light is magnified and projected by a projecting lens  131  (refer to  FIG. 1 ) disposed at the subsequent stage of the complex prism  6 . Light transmitted through the projecting lens  131  is reflected by the mirror  15  and magnified and projected on a back side (inner side) of a screen  17 . In this manner an image can be displayed on the screen  17  (refer to  FIG. 1 ). 
   Next, the lamp case  200  of the embodiment will be described with reference to  FIGS. 3 to 8 .  FIG. 3  is an external perspective view illustrating a mount state of lamp case  200  on the optical unit  130 ,  FIG. 4  is an external perspective view of the lamp case  200 ,  FIG. 5  is an exploded perspective view of the lamp case  200 ,  FIG. 6  is a side view showing the mount state of the lamp case  200  shown in  FIG. 3 , and  FIG. 7  is a partial side cross sectional view of the lamp case  200  shown in  FIG. 6 . 
   As shown in  FIG. 3 , the lamp case  200  is coupled to the optical unit  130  as a different unit and mounted on the same side as that of the projecting lens  131  optically integral with the optical unit  130 . An opening of a ventilation duct  135   a  of a ventilation fan unit  135  mounted above the optical unit  130  faces a cooling-air ventilation inlet  201   a  (refer to  FIG. 4 ) formed in an upper portion of the lamp case  200  so that cooling-air can be supplied to the inside of the lamp case  200 . As shown in  FIGS. 4 and 5 , the lamp case  200  is constituted of a front case  201  and a rear case  202 . A high-pressure discharge lamp  100  is accommodated and fixed in the lamp case. 
   The high-pressure discharge lamp (hereinafter simply called a lamp)  100  may be a metal halide lamp or a super high-pressure mercury lamp having a relatively high-pressure of discharge gas sealed in the lamp, and has, for example, an appearance such as shown in  FIG. 8 . A glass bulb  101  with a swelled portion  101   a  is mounted upright at the center of a concave mirror  105 . The swelled portion  101   a  of the glass bulb  101  in which discharge gas is sealed becomes a light emission region. One end of the glass bulb is electrically connected to a male screw  104  protruding from a metal member  103 , and the other end at the top of the glass bulb  101  is connected to an electrode terminal  102  on a mirror outer surface  106  of the lamp via a hole formed through the concave mirror  105 , to thereby supply a discharge voltage. A flat glass  107  is mounted in front of the lamp. 
   The glass  107  disposed on the lamp front side has ventilation holes  100   a  and  100   b  of semicircular openings (shown in  FIG. 8 ) formed at upper and lower positions of the concave mirror  105 . The ventilation holes form a ventilating duct for air-cooling the light emission region, the ventilating duct extending vertically in the lamp  100 . The ventilation holes forcibly air-cool the glass bulb  101  driven at a startup discharge voltage of 250 kV and at a high voltage of several kV even at a discharge voltage during a stable operation and has a high temperature. Glass of the glass bulb  101  containing sealed discharge gas is deteriorated with a long term usage, and the glass bulb  101  itself may be broken before it is replaced with a new lamp  100 . The glass  107  on the lamp front side is provided also to prevent pieces of broken glass from scattering toward the optical unit  130  when the glass bulb  101  happens to be broken. 
   As shown in  FIG. 5 , ends of wiring are fixed to the male screw  104  and electrode terminal  102  of the lamp  100 , respectively, with screws, and the other ends are connected to a connector  110  having two terminals. Since the wiring have also a high temperature during lamp turn-on, heat resistance coating material is selected for the wiring. 
   As shown in  FIG. 5 , the front case  201  is a short tube having an approximately rectangular cross section and a frame formed on one open end thereof. A cooling-air ventilation inlet  201   a  of approximately a rectangular shape is formed in an upper wall  201 - 1  of the tube placed laterally, and a cooling-air ventilation outlet  201   b  of approximately a rectangular shape is formed in a lower wall  201 - 2 . On the lower wall  201 - 2 , the cooling-air ventilation outlet  201   b  and a tray  201   d  are mounted. The tray  201   d  is made of a tube whose opening is disposed laterally, and is formed integrally with the lower wall  201 - 2  of the front case  201 . A wall  201   e  is formed extending upward from the lower side and covering a lower portion of the opening on the frame side, and an opening  201   j  is formed through this wall (refer to  FIG. 7 ). 
   As shown in  FIG. 4 , on the side where the frame of the tube is formed, two positioning projections  201   f  and  201   f  are formed and one gap setting projection  201   g  is formed. In the inner side of the frame, screw holes (not shown) are formed to fix the lamp  100 . Two engaging members  201   h  and  201   h  for fixing and positioning the rear case  201 - 2  are formed on the upper wall  201 - 1  of the front case  201  placed laterally as shown in  FIG. 4 . A screw hole  201   i  for fixing the rear case  202  is formed in the tray  201   d  mounted on the lower wall  201 - 2 . 
   As shown in  FIG. 5 , the rear case  202  is made of a basket of an approximately rectangular solid placed laterally. A bottom wall  202 - 3  is made of a single plate (refer to  FIG. 3 ). Meshes of the basket are approximately rectangular. A height of a rectangular opening of the basket shown in  FIG. 5  is approximately the same as that of the front case  201 , and a width thereof is set so as to be able to arrange a connector fixing unit  202   c  for the connector  110  to be connected to the lamp  100  next to the front case  201 . 
   A slanted flange  202   a  is mounted on a lower wall  202 - 2  of the rectangular opening of the rear case  202 . This flange  202   a  has a size capable of hermetically sealing the whole opening at the end of the tray  201   d  of the front case  201 . Two engaging craws  202   b  and  202   b  for positioning and fixing the front case  201  are formed on an upper wall  202 - 1  of the rectangular opening, and a screw hole  202   e  is formed in the flange  202   a  to fix the tray  201   d  of the front case  201 . 
   As shown in  FIG. 5 , the lamp  100  is first fixed to the front case  201  of the lamp case  200  constructed as above with screws, exposing the front glass  107  (refer to  FIG. 4 ). The engaging craws  202   b  and  202   b  of the rear case  202  are engaged with the engaging members  201   h  and  201   h  of the front case  201  to cover the metal member  103  and male screw  104  projecting on the rear side of the lamp  100 , the electrode terminal  102  mounted on the mirror outer surface  106 , and the wiring fixing screws fixed to the male screw  104  and electrode terminal  102 . In this engaging state, screws are threaded into the tray  201   d  of the front case  201  to fix the rear case  202  (refer to FIG.  4 ). 
   In this case, as shown in  FIG. 3 , the connector  110  of the lamp  100  is pulled out of the rear case  202 , and as shown in  FIG. 4 , fixed to the connector fixing unit  202   c  of the rear case  202 . As shown in  FIG. 4 , the upper and lower ventilation holes  100   a  and  100   b  face the cooling-air ventilation inlet  201   a  and cooling-air ventilation outlet  201   b  of the front case  201 , and the opening  201   j  of the tray  201   d  is directed toward a light illumination direction. Replacement of the lamp  100  is usually performed in the unit of the lamp case  200 . 
   As shown in the side view of  FIG. 6 , the lamp case  200  is positioned and fixed relative to the optical unit  130  as the two positioning projections  201   f  and  201   f  on the front glass  107  side of the lamp  100  are engaged with engaging members (not shown) of the optical unit  130 . In this case, an optical axis of the lamp case  200  is made coincident with an optical axis of the subsequent optical system of the optical unit  130  such as the dichroic mirror  2   a . The optical unit  130  is connected to the lamp case  200  only optically, and no opening is formed on the mount side of the lamp case  200 . As shown in  FIGS. 3 and 6 , the ventilation fan unit  135  assembling a sirocco fan or the like is mounted above the optical unit  130 . The ventilation duct  135   a  extends from the ventilation fan unit to the position above the cooling-air ventilation inlet  201   a  of the lamp case  200 . 
     FIG. 7  is a cross sectional view of the lamp case  200  shown in  FIG. 6  taken along approximately the center of the lamp  100  and a partial ventilation duct  135   a . In a state that the lamp  100  is fixed in the lamp case  200  shown in  FIG. 7 , the ventilation hole  100   a  of the lamp  100  faces the cooling-air ventilation inlet  201   a  of the front case  201 , whereas the ventilation hole  100   b  faces the cooling-air ventilation outlet  201   b . A ventilation opening of the ventilation duct  135   a  is disposed approximately just above the cooling-air ventilation inlet  201   a  of the front case  201 , and the tray  201   d  is disposed under the cooling-air ventilation outlet  201   b.    
   Cooling-air blown from the ventilation fan unit  135  is guided from the opening of the ventilation duct  135   a  to the inside of the lamp  100  via the cooling-air ventilation inlet  201   a  of the front case  201  and the ventilation hole  100   a  of the lamp  100  to thereby cool the glass bulb  101 , the swelled portion  101   a  as the light emission region and the concave mirror  105 , as indicated by arrows in  FIG. 7 . Heated air is exhausted from the opening  201   j  of the tray  201   d  via the lower ventilation hole  100   b  of the lamp  100  and the cooling-air ventilation outlet  201   b  of the front case  201  (refer to  FIG. 4 ). 
   Heat radiated from the mirror outer surface  106  of the lamp  100  is dissipated to the inside of the housing  11  of the projector apparatus  10  shown in  FIG. 1  via a number of rectangular meshes of the basket of the rear case  202 . Heat is further expelled to outside by a cooling fan (not shown) mounted in the lower portion  13  of the housing  11 . In this embodiment, cooling-air is blown from the ventilation fan unit  135  assembling a sirocco fan or the like, and forcibly blown downward into the inside of the lamp  100 . Therefore, as compared to that cooling-air is introduced upward into the lamp  100 , a chimney effect, i.e., a temperature difference between upper and lower positions due to a rise of heated air, can be suppressed. Since the upper position of the lamp  100  and lamp case  200  is not heated to an extremely high temperature, the adverse effect of the temperature to the optical unit  130  coupled to the lamp case  130  can be mitigated. 
   Even if pieces of broken glass are scattered when the glass bulb  101  is broken, the glass pieces are accumulated on the bottom of the tray  201   d  via the lower ventilation hole  100   b  of the lamp  100  and the cooling-air ventilation outlet  201   b  of the front case  201 . Since the lamp case  200  and the optical unit  130  are spaced apart, the optical unit  130  will not be damaged with scattered glass pieces. Therefore, even if the lamp case  200  is replaced with a new one, the optical performance before replacement can be maintained. 
   The lamp case  200  constructed as above can be used in the projector apparatus  10  which uses the lamp  100  mounted in the lamp case  200  as the light source  1  shown in  FIG. 1 , synthesizes light components of, e.g., red (R), green (G) and blue (B) by using three transmission type liquid crystal panels  4   a ,  4   b  and  4   c , and magnifies and projects the synthesized light on the screen  17  via the lens. 
   According to the projector apparatus  10  and its lamp case  200  of the embodiment, the assembled lamp  100  can be forcibly and efficiently air-cooled, and it is possible to avoid an adverse effect of glass pieces to the optical system even if the lamp is broken. 
   In this embodiment, the projector apparatus of the type of a so-called three-panel liquid crystal projection television has been described in which the optical unit having three transmission type liquid crystal panels  4   a ,  4   b  and  4   c  and the light source are accommodated in the housing. The invention is not limited thereto, but it may be applied to a projector apparatus of a so-called video projector type in which an image is displayed on a screen disposed on a wall or the like. Further, the invention is not limited to the three-panel type, but obviously the invention is applicable to a single-panel projector apparatus using one transmission type liquid crystal panel. 
   The projector apparatus and its light source of the invention are not limited to the above-described embodiment, but it is obvious that various other structures may be adopted without departing from the gist of the present invention. 
   The present invention contains subject matter related to Japanese Patent Application JP2004-267400, filed in the Japanese Patent Office on Sep. 14, 2004, the entire contents of which being incorporated herein by reference.