Patent Publication Number: US-6902275-B2

Title: Light source and projector

Description:
This is a Division of application Ser. No. 09/960,374 filed Sep. 24, 2001 now U.S. Pat. No. 6,698,899. The entire disclosure of the prior application is hereby incorporated by reference herein in its entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a light source used for a projector for modulating light irradiated from a source lamp in accordance with image information to form an optical image and for enlarging and projecting the image, the light source including the source lamp, a reflector for aligning and emitting the light irradiated from the source lamp and a case for accommodating the source lamp and the reflector, and a projector provided with the source lamp. 
   2. Description of Related Art 
   Conventionally, a projector for modulating light irradiated from a source lamp in accordance with image information to form an optical image and for enlarging and projecting the image has been used. 
   Such projectors have been widely used for multimedia presentation in a meeting, scientific society, exhibition etc. Accordingly, in order to obtain vivid projected image by the projector, it is required for the light source to increase luminance thereof. 
   High-pressure mercury lamp or a metal halide lamp is used as the source lamp. When the life of the lamp expires, light-emitting tube thereof made of silica glass can be exploded to scatter the fragments around. Accordingly, the light source including the source lamp has a transparent glass plate etc. covering a light emitting surface of the reflector to prevent the fragments from scattering around even when the source lamp is exploded. 
   However, since the source lamp of the above-described light source is enclosed in a space defined by the reflector and the transparent glass plate, the temperature of the source lamp can become high so that the life of the source lamp can be shortened. 
   On the other hand, a cooling air-introducing opening may be formed on a part of the reflector and the transparent glass plate to cool the light-emitting tube. However, if an opening is formed, it is difficult to completely block the fragments from falling out when the source lamp is exploded. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a light source and a projector capable of preventing fragments from falling out to the outside even when the source lamp is exploded and capable of efficiently cooling the source lamp to lengthen the life thereof. 
   In order to achieve the above object, a light source according to an aspect of the present invention is used for a projector for modulating a light irradiated from a source lamp to form an optical image in accordance with image information and enlarging and projecting the optical image, the light source including: a source lamp; a reflector for aligning and emitting the light irradiated from the source lamp; and a case for accommodating the source lamp and the reflector, where a light-emitting surface of the reflector is covered by a light-transmissive plate and a pair of openings is formed on a contact surface of the light-transmissive plate and the reflector, the pair of openings being symmetrically disposed around an optical axis of the reflector, and where the case includes a cooling channel for introducing a cooling air to the source lamp through the pair of opening and a cooling channel shutter for shutting the cooling channel when the case is detached from the projector and for opening the cooling channel when the case is attached to the projector. 
   The above-described pair of openings may be formed by cutting a part of the light-transmissive plate, however, preferably be a recess formed by cutting a part of a distal end of the reflector in the light-emitting direction. This is because the cooling air can be flowed in a direction orthogonal with the optical axis of the reflector and around the source lamp as a heat source, so that the source lamp can be efficiently cooled. In this arrangement, the pair of openings may preferably be disposed in horizontal direction when the case is detached from the projector. 
   The case for accommodating the source lamp and the reflector refers to a case having a positioning surface for positioning the source lamp and the reflector in an optical axis direction of the irradiated light beam and in a direction orthogonal with the optical axis, which may be arranged as a molding made of plastic by injection molding etc. 
   According to the above aspect of the present invention, since the cooling channel for introducing the cooling air to the source lamp through the pair of openings is formed on the case, the source lamp can be efficiently cooled to lengthen the life of the source lamp. 
   Further, since the cooling channel shutter for shutting the cooling channel when being detached is provided, even when the light-emitting tube of the source lamp is exploded while using the projector, the fragments of the light-emitting tube do not fall outside in exchanging the light source. And since the cooling channel shutter opens the cooling channel when the case is attached to the projector, cooling efficiency of the source lamp is not impaired. When the light source is attached so that the pair of openings is horizontally disposed in detaching the case from the projector, the fragments of the light-emitting tube can be further securely prevented from falling outside in exchanging the light source. 
   In the above arrangement, the cooling channel shutter may preferably include a lid member rotatably supported to the case for shutting the opening formed on the case and a biasing member for biasing the lid member in rotary direction, or alternatively, may preferably include a lid member slidably supported by the case for shutting an opening formed on the case and a biasing member for biasing the lid member in slide direction thereof, which may be provided on one of, or both of air-introducing opening and air-exhausting opening of the cooling channel formed in the case. 
   Since the cooling channel shutter is made of a lid member and a biasing member, the cooling channel shutter can be provided on the case with a simple arrangement, so that the light source can be easily produced. 
   In the above, the case may preferably be provided with a duct for guiding an air from an outside of the case to the cooling channel and/or from the cooling channel to the outside of the case. 
   By forming the duct to the case, introduction of cooling air from outside the case and discharge of the after-cooling air to the outside of the case can be conducted at a position corresponding to the cooling channel in the projector, so that cooling efficiency of the light source can be further enhanced. 
   Further, a dust filter may preferably be provided on the pair of openings. 
   The dust filter may only be provided to the air-introducing opening or to the air-exhausting opening, or alternatively to both of the pair of openings. 
   Since the dust filter is provided, the fragments can be securely prevented from falling out of the case even when the light-emitting tube of the source lamp is exploded. Further, when the dust filter is provided to the air-introducing opening, the dust invasion in accordance with introduction of the cooling air can be prevented, thus avoiding decrease in luminance when the light-emitting tube gets dirty. 
   A projector according to the present invention includes the above-described light source, which can obtain the same function and effects as in the above. 
   In the above projector, a duct having an end inserted to the cooling channel shutter while being attached to the light source for introducing the cooling air into the light source may preferably be provided. 
   By having such duct, the cooling air in the projector can be securely introduced into the light source, thereby further enhancing cooling efficiency of the light source and lengthening the life of the light source. 
   The duct may preferably include a fan on the base end thereof for transferring the cooling air, or when an exhaust duct for discharging the air having cooled the inside of the light source is provided, the base end of the duct may preferably be connected to the exhaust duct. 
   Since the fan is provided to the duct or the duct is connected to the exhaust duct, the cooling air can be forcibly transferred from the duct to the cooling channel, so that the circulation of the cooling air can be enhanced to improve the cooing efficiency of the light source. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an entire perspective view showing a projector according to an embodiment of the present invention seen from above; 
       FIG. 2  is an entire perspective view of the projector according to the aforesaid embodiment seen from below; 
       FIG. 3  is an entire perspective view of the projector according to the aforesaid embodiment seen from below; 
       FIG. 4  is an entire perspective view showing an inside of the projector of the aforesaid embodiment; 
       FIG. 5  is a plan view schematically showing respective optical systems of projector of the aforesaid embodiments; 
       FIG. 6  is a perspective view showing components of the projector of the aforesaid embodiment; 
       FIG. 7  is a perspective view showing a light source of the aforesaid embodiment; 
       FIG. 8  is an exploded perspective view showing a light source of the aforesaid embodiment; 
       FIG. 9  is a perspective view showing a light source of the aforesaid embodiment; 
       FIG. 10  is an illustration showing a light source protector of the aforesaid embodiment; 
     FIGS.  11 (A) and  11 (B) are schematic views illustrating opening and closing first cooling channel shutter of the aforesaid embodiment; 
     FIGS.  12 (A) and  12 (B) are schematic views illustrating opening and closing second cooling channel shutter of the aforesaid embodiment; 
       FIG. 13  is a perspective view showing cooling mechanism of the light source of the aforesaid embodiment; and 
       FIG. 14  is a perspective view showing a cooling mechanism of a light source according to a modification of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S) 
   An embodiment of the present invention will be described below with reference to attached drawings. 
   [1. Primary Arrangement of Projector] 
     FIG. 1  is an entire perspective view showing a projector  1  according to the present embodiment seen from above,  FIGS. 2 and 3  are entire perspective views showing the projector  1  and  FIG. 4  is a perspective view showing an inside of the projector  1  seen from below. 
   A projector  1  separates a light beam irradiated from a light source into three primary colors of red (R), green (G) and blue (B), modulates the light beams of respective colors in accordance with image information through the liquid crystal panel as an optical modulator constituting an electric optical device and synthesizes the modulated light beams of respective colors by a cross dichroic prism to enlarge and display the beam on a projecting surface through a projection lens  46 . Though respective components are accommodated in an exterior case  2 , the projection lens  46  is protrudable and retractable from the exterior case  2  by a zoom mechanism thereof as necessary. 
   In  FIGS. 1  to  4 , the projector  1  has the exterior case  2  as a casing, a power supply unit  3  accommodated in the exterior case  2 , and an optical unit  4  of planarly L-shape disposed in the exterior case  2 , the entirety of the projector  1  being approximate rectangular solid. 
   The exterior case  2  includes a sheet-metal upper case  21  covering upper side of the device, a lower case  23  made of die casting such as magnesium constituting the bottom of the device, and a middle case  22  made of aluminum or bent steel plate disposed between the upper case  21  and the lower case  23  to cover the sides of the device. 
   The upper case  21  is formed of an upper portion  211  and a side portion  212  disposed around the upper portion  211 , which is, for instance, shaped by a press using a die. A circular hole  211 D corresponding to a lens attachment frame  24  for attaching the projection lens  46  is provided to a front portion  211 A side of the side portion  212 , the neighborhood of the circular hole  211 D being curved inwardly by drawing. A notch  211 C (see  FIG. 3 ) is formed on a side orthogonal with the front portion  211 A of the side portion  212 . 
   A manipulation switch  2 B for adjusting image quality of the projector  1  is provided to the projection lens  46  side of the upper portion  211  of the upper case  21 . A number of holes  2 C for speaker is provided on both sides of the manipulation switch  2 B. 
   The middle case  22  is, as described above, formed by bending aluminum plates etc., which includes a fist case member  22 A and a second case member  22 B disposed on both sides of the projection lens  46 , and a third case member at the back of the first case member  22 A. An interface exposed member  22 D exposing various connectors for the interface provided on an interface substrate  92  disposed inside the middle case  22  is disposed and connected and an openable and closable lamp cover  22 E is provided between the second case member  22 B and the third case member  22 C. 
   The respective case members  22 A,  22 B and  22 C have a configuration capable of combined with the upper case  21  and the lower case  23  by bending the aluminum plates having a predetermined configuration blanked by a press or a machining center. 
   An opening (not shown) corresponding to the lens attachment frame  24  is formed between a front  221 A formed on a front side of the first case member  22 A and the second case member  22 B. Another opening (not shown) is formed on the front  221 A side of the second case member  22 B, which opposes an exhaust hole  24 A formed on the lens attachment frame  24 . 
   The lens attachment frame  24  is attached to the middle case  22  to form the middle case  22 . Incidentally, a cover  240  made of, for instance, plastic, is attached around the exhaust hole  24 A. 
   Handle openings  221 B extending from the lower case  23  toward the upper case  21  by a predetermined distance spaced apart with each other are provided to the second case member  22 B. A handle  80  used in carrying the projector  1  is attached to the openings  221 B. 
   As shown in  FIG. 3 , the lamp cover  22 E has a knob  81  such as a screw on the second case member  22 B side and is engaged to the peripheral end of the third case member  22 C. The knob  81  is screwed to a nut (not shown) formed on the second case member  22 B through an E ring. When the knob  81  is rotated to release screwing with the nut, the knob  81  projects to the outside from the lamp cover  22 E by the amount being screwed. When the knob  81  is held to slide the lamp cover  22 E along the side of the projector  1 , the lamp cover  22 E can be detached. Incidentally, since the knob  81  is supported by the E ring, the knob  81  is not detached from the lamp cover  22 E even after releasing to screw with the nut. 
   As mentioned above, the lower case  23  is a die-casting of magnesium etc., where an approximately rectangular bottom portion  231  and a side portion  232  around the bottom portion are integrally formed. A reinforcing rib etc. is formed at a predetermined location inside the lower case  23 , thereby securing strength of the entire lower case  23 . 
   A height position adjuster  7  for adjusting inclination of the entire projector  1  to adjust position of the projected image is provided on both corners of front side of the bottom portion  231  of the lower case  23 . On the other hand, a resin-made foot member  6  ( FIG. 2 ) is fitted to the rear center of the bottom portion  231 . Incidentally, the height position adjuster  7  advances and retracts in protruding direction by rotating the dial portion or manipulating lever thereof, the advancement retraction being adjusted to change height and inclination of the displayed screen. 
   A fan cover  235  is attached to the bottom portion  231  of the lower case  23 . A circular hole  232 D corresponding to the lens attachment frame  24  is provided to a front portion  232 A of the lower case  23 . 
   An intake hole  2 A for introducing cooling air to the inside, an exhaust hole  24 A for exhausting the air after cooling, the manipulation switch  2 B, the multiple holes  2 C corresponding to positions of the speaker and the handle opening  221 B are provided to the exterior case  2 . Incidentally, the cooling air is introduced to the inside from the handle opening  221 B. 
   As shown in  FIG. 4 , the power unit  3  is composed of a power supply (not shown) disposed on the bottom side in the exterior case  2  and a lamp driving circuit  101  disposed at the back of the power supply. The power supply supplies the electric power supplied through the power cable to the lamp driving circuit  101  and a driver board (not shown), which includes an inlet connector  33  for the power cable to be plugged (FIG.  4 ), an aluminum frame surrounding the power supply and a power circuit. 
   The lamp driving circuit supplies the electric power to a source lamp  411  ( FIG. 5 ) as a light source of the optical unit  4 . An axial flow intake fan  70  as a cooling fan for introducing the air into the inside of the projector  1  is provided to the front side of the lamp driving circuit  101 . 
   As shown in  FIG. 5 , the optical unit optically processes the light beam irradiated from the source lamp  411  to form an optical image corresponding to the image information, which includes an integrator illuminating optical system  41 , a color separating optical system  42 , a relay optical system  43 , an electric optical device  44 , a cross dichroic prism  45  as a color synthesizing optical system and a projection lens  46  as a projection optical system. 
   [2. Detailed Arrangement of Optical System] 
   In  FIG. 5 , the integrator illuminating optical system  41  is an optical system for substantially uniformly illuminating the image formation areas of the three liquid crystal panels  441  (respectively represented as liquid crystal panels  441 R,  441 G and  441 B for each color light of red, green and blue), which includes a light source  413 , a UV filter  418 , a first lens array  414  as a beam splitter, a second lens array  416 , a polarization converter  415 , a superposing lens  419  and a reflection mirror  424 . 
   The light source  413  constituting the integrator illuminating optical system  41  has the source lamp  411  as a radial light source for emitting radial light beam and a reflector  412  for reflecting the radial light emitted from the source lamp  411 . A halogen lamp, a metal halide lamp, or a high-pressure mercury lamp is often used as the source lamp  411 . A parabolic mirror is used as the reflector  412 , however, an ellipsoidal mirror and a parallelizing lens (concave lens) may be used. 
   The first lens array  414  has a matrix arrangement of lenses  414 A having substantially rectangular profile viewed from optical axis direction. The respective lenses  414 A split the beam emitted from the source lamp  411  to pass the UV filter  418  into a plurality of partial light beams. The profile of the respective lenses  414 A is approximately similar to the configuration of the image formation area of the liquid crystal panel  441 . For instance, when the aspect ratio (ratio of horizontal and vertical dimensions) of the liquid crystal panels  441  is 4:3, the aspect ratio of the respective lenses is also set as 4:3. 
   The second lens array  416  has approximately the same arrangement as the first lens array  414 , where the lenses  416 A is disposed in matrix. The second lens array  416  focuses the image from the respective lenses  414 A of the first lens array  414  onto the liquid crystal panel  441  as well as the superposing lens  419 . 
   The polarization converter  415  is disposed between the second lens array  416  and the superposing lens  419  for converting the light from the second lens array  416  to a single polarized light in order to enhance utilization efficiency of the light in the electric optical device  44 . 
   Specifically, the respective partial light converted into single polarized light by the polarization converter  415  is substantially superposed on the liquid crystal panels  441 R,  441 G and  441 B of the electric optical device  44  by the superposing lens  419 . Since the projector  1  (the electric optical device  44 ) of the present embodiment using a liquid crystal panel  441  for modulating polarized light can use only single polarized light, approximately half of the light from the source lamp  411  emitting random polarization light of other type cannot be used. 
   Accordingly, by using the polarization converter  415 , all of the emitted light from the source lamp  411  is converted into single polarized light to enhance utilization efficiency of the light in the electric optical device  44 . Incidentally, such polarization converter  415  is disclosed in, for instance, Japanese Patent Laid-Open publication No. Hei 8-304739. 
   The color separating optical system  42  has two dichroic mirrors  421  and  422  and a reflection mirror  423 , where the mirrors  421  and  422  separates the plurality of partial light beam irradiated from the integrator illuminating optical system  41  into three color lights of red, green and blue. 
   The relay optical system  43  includes an incident-side lens  431 , a relay lens  433  and a reflection mirrors  432  and  434 , which introduces blues light of the color lights separated by the color separating optical system  42  into the liquid crystal panel  441 B. 
   At this time, the blue color light component and the green light component of the light beam irradiated from the integrator illuminating optical system  41  is reflected by the dichroic mirror  421  of the color separating optical system  42  and the red color light component transmits through the dichroic mirror  421 . The red color light transmitted through the dichroic mirror  421  is reflected by the reflection mirror  423 , which reaches to the liquid crystal panel  441 R for red-color through a field lens  417 . The field lens  417  converts the respective partial light beam emitted from the second lens array  416  into a light beam parallel to central axis (main beam). The field lenses  417  provided in front of the other liquid crystal panels  441 G and  441 B function in the same manner. 
   In the blue light and the green light reflected by the dichroic mirror  421 , the green light is reflected by the dichroic mirror  422  to reach the liquid crystal panel  441 B for green color through the field lens  417 . On the other hand, the blue color transmits through the dichroic mirror  422  to pass the relay optical system  43  and reach the liquid crystal panel  441 B for blue color through the field lens  417 . Incidentally, the relay optical system  43  is used for the blue color in order to prevent decrease in utilization efficiency of light on account of light diffusion because the length of the optical path of the blue color light is longer than the length of the optical path of the other color lights, in other words, in order to directly transmit the partial light beam incident on the incident-side lens  431  to the field lens  417 . 
   The electric optical device  44  has the liquid crystal panels  441 R,  441 G and  441 B as three optical modulators which, for instance, use a polysilicon TFT as switching element. The color lights separated by the color-separating optical systems  42  is modulated by the three crystal panels  441 R,  441 G and  441 B in accordance with image information to form optical image. 
   The cross dichroic prism  45  synthesizes the images modulated for respective color lights irradiated from the three liquid crystal panels  441 R,  441 G and  441 B to form a color image. Incidentally, a dielectric multilayer film for reflecting red light and another dielectric multiplayer film for reflecting blue light are formed on the prism  45  along boundaries of the four right-angled prisms, the dielectric multilayers synthesizing three color lights. The color image synthesized by the prism  45  is irradiated from the projection lens  46  and is enlarged and projected on a screen. 
   The above-described respective optical systems  41  to  45  are disposed on a lower side of a main board  90  covered with a shield plate  91  as shown in  FIGS. 4 and 6  and is accommodated in a inner case  47  ( FIG. 6 ) as an optical component casing of synthetic resin. Specifically, the lower inner case  47  is provided with a groove for slidably fitting the respective optical components  414  to  419 ,  421  to  424  and  431  to  434  from upper direction as well as a light source protector  471  for covering the light source  413 . 
   A head portion  49  is formed on the light-irradiating side of the lower inner case  47 . The prism  45  attached with the liquid crystal panels  441 R,  441 G and  441 B is fixed to one end of the head portion  49  and the projection lens  46  is fixed to a flange along semi-cylindrical portion of the other end. 
   [3. Structure of Light Source] 
   As shown in  FIGS. 7 and 8 , the light source  413  has a lamp body  410  and a case  300  for accommodating the lamp body  410  and is attachable and detachable to the light source protector  471  of the projector  1 . 
   The lamp body  410  has the source lamp  411  and the reflector  412  for aligning and emitting the light irradiated from the source lamp  411 . 
   The light-emitting surface of the reflector  412  is covered with a light-transmissive plate  301  such as a glass plate. A pair of openings  302  symmetrically disposed around the optical axis of the reflector  412  is formed on the contact surface of the light-transmissive plate  301  and the reflector  412 . The pair of openings  302  are respectively composed of a recess  303  formed on the distal portion in the light-emitting direction of the reflector  412 . A dust filter (not shown) is respectively provided on the pair of openings  302 . Accordingly, a cooling channel  340  is formed in the lamp body  410  to cool the source lamp  411 . 
   The case  300  has a positioning surface for locating the source lamp  411  and the reflector  412  in the optical axis direction of the emitted light and in a direction orthogonal with the optical axis, which further includes a case body  310  with a part thereof being opened, a first lid member  320  and a second lid member  330  for shutting the opening of the case body  310 , the cooling channel  340  for introducing cooling air to the source lamp  411  through the pair of openings  302 , and a first cooling channel shutter  350  and a second cooling channel shutter  360  for shutting the cooling channel  340  when being detached from the projector  1  and for opening the cooling channel  340  when being attached to the projector  1 . 
   The case body  310  accommodates the lamp body  410 , which includes a bottom portion  311  for the lamp body  410  to be mounted and a side portion  313  perpendicularly rising from the periphery of the bottom portion  311  and has approximate C-shape cross section. 
   An opening  314  for the light-transmissive plate  301  to be exposed is formed on a part of the side portion  313 . 
   When the lamp body  410  is accommodated in the case body  310 , the periphery of the reflector  412  is brought into contact with the side portion  313  formed with the opening  314  and the periphery of the reflector  412  and the side portion  313  are held from outside by a clip  370 , so that the lamp body  410  is secured to the case body  310 . 
   An opening  312  for in communication with the inside and the outside of the case body  310  is formed on the bottom portion  311  at a position corresponding to the position to which the below-described first cooling channel shutter  350  is attached. 
   The first lid member  320  directly shuts the opening of the case body  310 , which includes a lid body  321  attached to a side opposite to the bottom portion  311  and an extension  326  extending from the end portion of the lid body  321  toward the case body  310  and has an approximate C-shape cross section. The lid body  321  is formed in approximate trapezoid plane, and has a square pillar guide plate  322  for guiding the cooling air on the upper side thereof. A square opening  323  is formed adjacent to a side of the lid body  321  (near side in FIG.  8 ). A frame  324  having approximately the same size as the opening  323  is provided on a position corresponding to the opening  323 . A mesh filter  325  is interposed between the frame  324  and the lid body  321 . 
   In the two extensions  326 , the right (in  FIG. 8 ) extension  326  has a recess  327  having an opening directed upward on a central side portion thereof. 
   The second lid member  330  covers the first lid member  320 , which includes a cover  331  for covering the lid body  321  of the first lid member  320  and an extension  336  extending toward the lid body  321  and is secured to the first lid member  320  by a screw  304 . 
   A side of the second lid member  330  opposite to the recess  327  has a recess  332  formed in a C-shape and dented downward and a groove  333  on the opposing sides of the inner side. The recess  332  is arranged to be an opening when the second lid member  330  is superposed on the first lid member  320 . 
   The second lid member  330  floats in upper direction for the height dimension of the guide plate  322  in being attached to the first lid member  320 . In other words, a gap is formed between the first lid member  320  and the second lid member  330 . Accordingly, the air in the cooling channel  340  in the case  300  and the air outside the case  300  can be exchanged by the gap. Therefore, the gap is a duct for guiding the air from the outside of the case  300  to the cooling channel  340  and/or from the cooling channel  340  to the outside of the case  300 . 
   The first cooling channel shutter  350  is rotatably supported to the case body  310 , which includes a lid member  351  formed on the case body  310  for shutting the opening  312  and a coil spring  356  as a biasing member for biasing the lid member  351  in rotary direction. 
   The lid member  351  is formed in a box-shape, and a pair of claws  352  projecting toward the case body  310  is formed on both side peripheries thereof. 
   A recess  353  for a below-described first projection  475  to be inserted is formed between the claw  352  and the side surface. 
   Accordingly, as shown in  FIG. 9 , when the recess  353  is pushed in a direction away from the case body  310  for instance, the lid member  351  is opened, so that the cooling air is introduced into or discharged from the opening  312 . On the other hand, when a hand is released from the pushed recess  353 , the lid member  351  automatically shuts the opening  312  by virtue of the biasing force of the coil spring  356 . 
   The second cooling channel shutter  360  is slidably supported to the case body  310 , which includes a lid member  361  for shutting the opening formed by the recess  332  of the second lid member  330  and a coil spring  366  as a biasing member for biasing the lid member  361  in a slide direction. 
   The lid member  361  has a plate-shaped contact portion  362  to be in contact with a horizontal portion of the recess  332  and a periphery fitted to the groove  333  and includes a slide portion  363  orthogonal with the backside of the contact portion  362  for sliding along the case body  310  and a claw  364  to be in contact with the distal end of the extension  336 , which is shaped in approximate T-shape cross section and approximate square front side. 
   The coil spring  366  has one end attached to the lid member  361  and the other end inserted and secured to the recess  927  formed on the extension  326  of the first lid member  320 . 
   Accordingly, as shown in  FIG. 9 , when the claw  364  is pushed toward the case body  310 , the lid member  361  is opened and the opening between the first lid member  361  and the second lid member  330  emerges to discharge or introduce the cooling air. On the other hand, when the hand is released from the pushed claw  364 , the lid member  361  automatically shuts the opening by the biasing force of the coil spring  366 . 
   Such light source  413  is attachable and detachable relative to the light source protector  471 , as shown in FIG.  10 . 
   The light source protector  471  has an accommodating portion  472  having approximately the same shape as the light source  413  thereinside, and is formed in a box-shape with a side opposite to the projection lens  46  being opened. 
   In  FIG. 10 , the light source  413  is accommodated in the accommodating portion  472  from the second lid member  330  with the opening  314  of the case body  310  disposed on the right side. In other words, the bottom portion  311  of the case body  310  is exposed to the outside. Further, the light source  413  is accommodated in the accommodating portion  472  while the opening  314  of the case body  310  is disposed on the right side and is detached in this condition so that the pair of openings  302  formed on the lamp body  410  is horizontally disposed. 
   A pair of first projections  475  is formed on the periphery of the opening of the inner case  47 , the first projections  475  being inserted to the recess  353  of the first cooling channel shutter  350  and pushing up the recess  353  when the light source  413  is fitted to the accommodating portion  472 . 
   Further, a pair of second projections  476  being in contact with the claw  364  of the second cooling channel shutter  360  and pushing up the claw  364  when the light source  413  is fitted to the accommodating portion  472  and an opening  477  being in communication with an air intake of a sirocco fan (not shown) as a centrifugal fan disposed below the bottom surface  473  are formed on the bottom surface  473  of the accommodating portion  472 . 
   The opening  477  opposes an opening between the first lid member  320  and the second lid member  330  when the light source  413  is accommodated in the accommodating portion  472 . The opening  474  formed in front of the opening  477  is an opening for the air around the outside of the light source  413  to be flowed in, which can take in substantially low temperature air as compared to the temperature inside the reflector  412 . 
   Accordingly, when the light source  413  is accommodated in the accommodating portion  472  (i.e. attached to the projector  1 ), the first cooling channel shutter  350  is automatically opened by the first projection  475  as shown in FIG.  11 (A) to open the cooling channel  340  in the case  300 . On the contrary, when the light source  413  is detached from the accommodating portion  472  (detached from the projector  1 ), the first cooling channel shutter  350  automatically shuts the cooling channel  340  by the biasing force of the coil spring  356  as shown in FIG.  11 (B). 
   In the same manner, the second cooling channel shutter  360  is automatically opened by the second projection  476  when the light source  413  is accommodated in the accommodating portion  472  (i.e. attached to the projector  1 ) as shown in FIG.  12 (A) to open the cooling channel  340  in the case  300 . On the contrary, when the light source  413  is detached from the accommodating portion  472  (i.e. detached from the projector  1 ), the second cooling channel shutter  360  automatically shuts the cooling channel  340  by the biasing force of the coil spring  366  as shown in FIG.  12 (B). 
   On the other hand, as shown in  FIG. 13 , the projector  1  has a square pipe duct  381  having an end inserted to the first cooling channel shutter  350  for introducing the cooling air into the light source  413  attached in the accommodating portion  472 . 
   A sirocco fan  382  as a centrifugal fan for transferring the cooling air is provided on the base end of the duct  381  (opposite to the first cooling channel shutter  350 ). 
   Accordingly, the cooling air in the light source  413  provided with the sirocco fan  382  and the duct  381  flows through the cooling channel  340  from the first cooling channel shutter  350  to the second cooling channel shutter  360 . In other words, the opening  312  of the case body  310  is an air-introducing opening and the opening opened and closed by the second cooling channel shutter  360  is an air-exhausting opening. 
   Therefore, the cooling air inhaled into the inside of the projector  1  from the above-described intake hole  2 A and the handle opening  221 B can be securely introduced to the source lamp  411  of the light source  413 . The air having cooled the inside of the light source  413  passes the opening  474  formed on the bottom surface  473  of the accommodating portion  472 , is inhaled by the sirocco fan and is discharged to the outside of the projector  1  through the exhaust duct  390  connected to the sirocco fan. 
   According to the present embodiment, following effects can be obtained. 
   Since the pair of openings  302  is constructed by the recess  303  formed by cutting a part of the peripheral end of the reflector  412  in the light-emitting direction, the cooling air can be flowed in a direction orthogonal with the optical axis of the reflector  412  toward around the source lamp  411  as a heat source, thereby efficiently cooling the source lamp  411 . 
   Since the cooling channel  340  for introducing the cooling air to the source lamp  411  via the pair of openings  302  is provided to the case  300 , the source lamp  411  can be efficiently cooled to lengthen the life of the source lamp  411 . 
   Since the first and the second cooling channel shutters  350  and  360  for shutting the cooling channel  340  when being detached from the projector  1  are provided, even when the light-emitting tube of the source lamp  411  is exploded while using the projector  1 , the fragments of the light-emitting tube is not fallen outside in exchanging the light source  413 . And since the first and the second cooling channel shutters  350  and  360  open the cooling channel  340  in attaching to the projector  1 , the cooling efficiency of the source lamp  411  is not impaired. Further, since the light source  413  is attached so that the pair of openings  302  is disposed in horizontal direction when the light source  413  is detached from the projector  1 , the fragments of the light-emitting tube of the source lamp  411  can be further securely prevented from falling out to the outside in exchanging the light source  413 . 
   Since the first and the second cooling channel shutters  350  and  360  are respectively constructed by the lid members  351  and  361  and the coil springs  356  and  366 , the shutter for the cooling channel  340  can be provided to the case  300  with a simple structure, thereby facilitating production of the light source  413 . 
   Since a duct is formed between the first lid member  320  and the second lid member  330 , the introduction of the cooling air from the outside of the case  300  and the discharge of the after-cooling air toward the outside of the case  300  can be conducted at a position corresponding to the cooling channel  340  in the projector  1 , thereby further enhancing the cooling efficiency of the light source  413 . 
   Since a dust filter is respectively provided to the pair of openings  302 , even when the light-emitting tube of the source lamp  411  is exploded, the fragments can be prevented from falling out to the outside of the case  300 . Further, since the dust filter is provided to the air-introducing opening  302 , the invasion of dust into the light source  413  in accordance with introducing the cooling air can be prevented, thereby preventing decrease in luminance caused when the light-emitting tube gets dirty. 
   In the projector  1  attached with the light source  413 , since the duct  381  for introducing the cooling air to the light source  413  is provided, the cooling air in the projector  1  can be securely guided to the inside of the light source  413 , thereby further enhancing the cooling efficiency of the light source  413  to lengthen the life of the light source  413 . 
   Since the sirocco fan  382  is provided to the duct  381 , the cooling air can be forcibly transferred from the duct  381  to the cooling channel  340 , thereby facilitating circulation of the cooling air to further enhance the cooling efficiency of the light source  413 . 
   Incidentally, the scope of the present invention is not restricted to the above-described embodiment but includes other arrangement as long as an object of the present invention can be achieved, which includes following modifications. 
   For instance, though a cooling fan is provided in the aforesaid embodiment, such arrangement is not limiting but, as shown in  FIG. 14 , a hole may be formed on a part of the exhaust duct  390  and an exhaust duct  383  for discharging the air having cooled the inside of the device toward the outside of the device may be connected to the hole. In this case, the air inside the exhaust duct  390  is a mixture of the air inside the reflector and the air outside the reflector of substantially low temperature, which is lower than the temperature inside the reflector, so that sufficient cooling effect can be obtained. 
   Though the cooling air inhaled by the cooling fan is forcibly transferred from the duct to the cooing channel  340  and is discharged by the sirocco fan to the outside of the projector, the air inhaled by the sirocco fan may be forcibly transferred to the cooling channel  340  and discharged to the outside of the projector by the cooling fan. Accordingly, the cooling air can flow through the cooling channel  340  from the second cooling channel shutter  350  to the first cooling channel shutter  360 . 
   Though a duct is provided in the aforesaid embodiment, the duct may be omitted when sufficient cooling air can be introduced into the light source by an opening opened and closed by the first cooling channel shutter  350 . 
   Though the dust filter is provided respectively on the pair of openings in the aforesaid embodiment, the dust filter may be provided only to the air-introducing opening or air-discharging opening of the pair of openings. 
   Though a duct is formed between the first lid member  320  and the second lid member  330  in the aforesaid embodiment, the duct may be omitted when introduction of the cooling air from the outside of the case  300  and discharge of the after-cooling air toward the outside of the case  300  can be efficiently conducted. 
   Though the first and the second cooling channel shutters are provided with the lid member and the coil spring, the coil spring may be omitted when the lid member can be opened and closed by the light source protector side, and the configuration and arrangement may be determined in implementing the present invention. 
   Though two-types of cooling channel shutters are used in the aforesaid embodiment, only the first cooling channel shutter  350  may be used or only the second cooling channel shutter  360  may be used, which can be determined according to the configuration and arrangement of the light source protector. 
   Though the pair of openings is disposed in horizontal direction when being detached from the projector in the aforesaid embodiment, the pair of openings may be disposed in perpendicular direction. 
   Though the pair of openings is constructed of a recess  303  formed by cutting a part of peripheral end of the reflector  412  in the light-emitting direction in the aforesaid embodiment, the pair of opening may be formed by, for instance, cutting a part of the light-transmissive plate. 
   The projector of the present invention is not limited to those having a crystal liquid panel as an optical modulator, but may be those having an optical modulator of plasma element and micro mirror, having a reflective optical modulator for reflecting and modulating to emit the incident light, and single-plate type, double-plate type and rear type. In other words, any arrangement is possible in implementing the present invention as long as the light beam irradiated from the source lamp is modulated in accordance with image information to form an optical image and the optical image is enlarged and projected by the projector.