Patent Document

[0001]    This application claims priority under 35 U.S.C. Section 119 of Japanese Patent Application No.2010-111109 filed May 13, 2010, entitled “PROJECTION DISPLAY DEVICE”. The disclosure of the above application is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a projection display device that modulates light from a light source by an imager, and enlarges and projects the modulated light on a projection plane. The present invention relates particularly to a projection display device that forms an image on an imager as an intermediate image between a projection lens and a mirror, and enlarges and projects the intermediate image by the mirror. 
         [0004]    2. Disclosure of Related Art 
         [0005]    Conventionally, in a projection display device such as a liquid crystal projector (hereinafter, called “projector”), expanding a projection angle of light from a projection optical system has been promoted for shortening a distance between a screen and the projector. In addition to expanding the projection angle, there is proposed a projector configured to perform slant projection such that projection light emitted from the projector is obliquely projected onto a screen. 
         [0006]    In the thus configured projector, a projection lens unit and a reflection mirror can be used as a projection optical system, for example. In this configuration, an image on an imager is formed as an intermediate image between the projection lens unit and the reflection mirror, and the intermediate image is enlarged and projected by the reflection mirror. This realizes a shorter projection distance. 
         [0007]    In addition, a control circuit board for driving and controlling the projector needs a relatively wide area. This may cause the projector body to be made large in size depending on how to dispose the control circuit board. 
         [0008]    In general, the control circuit board is disposed within a main body cabinet above an optical engine formed by an imager or the like. However, the projector performing slant projection has a projection port oriented in a slant upward direction on a top surface of the main body cabinet, and light turned back by the reflection mirror travels to the screen through the projection port. In this arrangement, if the top surface of the main body cabinet projects upward near a front side of the projection port, the top surface may block out the projection light. Accordingly, the control circuit board cannot be disposed so close to the reflection mirror. 
         [0009]    In addition, if the control circuit board is disposed relatively distant from the reflection mirror in a direction of projection, the main body cabinet (projector body) is prone to become larger in dimension in the direction of projection. If the projector is larger in dimension in the direction of projection, a throw distance (from the projection port to a screen) becomes longer when the projector is made closest to the screen. Accordingly, if the size of the projection screen is adjusted by moving the projector closer to or distant from the screen, it is not possible to reduce a minimum size of the projection screen, which narrows an adjustment range of projection screen size. 
         [0010]    As described above, the projector configured to perform slant projection is subject to various restrictions in shape and size of the projector body. Accordingly, it is necessary to dispose the control circuit board in a position so as to prevent the projector body from being larger in size, with due considerations to these restrictions. 
       SUMMARY OF THE INVENTION 
       [0011]    A projection display device in a main aspect of the present invention includes: a light source; an imager portion which modulates light from the light source; a projection portion which enlarges and projects the light modulated by the imager portion; a control circuit; and a main body cabinet in which the light source, the imager portion, the projection portion, and the control circuit portion are disposed. In this arrangement, the projection portion is formed by a projection lens portion into which the light from the imager portion is entered and a mirror portion which reflects the light having passed through the projection lens portion and lets the light travel toward a projection plane. The mirror portion is disposed so as to be shifted from an optical axis of the projection lens portion in a direction opposite to a direction in which the incident light from the projection lens portion is turned back. In addition, the control circuit portion is disposed in a space which is produced between the projection lens portion and the main body cabinet by a position gap between the projection lens portion and the mirror portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The foregoing and other objects and novel features of the present invention will be more fully understood from the following description of a preferred embodiment when reference is made to the accompanying drawings. 
           [0013]      FIGS. 1A and 1B  are diagrams (perspective views) showing an outer configuration of a projector in an embodiment of the present invention. 
           [0014]      FIG. 2  is a diagram (bottom view) showing an outer configuration of the projector in the embodiment. 
           [0015]      FIG. 3  is a diagram showing an inner structure of the projector in the embodiment. 
           [0016]      FIG. 4  is a diagram showing schematically a configuration of the projection optical unit in the embodiment. 
           [0017]      FIG. 5A and 5B  are diagrams showing a configuration of a control circuit unit in the embodiment. 
           [0018]      FIG. 6  is a diagram of a configuration of the control circuit unit in the embodiment. 
           [0019]      FIG. 7  is a diagram showing a configuration of an optical unit in the embodiment. 
           [0020]      FIG. 8  is a diagram showing a main body cabinet with the optical unit not yet attached in the embodiment. 
           [0021]      FIG. 9  is a diagram for describing a projection mode and an effect thereof of the projector in the embodiment. 
           [0022]    However, the drawings are only for illustration and do not limit the scope of the present invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0023]    In the following, an embodiment of the invention is described referring to the drawings. 
         [0024]    In this embodiment, a lamp unit  14  is equivalent to a “light source” recited in the claims; an imager unit  15  is equivalent to an “imager portion” recited in the claims; a projection optical unit  17  is equivalent to a “projection portion” recited in the claims; a projection lens unit  101  is equivalent to a “projection lens portion” recited in the claims; a reflection mirror  102  is equivalent to a “mirror portion” recited in the claims; a main control board  210  and an extension interface board  220  are equivalent to a “circuit board” recited in the claims; a terminal panel  240  is equivalent to a “terminal portion” recited in the claims; a holder  250  is equivalent to a “holding member” recited in the claims. The foregoing correspondence in description between the claims and this embodiment are merely examples, and do not limit the claims to this embodiment. 
         [0025]      FIGS. 1A ,  1 B and  FIG. 2  are diagrams showing an external construction of a projector embodying the invention.  FIG. 1A  is a perspective view of the projector when viewed from a front side, and  FIG. 1B  is a perspective view of the projector when viewed from a rear side.  FIG. 2  is a bottom view of the projector. To simplify the description, arrows respectively indicating forward, rearward, leftward, and rightward directions are depicted in  FIGS. 1A ,  1 B and  FIG. 2 . Hereinafter, the arrows indicating forward, rearward, leftward, and rightward directions are depicted in the same manner as above in the other drawings, as necessary. 
         [0026]    The projector of the embodiment is a so-called short focus projector. Referring to  FIGS. 1A and 1B , the projector is provided with a main body cabinet  1  having a substantially rectangular parallelepiped shape. The main body cabinet  1  is constituted of a lower cabinet  2 , and an upper cabinet  3  which is placed on the lower cabinet  2  from above. 
         [0027]    A top surface of the main body cabinet  1  is formed with a first slope  1   a  inclined downward and rearward, and a second slope  1   b  continuing from the first slope  1   a  and inclined upward and rearward. The second slope  1   b  faces obliquely upward and forward, and a projection port  4  is formed in the second slope  1   b.  Image light emitted obliquely upward and forward through the projection port  4  is enlarged and projected onto a screen disposed in front of the projector. 
         [0028]    Further, the top surface of the main body cabinet  1  is formed with a lamp cover  5 . The top surface of the main body cabinet  1  is formed with a lamp opening for use in exchanging a lamp unit, and a filter opening for use in exchanging a filter disposed in a fan unit for cooling the lamp unit. The lamp cover  5  is a cover for covering the lamp opening and the filter opening. Further, the top surface of the main body cabinet  1  is provided with an operation portion  6  constituted of a plurality of operation keys. 
         [0029]    A terminal port portion  7  is formed in a right surface of the main body cabinet  1 . A terminal panel  240  having various terminals such as AV terminals is attached to the terminal port portion  7 . The terminal panel  240  constitutes a part of a control circuit unit to be described later. Audio Visual (AV) signals such as an image signal and an audio signal are inputted and outputted to and from the projector through the AV terminals. Further, an air inlet  8  is formed in the right surface of the main body cabinet  1  at a position above the terminal port portion  7 . The air inlet  8  is constituted of multitudes of slit holes, and external air is drawn into the main body cabinet  1  through the air inlet  8 . 
         [0030]    A first air outlet  9  and a second air outlet  10  are formed in a left surface of the main body cabinet  1 . Each of the first and second air outlets  9 ,  10  is constituted of multitudes of slit holes, and air inside the main body cabinet  1  is discharged to the outside of the projector through the first and second air outlets  9 ,  10 . Further, a sound output port  11  is formed in a rear surface of the main body cabinet  1 . Sounds in accordance with images are outputted through the sound output port  11  at the time of image projection. 
         [0031]    Referring to  FIG. 2 , a fixed leg  12  is disposed in the middle of a front portion on a bottom surface of the main body cabinet  1 , and two adjustable legs  13  are disposed at a rear end thereof. By expanding or contracting the two adjustable legs  13  up and down, it is possible to adjust the inclination of the main body cabinet  1  in forward/rearward directions and leftward/rightward directions. Thus, it is possible to adjust the upward/downward position and the leftward/rightward inclination of an image projected on a screen. 
         [0032]    The projector of the embodiment may be installed in a suspended state from a ceiling with the main body cabinet  1  being upside down, other than an installation manner that the bottom surface of the main body cabinet  1  is placed on an installation plane such as a desk surface or a floor surface. Further, a front surface of the main body cabinet  1  is a flat surface without the terminal panel  240  and the air inlet  8 . Accordingly, it is possible to install the projector of the embodiment in such a manner that the front surface of the main body cabinet  1  is placed on an installation plane. In this case, an image is projected on the installation plane itself. 
         [0033]      FIG. 3  is a diagram showing an internal structure of the projector.  FIG. 3  is a perspective view showing a state that the upper cabinet  3  is detached, when viewed from a front side. To simplify the description, in  FIG. 3 , an imager unit  15  and a projection optical unit  17  are indicated by the dotted lines. Further, the position of the air inlet  8  is indicated by the one-dotted chain line. 
         [0034]    Referring to  FIG. 3 , a lamp unit  14 , and the imager unit  15  for modulating light from the lamp unit  14  to generate image light are disposed on a front portion of the lower cabinet  2 . 
         [0035]    The lamp unit  14  is constituted of a light source lamp, and a lamp holder for holding the light source lamp; and is configured so as to be detachably attached from above. A fan unit  16  is disposed behind the lamp unit  14 . The fan unit  16  supplies external air (cooling air) drawn through the air inlet  8  to the light source lamp to cool the light source lamp. The lamp holder is formed with an air duct for guiding the cooling air from the fan unit  16  to the light source lamp. 
         [0036]    The imager unit  15  includes a color wheel and a Digital Micromirror Device (DMD). The color wheel separates white light from the light source lamp into light of respective colors such as red, green, blue in a time-sharing manner. The DMD modulates the light of the respective colors emitted from the color wheel based on an image signal. 
         [0037]    The projection optical unit  17  is disposed at a rear position of the imager unit  15 . The projection optical unit  17  enlarges image light generated by the imager unit  15 , and projects the enlarged image light onto a projection plane such as a screen. 
         [0038]      FIG. 4  is a diagram schematically showing an arrangement of the projection optical unit  17 . In  FIG. 4 , the imager unit  15 , a control circuit unit  23 , and a noise filter unit  24  are schematically shown, in addition to the projection optical unit  17 . 
         [0039]    The projection optical unit  17  is constituted of a projection lens unit  101 , a reflection mirror  102 , and a housing  103  for housing the projection lens unit  101  and the reflection mirror  102 . The projection lens unit  101  has a plurality of lenses  101   a.  The reflection mirror  102  is a curved mirror or a free curved mirror. 
         [0040]    As shown in  FIG. 4 , image light emitted from the imager unit  15  is entered into the projection lens unit  101  at a position shifted from the optical axis L of the projection lens unit  101  in a direction toward the top surface of the main body cabinet  1 . The entered image light receives a lens function by the projection lens unit  101 , and is entered into the reflection mirror  102 . Thereafter, the projection angle of the image light is expanded by the reflection mirror  102 , and the image light is projected onto a projection plane (screen) via a light ray passage window  104 . 
         [0041]    As described above, image light is entered into the projection lens unit  101  at a position shifted from the optical axis L of the projection lens unit  101  in a direction toward the top surface of the main body cabinet  1 . In view of this, the reflection mirror  102  is disposed at a position shifted from the optical axis L of the projection lens unit  101  toward the bottom surface of the main body cabinet  1 . Here, the reflection mirror  102  has a reflection surface larger than the lens surface of each lens  101   a  constituting the projection lens unit  101 . Accordingly, the shift amount of the reflection mirror  102  with respect to the optical axis L of the projection lens unit  101  is relatively large. Consequently, there is defined a relatively large space G between a lower surface of the projection lens unit  101  and the bottom surface of the main body cabinet  1  (lower cabinet  2 ). The space G is defined from the position where the projection lens unit  101  is disposed to the position where the imager unit  15  is disposed. 
         [0042]    Referring back to  FIG. 3 , a power source unit  18  is disposed behind the fan unit  16 . The power source unit  18  is provided with a power source circuit to supply electric power to each electric component of the projector. A speaker  19  is disposed behind the power source unit  18 . Sounds outputted through the speaker  19  are released to the outside through the sound output port  11 . 
         [0043]    A DMD cooling fan  20  is disposed on the right of the imager  15 . The DMD cooling fan  20  supplies external air drawn through the air inlet  8  to the imager unit  15  so as to cool the DMD. 
         [0044]    A lamp exhaust fan  21  is disposed on the left of the lamp unit  14 . The lamp exhaust fan  21  draws the air that has cooled the light source lamp, and discharges the air to the outside through the first air outlet  9 . 
         [0045]    A power source exhaust fan  22  is disposed on the left of the power source unit  18 . The power source exhaust fan  22  draws warmed air inside of the power source unit  18 , and discharges the warmed air to the outside through the second air outlet  10 . By flowing the air from the inside of the power source unit  18  to the power source exhaust fan  22 , fresh external air is supplied into the power source unit  18  through the air inlet  8 . 
         [0046]    As shown in  FIG. 3  and  FIG. 4 , in the projector of the embodiment, the control circuit unit  23  and the noise filter unit  24  are disposed in the space G defined below the projection lens unit  101  and the imager unit  15 . 
         [0047]    The noise filter unit  24  is provided with a circuit board mounted with a noise filter and a fuse thereon, and supplies electric power inputted from a commercial AC power source to the power source unit  18  after noise removal. 
         [0048]      FIGS. 5A ,  5 B, and  6  are diagrams showing a configuration of the control circuit unit  23 .  FIG. 5A  is a perspective view of the control circuit unit  23  in which the main control board  210  and the extension interface board  220  are not yet built into the holder  250 .  FIG. 5B  is a perspective view of the control circuit unit  23  in which the main control board  210  and the extension interface board  220  are built into the holder  250 .  FIG. 6  is a plan view of the holder  250  as seen from underneath. 
         [0049]    Referring to  FIGS. 5A ,  5 B, and  6 , the control circuit unit  23  is formed by the main control board  210 , the extension interface board  220 , a fixing board  230 , a terminal panel  240 , and the holder  250 . 
         [0050]    The main control board  210  has a control circuit for controlling various drive parts such as a light source lamp, a DMD, and the like. In addition, the main control board  210  has at a right end thereof various terminals  211  and has at a center thereof a connector  212  for connection with a DMD wiring board  15   a.    
         [0051]    The main control board  210  has total six attachment holes  213  formed at four corners, between two front corners, and between two back corners. In addition, the main control board  210  has positioning holes  214  formed next to the attachment holes  213  at the three corners other than the left and back corners. In  FIG. 5A , the attachment holes  213  and the positioning holes  214  at the right and front corners are hidden by the terminal panel  240 . 
         [0052]    The extension interface board  220  has terminals  221  other than the terminals disposed on the main control board  210 . 
         [0053]    The fixing board  230  is made of a metallic material, and has the fixing portion  231  and the shielding portion  232  vertically integrated. The fixing portion  231  has one surface on which the interface board  220  and the main control board  210  are vertically aligned and fixed, and has the other surface on which the terminal panel  240  is fixed. The shielding portion  232  has a large number of openings  232   a  with metallic meshes (not shown). As shown in  FIG. 3 , when the control circuit unit  23  is attached to the main body cabinet  1 , the shielding portion  232  is disposed on an inner side of the air inlet  8 . External air taken in by the air inlet  8  flows into the main body cabinet  1  through the openings  232   a.  The shielding portion  232  blocks out electromagnetic waves that are about to leak outward from the air inlet  8 . 
         [0054]    The terminal panel  240  has openings shaped to be suitable for the terminals  211  and  221 . The terminals  211  and  221  are exposed from these openings. Although not shown, the fixing portion  231  of the fixing board  230  has also openings through which the terminals  211  and  221  pass. 
         [0055]    The holder  250  is made of a metallic material (for example, aluminum), and has an upper plate  251 , and a front plate  252  and a back plate  253  on front and back sides of the upper plate  251 , respectively. 
         [0056]    The upper plate  251  has an opening  254  through which the DMD wiring board  15   a  passes and an opening  255  for storing the bottom portion of the projection optical unit  17  at an incident end side. As shown in  FIG. 6 , the front plate  252  and the back plate  253  have six attachment pieces  256  corresponding to the six attachment holes  213  of the main control board  210 . The attachment pieces  256  have respective attachment holes  256   a.  In addition, the two attachment pieces  256  of the front plate  252  on the both sides and the attachment piece  256  of the back plate  253  at a right end have respective positioning projections  256   b  corresponding to the positioning holes  214  of the main control board  210 . 
         [0057]    Further, the front plate  252  and the back plate  253  have at left ends respective attachment pieces  257  for attaching the holder  250  to the main body cabinet  1 . These attachment pieces  257  have also attachment holes  257   a.    
         [0058]    As shown in  FIG. 5A , the main control board  210  and the extension interface board  220  are stored from underneath in a storage space surrounded by the upper plate  251 , the front plate  252 , and the back plate  253 . When stored in place within the storage space, the main control board  210  contacts the six attachment pieces  256  from underneath, and the three positioning holes  214  of the main control board  210  fit onto the corresponding positioning projections  256   b  of the attachment pieces  256 . Accordingly, the six attachment holes  213  of the main control board  210  are aligned with the corresponding attachment holes  256   a  of the attachment pieces  256 . Among the six attachment holes  213  of the main control board  210 , the two central attachment holes  213  and the corresponding attachment pieces  256  are fastened to each other by screws. Accordingly, as shown in  FIG. 5B , the main control board  210  and the extension interface board  220  are fixed to the holder  250 , whereby the control circuit unit  23  is completely assembled. At this point of time, the attachment holes  213  of the main control board  210  at the four corners and the corresponding attachment pieces  256  are not fastened to each other by screws. 
         [0059]    When the imager unit  15  (not shown in  FIG. 5B ) is attached to the top surface of the holder  250 , the DMD wiring board  15   a  connected to the DMD is inserted through the opening  254  into the storage space of the holder  250  as shown in  FIG. 5B . Then, a connector (not shown) formed on the DMD wiring board  15   a  is connected to the connector  212  on the main control board  210 . The DMD wiring board  15   a  has a signal line for the DMD through which drive signals from the DMD driver on the main control board  210  are transmitted to the DMD. 
         [0060]    In addition, the main control board  210  may discharge electromagnetic waves during operation, but the holder  250  made of a metallic material can block out such electromagnetic waves. 
         [0061]      FIG. 7  is a diagram showing a configuration of the optical unit U.  FIG. 8  is a diagram showing the main body cabinet  1  with the optical unit U not yet attached. 
         [0062]    As shown in  FIG. 7 , the lamp unit  14 , the imager unit  15 , the projection optical unit  17 , the fan unit  16 , and the DMD cooling fan  20  are fixed to the holder  250  of the control circuit unit  23 , by an appropriate fixing method such as screwing or the like. Accordingly, the control circuit unit  23 , the lamp unit  14 , the imager unit  15 , the projection optical unit  17 , the fan unit  16 , and the DMD cooling fan  20  are integrated into one optical unit U. 
         [0063]    As shown in  FIG. 8 , for fixation of the optical unit U, the lower cabinet  2  is provided with four attachment portions  25  corresponding to the four attachment pieces  256  of the holder  250  not yet screwed at incorporation of the main control board  210 , two attachment portions  26  corresponding to the two attachment pieces  257  at the left end of the holder  250 , and one attachment portion  27  corresponding to an attachment piece (not shown) provided on the housing  103  of the projection optical unit  17 . 
         [0064]    The optical unit U is fixed to the bottom surface of the lower cabinet  2  as shown in  FIG. 3 , the seven attachment pieces  256  and  257  by screws to the corresponding seven attachment portions  25 ,  26 , and  27  by fastening. As described above, the attachment holes  213  of the main control board  210  are aligned with the attachment holes  256   a  of the four attachment pieces  256 . Therefore, the main control board  210  is fastened together with the attachment pieces  256  to the attachment portions  25  by screws. Accordingly, the main control board  210  is firmly fixed by screws at the total six points to the holder  250 . 
         [0065]    If the main control board  210  is broken, the main control board  210  needs to be removed from the holder  250  for repair or replacement with a new main control board  210 . In this case, an engineer (service person) unscrews the seven screws fixing the optical unit U and removes the optical unit U from the main body cabinet  1 . After that, he/she unscrews the two screws to remove the main control board  210  from the holder  250 . 
         [0066]    Accordingly, this embodiment eliminates the need to follow a troublesome procedure: firstly removing the imager unit  15  and the projection optical unit  17  above the control circuit unit  23  from the main body cabinet  1 ; and then removing the control circuit unit  23  from the main body cabinet  1 . This facilitates replacement of the main control board  210 . 
         [0067]    As the foregoing, in this embodiment, when the reflection mirror  102  is disposed so as to be shifted from an optical axis of the projection lens unit  101 , a space G is produced under the projection lens unit  101  between the reflection mirror  102  and the main body cabinet  1 . The produced space G is used to dispose the main control board  210  and the extension interface board  220  in the space G. Disposing the boards in this manner makes the projector  1  less prone to be larger in dimension in the direction of projection. Accordingly, it is possible to make the outer shape of the projector  1  compact without deteriorating the projection capability of the projector  1 . 
         [0068]      FIG. 9  is a diagram showing one projection mode in this embodiment. In this embodiment, the main control board  210  and the extension interface board  220  are disposed in the space G as described above, which prevents a dimension D 1  of the main body cabinet  1  from becoming larger in the direction of projection. In this case, the direction of projection is the front-back direction shown in  FIG. 9 . 
         [0069]    In this embodiment, since it is possible to prevent the dimension D 1  from becoming larger as stated above, a shortest value of a throw distance (distance between the screen and the projection port  4  in the direction of projection) D 2  can be reduced. The throw distance D 2  becomes shortest when a front surface  c  of the main body cabinet  1  is pressed against a wall as shown in  FIG. 9 . 
         [0070]    In the projection mode of  FIG. 9 , it is possible to change a size of an image projected onto the screen with variations in the throw distance D 2  by moving the projector backward and forward. In this embodiment, since the shortest value of the throw distance D 2  can be reduced, a projected image can be made smaller in size, thereby providing a wider adjustment range of projected image size by moving the projector backward and forward. 
         [0071]    In this embodiment, since the main control board  210  and the extension interface board  220  are disposed in the space G, it is possible to prevent the main body cabinet  1  from becoming larger in height. Accordingly, the main body cabinet  1  does not block out projection light emitted from the projection port  4 . This allows the projector to be made compact without deteriorating the projection capability. 
         [0072]    In addition, in this embodiment, the main control board  210  and the extension interface board  220  are vertically aligned in the storage space of the holder  250 , that is, in the space G. Accordingly, the control circuit unit  23  can be smaller in dimension in the direction of projection, which makes it possible to further prevent that the dimension D 1  of the main body cabinet  1  becomes larger in the direction of projection. 
         [0073]    Further, in this embodiment, the terminal panel  240  is provided on the right surface of the main body cabinet  1  in a position corresponding to the space G in which the main control board  210  and the extension interface boad  220  are disposed. Accordingly, it is possible to form the air inlet  8  above the terminal panel  240 , that is, in a position corresponding to the imager unit  15  and the projection lens unit  101 , without interference by the terminal panel  240 . This allows the air inlet  8  to be made wider in area without interference by the terminal panel  240 . Therefore, it is possible to supply a large amount of intake air to the main body cabinet  1  and cool favorably heat-generating portions inside the main body cabinet  1 , such as the DMD of the imager unit  15 , and the like. 
         [0074]    Although an embodiment of the present invention is as described above, the present invention is not limited to this embodiment. In addition, the embodiment of the present invention can be appropriately modified in various manners within the scope of technical ideas shown in the claims. 
         [0075]    For example, in the foregoing embodiment, the DMD is used as an imager constituting the imager unit  15 . Alternatively, a liquid crystal panel may be used instead. 
         [0076]    In addition, in the foregoing embodiment, the lamp unit  14  having a light source lamp is used. Alternatively, any light source other than a lamp light source, for example, a laser light source or an LED light source may be used instead. 
         [0077]    Further, in the foregoing embodiment, the holder  250  holds the extension interface board  220  together with the main control board  210 . Alternatively, in addition to the extension interface board  220  or instead of the extension interface board  220 , the holder  250  may hold any other circuit board, for example, a communication circuit board, together with the main control board  210 . Such a communication circuit board has a communication circuit for performing communications between the projector and another device such as a personal computer or the like.

Technology Category: g