Abstract:
A light source unit including a mirror tunnel which has a prism-like shape and of which external sides are formed to taper and a light source made up of a light emitting device which is disposed on a side of the mirror tunnel. To provide a light source unit which is made small in size while enabling the installation therein of a larger number of light emitting devices such as LED&#39;s which constitute a light source than a conventional light source unit, as well as the expansion of a usable range of light radiated from the light emitting devices and a projector system utilizing the light source unit.

Description:
BACKGROUND OF THE INVETION  
       [0001]     1. Technical Field of the Invention  
         [0002]     The present invention relates to a light source unit and a projector system including the light source unit, and more particularly to a light source unit which enables the installation of a number of LED&#39;s therein as light sources and which is made small in size by increasing the utilization efficiency of light emitted from the LED&#39;s so installed and a projector system including the light source unit.  
         [0003]     2. Description of Related Art  
         [0004]     While many high pressure mercury lamps were used in light sources for projector systems, the high pressure mercury lamps had problems of large power consumption and short lives. Due to this, in recent years, light emitting diodes (LED&#39;s) have been in use instead due to small power consumption and long lives, as well as low heat generation, which less affects peripheral equipment.  
         [0005]      FIG. 7  is a schematic diagram which illustrates an example of a conventional projector system including a light source unit which uses LED&#39;s as light sources. A light source unit  31  provided in a projector system  30  is made up of a long transparent quadrangular prism-shaped mirror tunnel  32  and a light source  33  provided at one end of the mirror tunnel  32  which is made up of red, green and blue LED&#39;s. The LED&#39;s in the respective colors which make up the light source  33  are arranged in arrays.  
         [0006]     A lens  34  is provided on an optical axis K near the other end of the mirror tunnel  32  where the light source  33  is not provided.  
         [0007]     A reflector  35  is disposed on the optical axis K in a direction in which light emerging from the lens  34  travels in such a way that a surface of the reflector  35  which is to be illuminated by light so traveling is angled at a predetermined angle relative to the optical axis K.  
         [0008]     A micromirror device (a Digital Micromirror Device or DMD)  36  is disposed on the optical axis K in a direction in which light is reflected by the reflector  35 . A projection lens  37  is disposed on the optical axis K in a direction in which light is reflected by the micromirror device  36 . The projector system  30  is adapted to project an image by causing the respective red, green and blue LED&#39;s to emit light in the relevant colors in accordance with color indications by the micromirror element  36  for split indication of the respective colors.  
       SUMMARY OF THE INVENTION  
       [0009]     According to an aspect of the invention, there is provided a light source unit including a mirror tunnel which has a prism-like shape and of which external sides are formed to taper and a light source made up of a light emitting device which is disposed on a side of the mirror tunnel.  
         [0010]     In addition, according to another aspect of the invention, there is provided a light source unit including a mirror tunnel which is formed into a quadrangular pyramid shape and a light source made up of a light emitting device which is disposed on a side of the mirror tunnel.  
         [0011]     Additionally, a further aspect of the invention, there is provided a projector system including a light source unit which includes, in turn, a mirror tunnel which has a prism-like shape and of which external sides are formed to taper and a light source made up of a light emitting device which is disposed on a side of the mirror tunnel, a condenser which gathers light that emerges from the mirror tunnel, a reflector which reflects light that emerges from the condenser, a micromirror device which receives light reflected by the reflector so as to project an image, and a projection lens which enlarges the image projected from the mircromirror device.  
         [0012]     Furthermore, according to an aspect of the invention, there is provided a projector system including a light source unit which includes, in turn, a mirror tunnel which is formed into a quadrangular pyramid shape and a light source made up of a light emitting device which is disposed on a side of the mirror tunnel, a condenser which gathers light that emerges from the mirror tunnel, a reflector which reflects light that emerges from the condenser, a micromirror device which receives light reflected by the reflector so as to project an image, and a projection lens which enlarges the image projected from the mircromirror device.  
         [0013]     According to the invention, since the light emitting device is mounted on the side of the mirror tunnel, a required quantity of light can be secured without enlarging the mirror tunnel itself. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a top sectional view of a projector system according to a first embodiment of the invention.  
         [0015]      FIG. 2  is a schematic diagram which shows the configuration of the projector according to the first embodiment.  
         [0016]      FIG. 3  is an exemplary diagram which shows LED&#39;s making up a light source provided on a side of a mirror tunnel used in the first embodiment.  
         [0017]      FIG. 4  is a schematic sectional view of the mirror tunnel which shows optical paths of light within the mirror tunnel used in the first embodiment.  
         [0018]      FIG. 5  is a schematic diagram which shows the configuration of the projector according to a second embodiment.  
         [0019]      FIG. 6  is a schematic sectional view of the mirror tunnel which shows optical paths of light within the mirror tunnel used in the second embodiment.  
         [0020]      FIG. 7  is a schematic sectional view of a conventional projector.  
         [0021]      FIG. 8  is a schematic sectional view of a conventional mirror tunnel which shows optical paths of light within the mirror tunnel. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENTS  
     First Embodiment  
       [0022]     Next, a first embodiment of the invention will be described by reference to the drawings. Claims are, however, not limited by an illustrated example.  
         [0023]      FIG. 1  is a top sectional view of a projector system  1 . A case  2  is provided on the projector system  1 , and a power supply circuit board  3  having a power supply mounted thereon is provided in the interior of the projector system  1  for controlling the whole of the projector system  1 . In addition, a mirror tunnel  5 , on which LED&#39;s functioning as a light source are mounted, is disposed near a central portion of the projector system, and a reflector  6  is mounted on the mirror tunnel  5 . A lens  7  is disposed in a direction in which light emerging from the mirror tunnel  5  travels. A projection unit  9 , which will be described later on, is disposed in a direction in which light emerging from the lens  7  travels, and a reflector  13 , a micromirror device  14  and a projection lens  15  are accommodated in the projection unit  9 .  
         [0024]     In addition, a multiblade fan  10  is disposed in the projector system  1  which is a cooling fan for blowing cooling air against the LED&#39;s mounted on the mirror tunnel  5  so as to cool them. An axial fan  11  is provided in a backward direction of the reflector  6  mounted on the mirror tunnel  5  for producing an air flow on the periphery of the mirror tunnel  5 .  
         [0025]      FIG. 2  is a schematic diagram which shows a configuration inside the projector system  1 . A light source unit  4  is provided in the projector system  1 . The light source unit  4  is made up of the mirror tunnel  5 , the reflector  6  that is provided on an end face of the mirror tunnel  5  and the light source  12  that are mounted on the mirror tunnel  5 .  
         [0026]     The mirror tunnel  5  is such as to be designed to guide light emitted from the light source  12  and is made of a transparent material. The mirror tunnel  5  has a prism-like shape and external sides thereof are formed to taper, and the reflector  6  is provided on an end face of the mirror tunnel  5  of which the area is smaller in such a manner that a reflecting surface of the reflector  6  is brought into contact with the end face of the mirror tunnel  5 .  
         [0027]     The lens  7  is provided on an optical axis K near the other end of the mirror tunnel  5  where the reflector  6  is not provided so as to enlarge a bundle of rays that emerges from the mirror tunnel  5 .  
         [0028]     The projection unit  9  is disposed in a direction in which light emerges from the lens  7  to travel further, and the reflector  13 , which makes up the projection unit  9 , is disposed on the optical axis K of light that has emerged from the lens  7  in such a manner that a surface thereof which is illuminated by the light that has emerged from the lens  7  has a predetermined angle relative to the optical axis K.  
         [0029]     The micromirror device  14  is disposed on the optical axis K in a direction in which light is reflected by the reflector  13 . The projection lens  15  is disposed on the optical axis K of light that is reflected by the micromirror device  14 .  
         [0030]     The light source  12  is made up of a light emitting device, and there is no limitation on the type of the light emitting device, provided that the light emitting device is such as to provide a quantity of light that is required at the light source unit and the projector system. As the light emitting device, for example, an LED is raised. In the following description, a case will be described in which LED&#39;s are used as light sources.  
         [0031]     As shown in  FIG. 3 , the light source  12  is disposed on a side of the mirror tunnel  5 , and in the light source  12 , red LED&#39;s  16 , green LED&#39;s  17  and blue LED&#39;s  18  are disposed along a longitudinal axis L or a longitudinal direction L and a direction which intersects with the longitudinal axis L at right angles in such a manner that the LED&#39;s in the same color are not adjacent to each other in both the directions. The respective LED&#39;s are disposed in such a manner as to be spaced apart from each other at such a distance that no adverse effect is imparted to the adjacent LED&#39;s by heat generated when the LED&#39;s are caused to emit light.  
         [0032]     The LED&#39;s are designed to be provided on a side of the mirror tunnel  5 , and the LED&#39;s are preferably disposed over an area of not less than a quarter or one-half the total area of the side at predetermined intervals and are most preferably disposed over the whole area of the side at the predetermined intervals.  
         [0033]     Note that while the light source  12  is mounted on only the one side of the mirror tunnel in  FIG. 2 , the mounting of the light source  12  on the mirror tunnel  5  is not limited to one side of the mirror tunnel  5  but the light source  12  may be provided on a plurality of sides of the mirror tunnel  5 .  
         [0034]     The respective LED&#39;s, which make up the light source  12 , are made to synchronize with an image display timing of the micromirror device  14 . The micromirror device  14  is designed to display a red image when the red LED&#39;s are lighted and when the green LED&#39;s and blue LED&#39;s are lighted, the mircromirror device  14  displays images corresponding to the respective colors.  
         [0035]     In addition to the individual lighting of the red LED&#39;s, the green LED&#39;s and the blue LED&#39;s, the respective LED&#39;s, which make up the light source  12 , are also designed to be lighted altogether at the same time to produce white light when brightness is necessary for an image to be displayed, and the micromirror device  14  is also designed to operate to display an image which corresponds thereto.  
         [0036]     The lens  7  is such as to guide light emerging from the mirror tunnel  5  to the reflector  13 . While the lens  7  is illustrated as a single lens element in  FIGS. 1 and 2 , the lens  7  may be made up of a plurality of lens elements.  
         [0037]     The reflector  13  is such as to reflect light that is guided to be incident thereon by the lens  7  and guide light so reflected towards the direction of the mircromirror device  14 .  
         [0038]     The micromirror device  14  is such as to project an image by forming individual pixels for an image to be displayed by a plurality of micromirrors and changing over light and shade of the pixels by changing over the inclination of the micromirrors.  
         [0039]     The micromirrors are formed of extremely thin metallic pieces such as aluminum pieces and have vertical and horizontal widths which range from 10 μm to 20 μm. These micromirrors are provided, respectively, on a plurality of mirror drive devices (not shown) such as CMOS which are formed into a matrix-like arrangement in row and column directions.  
         [0040]     The projection lens  15  is such as to enlarge and project reflected light from the micromirror device  14  on to a screen (not shown). Note that the projection lens  15  is illustrated as a single lens element in  FIG. 2 , the projection lens  15  may be made up of a plurality of lens elements.  
         [0041]     Next, the function of the first embodiment will be described.  
         [0042]     When the projector system  1  is activated, light is emitted from the light source  12  provided on the side of the mirror tunnel  5 .  FIG. 4  is a schematic diagram which shows optical paths of light emitted from one of the LED&#39;s which make up the light source  12  with a view to clarifying optical paths of light emitted from the light source  12 . As shown in  FIG. 4 , part E of light emitted from the LED making up the light source  12  is emitted towards the direction of the reflector  6 , then impinges on side walls of the mirror tunnel  5  and is thereafter reflected towards the direction of the side where the light source  12  is provided. Thus, the part E of light repeats these reflections and is eventually guided towards the direction of the lens  7 . In addition, the other part F of the light emitted from the LED making up the light source  12  impinges on a side of the mirror tunnel  5  which oppositely faces the side where the light source  12  is disposed to thereby be reflected thereon and is thereafter guided towards the direction of the lens  7 .  
         [0043]     Thus, the parts E and F, which constitute part of the light emitted from the light source  12 , are to be caused to emerge from the mirror tunnel  5  at a smaller angle relative to an interface between the sides of the mirror tunnel  5  and layers of outside air compared with a case where light is caused to emerge from a quadrangular prism-shaped mirror tunnel having a square cross section.  
         [0044]     Light emerging from the mirror tunnel  5  is gathered by the lens  7  and is then caused to be incident on the reflector  13 . Light so incident on the reflector  13  is reflected so as to be guided towards the micromirror device  14 . Light that is caused to be incident on the micromirror device  14  is enlarged by the projection lens  15  and is then projected on to the screen, not shown.  
         [0045]     Thus, as has been described heretofore, according to the projector system of the first embodiment of the invention, a required quantity of light can be secured without enlarging the mirror tunnel itself.  
         [0046]     In addition, since by forming the shape of the mirror tunnel  5  into a taper shape so that the cross sectional area of the mirror tunnel  5  is expanded from the one end face to the other thereof, a ratio of quantity of usable light of light that emerges from a light emerging surface of the mirror tunnel  5  can be increased, it is possible to provide a light source unit which can obtain a more sufficient quantity of light.  
         [0047]     In addition, since irregularities in color of light projected by the micromirror device which are generated when white light is emitted can be reduced even when white light is emitted by the LED&#39;s, it is possible to obtain a clear image.  
         [0048]     Additionally, since the mirror tunnel  5  is formed to taper in such a manner that the cross sectional area thereof expands from the one end face to the other thereof, the area of the light emerging surface of the mirror tunnel  5  becomes wide, whereby a usable range of light emitted from the LED&#39;s can be expanded.  
       Second Embodiment  
       [0049]     Next, a second embodiment of the invention will be described. However, in the description of the second embodiment, only those which differ from the first embodiment will be described, and the description of the same configurations as those of the first embodiment will be omitted here.  
         [0050]      FIG. 5  is a schematic diagram which shows the configuration within a projector system  20 . A light source unit  21  is provided in the projector system  20 , and the light source unit  21  is made up of a mirror tunnel  22  and a light source  12  mounted on the mirror tunnel  22 .  
         [0051]     The mirror tunnel  22  is such as to guide light emitted from the light source  12  to a lens  7  and is made of a transparent material. The mirror tunnel  22  is formed into a quadrangular pyramid shape.  
         [0052]     The light source  12  made up of LED&#39;s is disposed on a side of the mirror tunnel  22 , and in the light source  12 , red LED&#39;s  16 , green LED&#39;s  17  and blue LED&#39;s  18  are disposed along a longitudinal axis L and in a direction which intersects with the longitudinal axis L at right angles in such a manner that the LED&#39;s in the same color are not adjacent to each other in both the directions. The respective LED&#39;s are disposed in such a manner as to be spaced apart from each other at such a distance that no adverse effect is imparted to the adjacent LED&#39;s by heat generated when the LED&#39;s are caused to emit light.  
         [0053]     The LED&#39;s are designed to be provided on a side of the mirror tunnel  22 , and the LED&#39;s are preferably disposed over an area of not less than a quarter or one-half the total area of the side at predetermined intervals and are most preferably disposed over the whole area of the side at the predetermined intervals.  
         [0054]     The respective LED&#39;s, which make up the light source  12 , are made to synchronize with an image display timing of a micromirror device  14 . The micromirror device  14  is designed to display a red image when the red LED&#39;s are lighted and when the green LED&#39;s and blue LED&#39;s are lighted, the mircromirror device  14  displays images corresponding to the respective colors.  
         [0055]     In addition to the individual lighting of the red LED&#39;s, the green LED&#39;s and the blue LED&#39;s, the respective LED&#39;s, which make up the light source  12 , are also designed to be lighted altogether at the same time to produce white light when brightness is necessary for an image to be displayed, and the micromirror device  14  is also designed to operate to display an image which corresponds thereto.  
         [0056]     Next, the function of the second embodiment will be described.  
         [0057]     When the projector system  20  is activated, light is emitted from the light source  12  provided on the side of the mirror tunnel  22 .  FIG. 6  is a schematic diagram which shows optical paths of light emitted from one of the LED&#39;s which make up the light source  12  with a view to clarifying optical paths of light emitted from the light source  12 .  
         [0058]     As shown in  FIG. 6 , part H of light emitted from the LED making up the light source  12  is emitted towards an opposite direction to the lens  7 , then impinges on side walls of the mirror tunnel  22  and is thereafter reflected towards the direction of the side where the light source  12  is provided. Thus, the part H of light repeats these reflections and is eventually guided towards the direction of the lens  7 . In addition, a part I which is the other part of the light emitted from the LED making up the light source  12  impinges on a side of the mirror tunnel  22  which oppositely faces the side where the light source  12  is disposed to thereby be reflected thereon and is thereafter guided towards the direction of the lens  7 .  
         [0059]     Thus, as in the case with the mirror tunnel  5  used in the first embodiment, the parts H and I, which constitute part of the light emitted from the light source  12 , are to be caused to emerge from the mirror tunnel  22  at a smaller angle relative to an interface between the sides of the mirror tunnel  22  and layers of outside air compared with a case where light is caused to emerge from a quadrangular prism-shaped mirror tunnel having a square cross section.  
         [0060]     Light emerging from the mirror tunnel  22  is gathered by the lens  7  and is then caused to be incident on the reflector  13 . Light so incident on the reflector  13  is reflected so as to be guided towards the micromirror device  14 . Light that is caused to be incident on the micromirror device  14  is enlarged by a projection lens  15  and is then projected on to the screen, not shown.  
         [0061]     Thus, as has been described heretofore, according to the projector system of the second embodiment of the invention, the same advantage as that of the first embodiment can be obtained.