Abstract:
An image projecting apparatus including a base formed with a blowhole, a plurality of heat generating units disposed on a top portion of the base so as to communicate with the blowhole and generating heat when in operation, and a cooling fan disposed on a bottom of the base and cooling the plurality of heat generating units at the same time by blowing external air through the blowhole. Thus cooling down of heat generating units such as a lamp unit, a ballast unit, a colorwheel unit, etc., with a minimized number of fans is provided while reducing noise generated therefrom, and increasing cooling efficiency.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of Korean Patent Application No. 2004-33321, filed on May 12, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety and by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present general inventive concept relates to an image projecting apparatus, and more particularly, to an image projecting apparatus improving a cooling efficiency.  
         [0004]     2. Description of the Related Art  
         [0005]     Generally, an image projecting apparatus is an audio-visual apparatus used for a presentation or multimedia education, by projecting an image beam onto a screen connected to a computer, etc.  
         [0006]     The image projecting apparatus can be classified into an LCD (Liquid Crystal Display) type and a DLP (Digital Light Processing) type, etc., according to a display device displaying signal image information.  
         [0007]     A conventional image projecting apparatus comprises a plurality of heat generating units which necessarily generate heat in operation. Heat generated by the plurality of heat generating units is cooled compulsively using a separate cooling system.  
         [0008]     The image projecting apparatus has a limitation in cooling every heat generating unit using only one cooling fan due to the arrangement problem of these heat generating units. Accordingly, the image projecting apparatus supplies and distributes external air to each of these heat generating units, which need to be cooled by using a plurality of cooling fans or guide means, such as a duct, etc. The image projecting apparatus with the structure described above is disclosed in Korean Patent Application No. 2000-0050749 and Japanese Patent First Publication No. 2001-051349.  
         [0009]     However, in the case that these heat generating units are cooled by a plurality of cooling fans, noise due to cooling fans increases while cooling efficiency of the cooling system is decreased relatively.  
         [0010]     Further, when these heat generating units are cooled by the guide means, such as a duct, etc., a structure of the cooling system is relatively complicated and the volume of the image projecting apparatus is large. As a result, manufacturing costs increase due to these factors.  
       SUMMARY OF THE INVENTION  
       [0011]     Accordingly, it is an aspect of the present general inventive concept to provide an image projecting apparatus cooling down heat generating units such as a lamp unit, a ballast unit, a colorwheel unit, etc., with a minimized number of fans, thereby reducing noise generated therefrom.  
         [0012]     In addition, the present general inventive concept can directly cool a plurality of the heat generating units by using external air, thereby increasing cooling efficiency.  
         [0013]     Additional aspects and/or advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present general inventive concept.  
         [0014]     The foregoing and/or other aspects and advantages of the present general inventive concept are achieved by providing an image projecting apparatus comprising: a base formed with a blowhole; a plurality of heat generating units disposed on a top of the base so as to communicate with the blowhole, and generating heat in operation; and a cooling fan disposed on a bottom of the base, and cooling the plurality of heat generating units at the same time by blowing external air through the blowhole.  
         [0015]     According to an aspect of the present general inventive concept, the bottom of the plurality of heat generating units are opened so that external air blown up through the blowhole is introduced thereinto.  
         [0016]     According to an aspect of the present general inventive concept, the plurality of heat generating units comprises a lamp unit, a ballast unit and a colorwheel unit disposed adjacent to each other on the base.  
         [0017]     According to an aspect of the general inventive concept, the lamp unit comprises a lamp housing in which the external air blown from the cooling fan is introduced and which is in communication with the blowhole of the base; a lamp provided inside of the lamp housing; and an exhaust duct in communication with a top of the lamp housing.  
         [0018]     According to an aspect of the general inventive concept, the ballast unit comprises a ballast housing into which the external air blown from the cooling fan is introduced and which is in communication with the blowhole of the base, and has an exhaust part on a side thereof; and a ballast inside of the ballast housing.  
         [0019]     According to an aspect of the general inventive concept, the colorwheel unit comprises a colorwheel housing in communication with the blowhole of the base and in contact with the external air blown from the cooling fan; and a colorwheel inside of the colorwheel housing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     These and other aspects and advantages of the present general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompany drawings of which:  
         [0021]      FIG. 1  is a perspective view of an image projecting apparatus according to an embodiment of the present general inventive concept;  
         [0022]      FIG. 2  is a perspective view illustrating a configuration of a lamp unit of an image projecting apparatus, according to an embodiment of the present general inventive concept;  
         [0023]      FIG. 3  is a perspective view illustrating a configuration of a ballast unit of an image projecting apparatus, according to an embodiment of the present general inventive concept;  
         [0024]      FIG. 4  is a perspective view illustrating a configuration of a colorwheel unit of an image projecting apparatus, according to an embodiment of the present general inventive concept;  
         [0025]      FIG. 5  is a plan view illustrating a cooling structure of an image projecting apparatus, according to an embodiment of the present general inventive concept; and  
         [0026]      FIG. 6  is a bottom view illustrating a cooling structure of an image projecting apparatus, according to an embodiment of the present general inventive concept.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0027]     Reference will now be made in detail to the embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below so as to explain the present general inventive concept by referring to the figures.  
         [0028]     As shown in  FIGS. 1 through 4 , an image projecting apparatus according to an embodiment of the present general inventive concept may comprise a base  10 ; a plurality of heat generating units  20 ,  30  and  40  set on a top of the base  10  and generating heat in operation; a cooling fan  50  set on a bottom of the base  10  and cooling a plurality of heat generating units  20 ,  30  and  40  at the same time by blowing external air upward through the base  10 .  
         [0029]     The base  10  stably supports types of units including the plurality of heat generating units  20 ,  30  and  40  and has at a side thereof a blowhole  12  to blow the external air upward by the cooling fan  50 . The shape of the base  10  can be variously changeable according to the form and the arrangement of the image projecting apparatus. Also, the size of the blowhole  12  is as large as the size required to communicate with each of the heat generating units  20 ,  30  and  40 .  
         [0030]     The plurality of heat generating units  20 ,  30  and  40  can comprise a lamp unit  20 , a ballast unit  30  and a colorwheel unit  40 , which are disposed adjacent to each other on the top of the base  10 . It is an aspect of the present general inventive concept that the bottom of the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  are opened so that the external air blown upward through the blowhole  12  of the base  10  is introduced thereinto. However, closed bottoms of each of the heat generating units  20 ,  30 , and  40  can be provided as an alternative  
         [0031]     The plurality of heat generating units  20 ,  30  and  40  may comprise other kinds of units that necessarily need cooling while operating in the image projecting apparatus as well as the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40 .  
         [0032]     The lamp unit  20  projects white light of high brightness and can use an arc lamp, a laser, etc. The lamp unit provides a cut filter (not shown) and others, passing therethrough only visible rays and blocking off unnecessary light to display an image. The lamp unit  20  may comprise a lamp housing  22  in which the external air blown from the cooling fan  50  is introduced by being in communication with the blowhole  12  of the base  10 ; a lamp  24  provided inside of the lamp housing  22 ; and an exhaust duct  26  in communication with the top of the lamp housing  22 .  
         [0033]     The lamp housing  22  has a structure to easily and efficiently cool heat generated from the lamp  24 . According to the lamp housing structure, the external air blown upward is directly introduced into the lamp housing  22  since the bottom of the lamp housing  22  is opened to communicate with the blowhole  12  of the base  10 . The lamp housing  22  covers the lamp  24  and at the same time guides heat-exchanged external air that passes the lamp  24  and flows through the exhaust duct  26 .  
         [0034]     The exhaust duct  26  emits the external air introduced into the lamp housing  22  and passing the lamp  24 .  
         [0035]     The ballast unit  30  makes the operation of the lamp unit  20  stable and can stand up on the base  10  so as to improve cooling efficiency. The ballast unit  30  may comprise a ballast housing  32  in which the external air blown from the cooling fan  50  is introduced by being in communication with the blowhole  12  of the base  10 , and a ballast  34  inside of the ballast housing  32 .  
         [0036]     The ballast housing has a structure to efficiently cool heat generated from the ballast  34 . According to the structure, the external air blown upward by the cooling fan is directly introduced into the ballast housing  32  because the bottom of the lamp housing  22  is opened so as to communicate with the blowhole  12  of the base  10 .  
         [0037]     Moreover, the ballast housing  32  has an exhaust part  33   a  on a top of the ballast housing  32  to emit heat-exchanged external air through the ballast  34  and has a connecting part  33   b  on a side of the ballast housing  32  guiding the external air introduced into the ballast housing  32  to a guide duct  80 .  
         [0038]     The guide duct  80  is positioned to correspond to a heat sink  62  on a display device  60  to cool the display device  60  by using the external air introduced into the ballast housing  32 .  
         [0039]     The colorwheel unit  40  may comprise a colorwheel housing  42  in contact with the external air blown from the cooling fan  50  by being in communication with the blowhole  12  of the base  10 ; and a colorwheel  44  inside of the colorwheel housing  42  and dividing incident light to RGB beams.  
         [0040]     The colorwheel housing  42  is on a top portion of the blowhole  12  and is sealed up to prevent external materials from coming into contact with the colorwheel  44 . The colorwheel housing  42  is made of material that is able to cool heat generated from the colorwheel  44  by being in contact with the external air blown from the cooling fan  50 .  
         [0041]     The cooling fan  50  is on a bottom of the base  10 , and the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  are arranged on the flow-path of the external air blown upward by the cooling fan  50 . In other words, the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  all share the external air blown by the cooling fan  50  since the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  each communicate with the blowhole  12 .  
         [0042]     Accordingly, only one cooling fan  50  is required to cool the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  simultaneously, thereby improving cooling efficiency while reducing cost and noise.  
         [0043]     The cooling fan  50  can have a relatively high capacity to improve cooling efficiency, and can use a blower type fan that is superior in efficiency to a suction type fan, thereby reducing an operating voltage and a number of rotations. Alternative types of cooling units may be used which provide the intended purpose of the cooling fan  50  described above.  
         [0044]     The display device  60  modulates and reflects the RGB beams projected through the colorwheel unit  40  and usually uses a DMD panel. The DMD panel comprises a plurality of micromirrors, and the RGB beams are projected to the DMD panel and reflected at the micromirrors. The RGB beams reflected at the display device  60  are projected to a screen through the lens unit  70  to display a picture.  
         [0045]     A heat sink  62  is placed at the display device  60 , and a heat sink  62  is positioned to correspond to the guide duct  80 .  
         [0046]     The reference number  46  illustrates a cooling fin connected to the colorwheel  44 .  
         [0047]     The cooling system of the image projecting apparatus descrived above is operated as follows.  
         [0048]     At first, the external air blown by the cooling fan  50  is distributed and supplied respectively to the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  through the blowhole  12  of the base  10 .  
         [0049]     After the external air supplied to the lamp unit  20  performs a cooling operation, the external air is discharged through the exhaust duct  26 . Some of the external air introduced into the ballast unit  30  performs a cooling operation, and then is discharged through the exhaust part  33   a , and the rest of the external air cools the display device  60  by being guided to the guide duct  80  through the connecting part  33   b.    
         [0050]     The external air introduced into the colorwheel unit  40  performs a cooling operation by making contact therewith.  
         [0051]      FIG. 5  is a plan view illustrating a cooling structure of the image projecting apparatus and  FIG. 6  is a bottom view illustrating a cooling structure of the image projecting apparatus.  
         [0052]     As shown in  FIGS. 5 and 6 , the cooling fan  50  is on the bottom of the base  10 . The lamp unit  20 , the ballast unit  30  and the colorwheel unit  40 , as examples of heat generating units, are concentratively arranged on the top of the base  10  to correspond to the cooling fan  50 . Accordingly, the external air may be respectively introduced simultaneously to the lamp unit  20 , the ballast unit  30  and the colorwheel unit  40  by only one cooling fan  50 .  
         [0053]     Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.