Abstract:
A light blocking apparatus is applied in an illuminating module of a projector. The light blocking apparatus includes a light shield and a support rod securing the light shield. The light shield is positioned in front of a bulb of the illuminating module. The support rod connects the light shield and another apparatus, such as a lamp reflector, so as to position the light shield in front of the bulb. The light shield is employed to block the light reflected from a UV-IR wheel and a color wheel so that the bulb won&#39;t be heated again.

Description:
RELATED APPLICATIONS  
       [0001]     The present application is based on, and claims priority from, Taiwan Application Serial Number 93130579, filed Oct. 8, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of Invention  
         [0003]     The invention relates to a cooling assistance apparatus and, in particular, to a light blocking apparatus.  
         [0004]     2. Related Art  
         [0005]     As shown in  FIG. 1 , the light source module of a conventional projector uses a light bulb  500 , whose light is collected by a reflective lampshade  700 , processed by a filter  400  and a color wheel  300 , and directed toward an optical engine. The conventional method of cooling a projector bulb  500  is to use a blower  800  to send cooling air toward the reflective lampshade  700 . When the cooling air passes by high-temperature points such as the lampwick  510 , the soldering point  520 , and the terminal  530 , it takes away the generated heat and sends the heat outside.  
         [0006]     Light collected by the reflective lampshade  700  goes through a filter  400 , filtering out the ultraviolet (UV) and infrared (IR) components, and produces red (R), green (G) and blue (B) light in consequence using a color wheel  300 . Therefore, part of the light is reflected by the filter  400  and the color wheel  300 . The UV, IR, and unpassed light is reflected back to the projector bulb  500 . As shown in  FIG. 1 , the reflected light is collected in the vicinity of the soldering point  520  and the terminal  520 . In addition to the heated generated by the soldering point  520  and the terminal  520  themselves, secondary heating is caused by the reflected light, resulting in inhomogeneous cooling of the projector bulb  500 .  
         [0007]     To solve this problem, the prior art usually increases the rotation speed of the blower or uses a larger blower  800 . However, using a larger blower will increase the volume of the blower and increasing the rotation speed of the blower may shorten the lifetime of the blower  800  and produce noises. Such methods may also result in over-cooling on the projector bulb  500  and other parts of the reflective lampshade  700 , affecting its performance and lifetime.  
       SUMMARY OF THE INVENTION  
       [0008]     Therefore, an objective of the invention is to provide a light blocking apparatus to block light reflected back to the projector bulb in front of the soldering point and the terminal, preventing them from being heated again and improving the cooling effect.  
         [0009]     Another objective of the invention is to provide a light blocking apparatus to improve the cooling effect while affecting the light source brightness as little as possible.  
         [0010]     A further objective of the invention is to provide a light blocking apparatus to improve the cooling effect without increasing its volume or the rotation speed of the blower.  
         [0011]     To achieve the above objective, the disclosed light blocking apparatus is used in the illuminating module of a projector, containing a light shield and a support rod. The light shield is disposed in front of the bulb of the illuminating module. The support rod connects the light shield and another apparatus, such as a lamp reflector, so as to position the light shield in front of the bulb. The light shield is employed to block the light reflected from a UV-IR wheel and a color wheel so that the bulb is heated again.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     These and other features, aspects and advantages of the invention will become apparent by reference to the following description and accompanying drawings which are given by way of illustration only, and thus are not limitative of the invention, and wherein:  
         [0013]      FIG. 1  is a schematic top view of the light propagation direction and cooling method in a conventional projector;  
         [0014]      FIG. 2A  is a schematic front view of the reflective lampshade of an illuminating module installed with the disclosed light blocking apparatus;  
         [0015]      FIG. 2B  is a schematic top view of the illuminating module in  FIG. 2A ;  
         [0016]      FIG. 3A  is a schematic side view of fixing the light blocking apparatus on the projector bulb;  
         [0017]      FIG. 3B  is a schematic side view of fixing the light blocking apparatus on the reflective lampshade; and  
         [0018]      FIG. 3C  is a schematic side view of fixing the light blocking apparatus on the fixed base. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]     The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.  
         [0020]     As shown in  FIGS. 2A and 2B , the disclosed light blocking apparatus  100  includes a light shield  110  and a support rod  120 . Viewing from the front of the reflective lampshade  700  as in  FIG. 2A , the light shield  110  is a circular shield. The central axis of the projector bulb  500  goes through the circular center of the circular shield. The support rod  120  is positioned at an edge of the light shield  110 , fixing it in front of the projector bulb  500 . As shown in  FIG. 2B , the projector bulb  500  is inside the reflective lampshade  700 . The axes of the reflective lampshade  700  and the projector bulb  500  coincide with each other, and the reflective lampshade  700  has an opening  710 . The center plumb line of the circular light shield  110  coincides with the axis of the projector bulb  500 , so that the plane of the light shield  110  is perpendicular to the axis of the projector bulb  500 . The rim of the light shield  110  is connected to the interface of an optical axis ineffective region  900 . When the light shield  110  falls within optical axis ineffective region  900 , the influence of the disclosed light blocking apparatus  100  on the light source brightness is reduced to the minimum, while there is the largest light blocking area in the optical axis ineffective region  900 .  
         [0021]     As shown in  FIG. 2B , light emitted by the lampwick  510  of the projector bulb  500  is reflected and collected by the reflective lampshade  700  to emit via the opening  710  of the reflective lampshade  700 . The filter  400  and the color wheel  300  remove some part of the light. The rest light goes through the filter  400  and the color wheel  300  toward an optical engine. When the light goes through the filter  400  and the color wheel  300 , some light is reflected by the filter  400  and the color wheel  300  back to the projector bulb  500 . However, the installation of the light shield  110  blocks the reflected light in front of the projector bulb  500 . The blocking can be achieved by absorbing or reflecting the light. Thus, the light does not continue its propagation to the terminal  530  and the soldering point  520 . The terminal  530  and the soldering point  520  are not heated again, rendering a better cooling effect.  
         [0022]     Various kinds of changes can be made within the spirit of the invention. For example, the materials of the light shield  110  and the supporting rod can be all kinds of high-temperature resistive substances. They can be made of the same material and formed together, same material and formed separately before connection, or different materials and formed separately before connection.  
         [0023]     The light shield  110  can be made of a material that absorbs light. Alternatively, a light reflecting coating or a light absorbing coating can be formed on the light shield  110 , on the surface that faces the filter  400  and the color wheel  300  but the projector bulb  500 . These methods can all block the light reflected from the filter  400  and the color wheel  400 , preventing it from going to the terminal  530  and the soldering point  520  in front of the projector bulb  500 .  
         [0024]     In the preferred embodiment shown in  FIGS. 2A and 2B , the light shield  110  is a circular light shield. In accord with the optical axis ineffective region of the projector bulb  500 , it is a circular cone with a circular cross section perpendicular to the axis. The rim of the light shield  110  is connected to the interface of the optical axis ineffective region  900 . This is to obtain the largest light blocking area with the least influence on the light source brightness. For the convenience of designs or to increase the light blocking area, the shape of the light shield  110  can be modified as long as the sacrificed light source brightness is taken into account. The light shield  110  can extend outside the optical axis ineffective region to increase the light blocking area. If the light shield  110  is made of a one-way transparent material, light can be emitted from inside the reflective lampshade  700  to outside the light shield. However, the reflected light cannot reach the projector bulb  500  because of the one-way transparent material. If the light blocking area goes beyond the optical axis ineffective region, the influence on the light source brightness can be further reduced.  
         [0025]     In the embodiment shown in  FIG. 2B , the plane of the light shield  110  is perpendicular to the central axis of the projector bulb  500 . However, the invention is not limited to such an example. As long as the above-mentioned light blocking function is achievable, the angle between the light shield  110  plane and the central axis of the projector bulb  500  can be any angle large than 0 degree and smaller than 180 degrees.  
         [0026]     The shape of the support rod  110  is not limited to those shown in  FIGS. 2A and 2B , either.  FIGS. 3A, 3B , and  3 C list all kinds of means to fix the light blocking apparatus  100 . As shown in the drawings, the disclosed light blocking apparatus  100  can be fixed onto the projector bulb or onto the reflective lampshade  700 . Moreover, the disclosed light blocking apparatus  100  can be installed on a fixed base  130  outside the projector bulb  500  and the reflective lampshade  700 .  
         [0027]     To minimize the influence of the disclosed light blocking apparatus  100  on the light source brightness, the support rod  120  preferably has a thin, long structure. However, it is not limited to such shapes.  FIGS. 3A, 3B , and  3 C show the disclosed light blocking apparatus from the side of the reflective lampshade. Although they all have two thin, long support rods  120  above and below the light shield  110  to fix the disclosed light blocking apparatus, the support rods  120  are not limited to such positions and their number is not limited to two. As long as the above-mentioned light blocking effect can be achieved, there can be any number of support rods in any shape and disposed at various positions. All such variations should be considered as part of the invention.  
         [0028]     One sees from the above preferred embodiment that the invention has the following advantages: 
        1. Light reflected from the projector bulb is blocked in front of the soldering point and the terminal, preventing them from being heated again and thus rendering a better cooling effect.     2. The light shield is disposed in the optical axis ineffective region. The cooling effect is improved with the least possible influence on the light source brightness.     3. It is not necessary to increase the volume or rotation speed of the blower to achieve the desired cooling effect.        
 
         [0032]     While the invention has been described by way of example and in terms of the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.