Abstract:
A system and method of cooling a bulb of a type that requires cooling in one part, but not in others. A deflector assembly is coupled through a reflector, to the bulb, to cool only one part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present application claims benefit to U.S. Provisional application Ser. No. 60/179,981, filed Feb. 3, 2000. 
     
    
     
       BACKGROUND  
         [0002]    The present application relates for special techniques for cooling a special kind of bulb.  
           [0003]    Special metal halide bulbs have special cooling requirements. The bulbs, such as Philips metal halide projection lamps, often have a central portion which emits light, and two “pinch” portions around the central portion.  
           [0004]    A diagram of an exemplary one of these bulbs is shown in FIG. 1. The bulb has a central light emitting portion  100 , and the two surrounding “pinch” portions  102 ,  104 .  
           [0005]    In some bulbs, it is desirable to keep the pinch portions  102 ,  104  cooler than the center portion. This is easy to do in a laboratory condition, but more difficult to do in practice.  
         SUMMARY  
         [0006]    While it may be possible easy to cool only an edge and not the center in a laboratory, the inventor recognized that doing this in practicality can be more difficult. For example, in a laboratory, the bulbs are often cooled using pipes of air. Those pipes could get in the way of the light output from the bulb, and/or the bulb&#39;s reflector. Therefore, it has been difficult to cool these kinds of bulbs.  
           [0007]    The present application teaches a way of cooling a bulb of this type, by cooling only a pinch portion, and not the center portion. This is done by using a special combination of structure that cools at least one of the edges, but does not cool the center. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    These and other aspects will be described in detail with reference to the drawings in which:  
         [0009]    [0009]FIG. 1 shows a pinch-type bulb;  
         [0010]    [0010]FIG. 2 shows the bulb relative to a portion of the reflector;  
         [0011]    [0011]FIG. 3 shows the rear of the reflector and the fan assembly;  
         [0012]    [0012]FIG. 4 show the bulb/reflector from the bottom, showing the special interface piece;  
         [0013]    [0013]FIG. 5 shows air flow over the pinch, from the side;  
         [0014]    [0014]FIG. 6 shows air flow over the pinch from the orthogonal direction as FIG. 5;  
         [0015]    [0015]FIG. 7 shows the bulb with the reflector removed;  
         [0016]    [0016]FIG. 8 shows the air interface assembly. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    A bulb of the preferred type is shown in FIG. 1. This bulb has a central portion  100  which emits light, and edge portions  102 ,  104 , at least one of which need to be cooled. The central portion  100 , which emits the light, is preferably not cooled. The bulb used herein is called an MSR SA, or short arc discharge bulb. Other bulbs have similar cooling requirements.  
         [0018]    The edge portions  102 ,  104  should preferably be kept between  400  and 450° C. The bulb is mounted as shown in FIG. 2. When mounted in this way, the far edge portion  104  is often sufficiently cooled by ambient to be kept within the desired range. However, the near edge portion  102  gets very hot, due to the proximity to the ceramic base  110  and also because of its electrical connection. Also, as described above, cooling should not, or should only minimally, touch the center portion  100 .  
         [0019]    [0019]FIG. 2 shows the bulb  99  placed relative to a portion of the reflector  200 . The base portion  110  of the bulb is shown connected. The reflector  200  includes an outer edge  210  and an inner edge  220 . A metal air deflecting portion  230  fits within the inner edge  220 , and directs air from a fan to the close pinch portion  102  of the bulb which is close to the reflector.  
         [0020]    [0020]FIG. 3 shows the rear view of the system. An air chamber  300  is attached to a fan assembly shown generically as  310 . The fan assembly  310  forces into the air assembly  300 , and through the air coupling mechanisms  230 , to eventually end up at the bulb. Further detail is shown in the other Figures.  
         [0021]    [0021]FIG. 4 shows more detail of the shape of the air deflection assembly. FIG. 5 shows schematically how the air is coupled. The air couples through the assembly as  500 . It hits the far end wall  502  of the air coupling assembly  230 . This air is then deflected back towards the near pinch  102 , and travels thereover, cooling the near pinch  102  as it passes. The air is traveling away from the main portion of the bulb. In this system, the air preferably travels from the central portion towards the pinch.  
         [0022]    [0022]FIG. 6 shows a cross-section along the line  5 - 5  in FIG. 5. The air travels outwardly, as shown, and hence again travels away from the pinch portion.  
         [0023]    [0023]FIGS. 5 and 6 show the air chimney defined by the metal pieces  230 . These pieces are aligned relative to the bulb. The alignment is shown in more detail in FIG. 7 which shows the air producing assembly  230 , held in place relative to the bulb. The alignment can be via connection to the reflector in a way that holds the chimney relative to the desired cooled area of the bulb. It can be, alternatively, held by a clip that is placed around the bulb. The air producing assembly includes inner surfaces  232  which are adapted to press against the face  110 , to hold the air deflection assembly in place relative to the bulb or the bulb&#39;s expected position.  
         [0024]    [0024]FIG. 8 shows a diagram of only the air producing assembly and the attachment to the air chimney. The fan assembly  310  comprises two separate fans mounted one on top of the other as shown. Fans  312  and  314  produce air at the same rate as one fan would have produced but at a higher air pressure.  
         [0025]    Although only a few embodiments have been disclosed in detail, other embodiments are possible. All such modifications are intended to be encompassed within the following claims.