Abstract:
An optical switch ( 1 ) having a sealing system connects to input fibers ( 42, 43 ) and output fibers ( 44, 45 ), and includes a switching device ( 5 ), a top housing ( 10 ), a bottom housing ( 30 ), a gasket ( 20 ) and four fiber clamps ( 40 ). The top and bottom housings each define a ringed channel ( 104, 304 ). The gasket is received in the ringed channels of the top and bottom housings. When screws combining the top and bottom housings together are tightened, the gasket deforms to fill the ringed channels, thereby forming a good seal between an inside and an outside of the housing.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an optical switch, and particularly to an optical switch having a sealing structure.  
           [0003]    2. Description of Related Art  
           [0004]    An optical switch is a passive optical component for switching optical signals between input fibers and output fibers, and is widely used in optical transmission systems and optical networks. To assure performance of the optical switch, the influence of the environment on the switch has to be reduced. Hence, a good sealing structure to protect the optical components in the switch is increasingly important.  
           [0005]    The sealing structure must provide for stability and isolation of the components, so must exclude dust and vapor from the optical switch housing. Present sealing systems mainly use epoxy resin to mount fibers in two housings, and bind housing halves together using screws. These systems provide low isolation, allowing vapor and dust to enter the housing, degrading optical efficiency of the optical components.  
           [0006]    For the above reasons, an improved sealing structure for optical switches is desired, which provides better stability and high isolation from the environment.  
         SUMMARY OF THE INVENTION  
         [0007]    An object of the present invention is to provide an optical switch having an improved sealing structure.  
           [0008]    Another object of the present invention is to provide a sealing structure for optical components which provides good stability and high isolation from the environment.  
           [0009]    An optical switch having an improved sealing structure connects with input fibers and output fibers and comprises a switching device, a top housing, a bottom housing ,an elastic gasket and a plurality of fiber clamps.  
           [0010]    The top and bottom housings are similar in shape, and together have the shape of a bottle. Each housing separately defines a channel for receiving the gasket. The gasket defines at least one annular opening for receiving a fiber clamp holding optical fibers. The gasket is received in the channels of the top and bottom housings. When screws are tightened in screw holes to combine the housing halves together, the pressure deforms the gasket so that the channels are filled by the gasket. Thus, good isolation is provided to an interior of the housing.  
           [0011]    A similar sealing system employing a top housing , a bottom housing, a gasket, and fiber clamps can be used to environmentally seal other optical components, such as optical couplers, optical connectors and optical attenuators.  
           [0012]    Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is an assembled view of an optical switch having a sealing structure according to the present invention;  
         [0014]    [0014]FIG. 2 is an exploded view of the optical switch of FIG. 1 with a top housing inverted for clarity; and  
         [0015]    [0015]FIG. 3 is a cross-sectional view taken along the line  3 - 3  in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]    As shown in FIGS. 1 and 2, an optical switch  1  for switching signals coming from input fibers  42 ,  43  between output fibers  44 ,  45  comprises a switching device  5 , a top housing  10 , a bottom housing  30 , four fiber clamps  40 , four collimators  41 , four boots  404 , and a gasket  20 .  
         [0017]    The top housing  10  and the bottom housing  30  are similar in shape, and together form roughly the shape of a bottle.  
         [0018]    The top housing  10  (shown upside-down in FIG. 2) comprises an inner wall  103  and an outer wall  102  with a plurality of screw holes  101  defined therein. A ringed channel  104  is defined between the inner wall  103  and the outer wall  102 . A pair of semi-annular openings  105  is defined in each of two lower sides and in each of two shoulders of the top housing  10 . Each pair of semi-annular openings  105  is respectively defined in the inner wall  103  and in the outer wall  102 , and a quadrate groove  106  is formed therebetween.  
         [0019]    The bottom housing  30  includes an inner wall  303 , an outer wall  302  and a plurality of screw holes  301 . A ringed channel  304  is formed between the inner wall  303  and the outer wall  302 . A pair of semi-annular openings  305  is defined in each of two lower sides and in each of two shoulders of the bottom housing  30 . Each pair of semi-annular openings  305  is respectively defined in the inner wall  303  and in the outer wall  302 , and a quadrate groove  306  is formed therebetween. The semi-annular openings  105  and the ringed channel  104  of the top housing  10  are similar to the semi-annular openings  305  and the ringed channel  304  of the bottom housing  30 . The bottom housing  30  further comprises a slot  308 , a mounting hole  309  and mounting walls  307 ,  310 ,  311 .  
         [0020]    The gasket  20  is substantially the same size and shape as the channels  104 ,  304  and is made of rubber or another elastic or ductile material. The gasket  20  comprises four quadrate flanges  206  for being received in the quadrate grooves  106 ,  306 . Each quadrate flange  206  defines an annular opening  208  for inserting a fiber clamp  40  therethrough. A plurality of through holes  201  is defined in the gasket  20 , placed to coincide with the screw holes  101 ,  301  of the top and bottom housings  10 ,  30 .  
         [0021]    The switching device  5  comprises a holding element  50 , a reflector  501 , a driving arm  60 , a two-surface mirror  601  and a driving means  70 . The holding element  50  holds the reflector  501  and is mounted in the slot  308  of the bottom housing  30 . The two-surface mirror  601  is held and driven to move up and down by the driving arm  60 . When the two-surface mirror  601  is displaced out of optical paths between the input fibers  42 , 43  and the output fibers  44 , 45 , the light signals from the input fibers  42 ,  43  are respectively transmitted directly to the output fibers  44  , 45 . However, when the two-surface mirror  601  is moved into the optical paths, one surface of the two-surface mirror faces the reflector  501  and the two-surface mirror  601  reflects the light signals from the input fiber  42  to the reflector  501 , and then the reflector  501  reflects the signals to the two-surface mirror  601 , thereafter the two-surface mirror  601  reflects the signals to the output fiber  45 ; the signals from the input fiber  43  are reflected to the output fiber  44  by the two-surface mirror  601 . The switching element  5  further comprises a stopper  80  received in the mounting hole  309  of the bottom housing  30 . The stopper  80  is used to limit downward travel of the two-surface mirror  601 . The driving means  70  drives the driving arm  60  to move the two-surface mirror  601  up and down.  
         [0022]    The optical switch  1  further comprises four fiber clamps  40 . Each fiber clamp  40  comprises a front flange  401 , an annular groove  402  and a rear flange  403 . Each fiber clamp  40  is inserted into a corresponding opening  208  of the gasket  20 , and the annular groove  402  engages with the annular opening  208 .  
         [0023]    In assembly, the switching device  5  is contained within an interior (not labeled) of the housing, formed by engagement of the top and bottom housings  10 ,  30  together. Four collimators  41  are separately mounted in the mounting walls  307 ,  310 ,  311  of the bottom housing  30  for collimating the signals. The input fibers  42 ,  43  and output fibers  44 ,  45  are each held in a corresponding fiber clamp  40  and boot  404 . The fiber clamps  40  are insert into the openings  208  of the gasket  20 . The annular groove  402  of each fiber clamp  40  engages with corresponding semi-annular openings  105 ,  305  in the top and bottom housings  10 ,  30  and with the opening  208  of the gasket  20 . Referring to FIG. 3, the gasket  20  is received in the ringed channels  104 ,  304  and quadrate grooves  106 ,  306  of the top and bottom housings  10 ,  30 . When screws (not shown) are threaded through the screw holes  101 ,  301  and through holes  201  and are tightened, the gasket  20  deforms under the pressure, filling the ringed channels  104 ,  304  and quadrate grooves  106 ,  306 . The interior (not labeled) of the housing is thereby well sealed and protected from contamination from outside the housing.  
         [0024]    The described sealing system, consisting of the top housing  10 , the bottom housing  30 , the gasket  20  and the fiber clamps  40  and boots  404 , can be used to seal other optical components, such as optical couplers, optical connectors and optical attenuators.  
         [0025]    It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.