Abstract:
An optical switch ( 10 ) includes a housing ( 3 ), an input port ( 4 ), an output port ( 5 ), a switching element ( 6 ), a holder ( 7 ), and a driver ( 63 ). The holder holds the input and output ports in alignment with one another and is assembled with the switching element. The switching element includes an optical component assembly ( 61 ) and a rotating mechanism ( 60 ). The optical component assembly is fixed on the rotating mechanism and is brought to move between a top stopper ( 85 ) (an upward position), wherein the optical component assembly is out of optical paths running between the input port and the output port, and a bottom stopper ( 86 ) (a downward position), wherein the optical component assembly is in the optical paths. The optical component assembly includes a prism ( 612 ), which redirects optical paths passing through it, thereby effecting switching between the input and output ports.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical switch for use in optical fiber communication and optical network technology, and particularly to an optical switch that can precisely locate a movable optical component to preselected positions for realizing optical paths switching. 
   2. Description of Related Art 
   Optical signals are commonly transmitted in optical fibers, which provide efficient light channels through which optical signals can pass. Recently, optical fibers have been used in various fields, including telecommunications, where light passing through an optical fiber is used to convey either digital or analog information. Efficient switching of optical signals between individual fibers is necessary in most optical processing systems or networks to achieve the desired routing of the signals. 
   In optical fiber systems, various mechanisms have been previously developed for switching optical signals between fiber cables. Among these previously developed mechanisms, one important category is mechanical optical switches. 
   Mechanically operated optical switches come in two different designs: in one design, the optical components move, and in the other design, the fibers move. Factors for assessing the capability of an optical switch include low insertion loss (&lt;1 dB), good isolation performance (&gt;50 dB) and bandwidth capacity compatible with the fiber network the switch is supporting. 
   In moving optical component switches, a driving mechanism drives one or more optical components to move between different positions to effect the switching operation. The driving mechanism may be a motor or a solenoid with no self-latching mechanism, which needs an attached latching mechanism to locate the optical component in the different positions. In general, the attached mechanism is large in size. As shown in  FIG. 10 , U.S. Pat. No. 5,742,712 describes a mechanical optical switch  910  having a relay  912 . The relay  912  includes an arm  940 , which supports a mirror  920 . In response to electrical signals supplied to the relay  912 , the arm  940  of the relay  912  moves the mirror  920  between a first position  944  and a second position  946 . The travel of the arm  940  is limited by stops  948 , which determine the first and second positions of the mirror  920 . 
   In this mechanical optical switch  910 , the stops  948  are opposite a middle part of the arm  940 . The weight of the mirror  920  bends the arm  940  over time, which results in misalignment of the mirror  920  and connected fibers  990 . 
   For the above reasons, an improved optical switch is desired. In particular, an optical switch is desired which has high optical efficiency and which can precisely position the switching element in the different switching states. 
   BRIEF SUMMARY OF THE INVENTION 
   An object of the invention is to provide an optical switch which includes a rotating mechanism to effect switching states. 
   Another object of the invention is to provide an optical switch which provides precise positioning of associated switching elements in the different switching states and which has a low insertion loss. 
   Yet another object of the present invention is to provide an optical switch which is small in size. 
   An optical switch in accordance with one embodiment of the present invention comprises a housing, a switching element, a driver, a holder, an input port and an output port. The switching element, the driver and the holder are accommodated in a chamber formed in the housing. The holder holds the input and output ports in alignment with one another and is assembled with the switching element, which comprises an optical component assembly and a rotating mechanism. The optical component assembly is soldered to the rotating mechanism and can be moved between a bottom stopper (a downward position), where a prism of the optical component assembly is in the optical paths between the input port and the output port, and a top stopper an upward position), where the prism of the optical component assembly is out of the optical paths. 
   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 
       FIG. 1  is an exploded view of an optical switch of the present invention; 
       FIG. 2  is a perspective view of a holder and aligned collimators of the optical switch in  FIG. 1 ; 
       FIG. 3  is a partially exploded view of a holder, aligned collimators, and a switching element of the optical switch in  FIG. 1 ; 
       FIG. 4  is an assembled view of  FIG. 3 , without an optical component assembly; 
       FIG. 5  is an assembled view of  FIG. 3 , from a reverse aspect, additionally having a driver shaft and showing the optical component assembly in a downward position; 
       FIG. 6  is an essential optical paths diagram of the optical switch of  FIG. 1 , when the optical component assembly is in the downward position; 
       FIG. 7  is the same as  FIG. 5 , but with the optical component assembly in an upward position; 
       FIG. 8  is a cross-sectional view taken along the line  8 — 8  in  FIG. 7 ; 
       FIG. 9  is an essential optical paths diagram of the optical switch in  FIG. 1 , when the optical component assembly is in the upward position; 
       FIG. 10  is a partially cross-sectional view of a prior art optical switch. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , an optical switch  10  according to the present invention switches signals coming from a first and second input fibers  41 ,  42  between first and second output fibers  51 ,  52 . The optical switch  10  comprises a housing  3 , a switching element  6 , a driver  63 , a holder  7 , an input port  4 , an output port  5 , a top stopper  85  and a bottom stopper  86 . The housing  3  comprises an elongate, box-shaped base  31  defining two opposite side holes  311 ,  312  having interior threads therein, and a top cover  2  defining a slot  21 . The housing  3  accommodates the switching element  6 , the driver  63 , the holder  7 , the top stopper  85 , the bottom stopper  86 , and parts of the input and output ports  4 ,  5 , as described below, therewithin. 
   As shown in  FIGS. 2 and 3 , the holder  7  has a horizontal base plate  741  with an elongate mounting pedestal  74  extending upwardly from a central portion (not labeled) of the base plate  741 . A first and second collimator holders  731 ,  732  protrude upwardly at a forward side of the base plate  741 , each defining two collimator notches (not labeled) therein. A pair of shaft supporters  743 ,  744  protrudes upwardly from a rear side of the base plate  741 , each defining a V-angled slot  746 ,  747  therein for accepting two ends of an axle shaft  65 . A pair of anchor holes  71 ,  72  is defined in a top of the mounting pedestal  74 . Two spring mounting holes  742  are defined in a rear side of the mounting pedestal  74  and a guiding hole  733  is defined in the forward side of the base plate  741  between the two collimator holders  731 ,  732 . A chamber  73  is formed between the base plate  741 , the two collimator holders  731 ,  732 , and the mounting pedestal  74 . A bracket mounting notch  745  is formed between the base plate  741 , the two shaft supporters  743 ,  744 , and the mounting pedestal  74 . 
   Also referring to  FIGS. 2–4 , the switching element  6  comprises an optical component assembly  61  and a rotating mechanism  60 . The optical component assembly  61  includes an optical component  612  and an optical component holder  611  engaged with the optical component  612 . In this embodiment, the optical component  612  is a diamond-shaped prism  612 . 
   The rotating mechanism  60  comprises a bracket  62 , a cantilevered spring  64 , and the axle shaft  65 . The bracket  62  is formed from one bent piece of sheet metal, and comprises a frame  622  and a lifting arm  621 . The frame  622  is roughly in the shape of an elongate rectangular box, with the lifting arm  621  bending upwardly and outwardly from a side (not labeled) of the frame  622 . A pair of drive bearings  625  protrudes upwardly from a top side (not labeled) of the frame  622 , each drive bearing  625  defining one of a pair of aligned drive holes  624  therethrough. Each of a pair of frame end walls (not labeled) defines a shaft hole  623  therethrough. 
   The cantilevered spring  64  is made of a resilient material, and has a fixing arm  642  on one end and a spring arm  641  on an opposite end. The fixing arm  642  defines two arm holes (not labeled). The spring arm  641  is bent in a sinuous shape to provide a spring force against the axle shaft  65 . The axle shaft  65  is long and cylindrical in shape, and is beveled on one end to aid in inserting the axle shaft  65  through the shaft holes  623 . 
   The driver  63  (see  FIG. 1 ) is a relay having a self-latching function, and drives the bracket  62  to rotate. The driver  63  has a driver arm  632  extending outwardly therefrom, and an L-shaped driver shaft  631  soldered on the driver arm  632 . The driver arm  632  moves in a forward and rearward direction. 
   Referring to  FIGS. 1–2 , the input port  4  comprises a first and a second input collimators  81 ,  82 , a coupler  44 , and a boot  43 . The output port  5  comprises a first and a second output collimators  91 ,  92 , a coupler  54 , and a boot  53 . The first input collimator  81  has a ferrule  801  and a lens  802 , which are held in fixed relation to one another using epoxy or solder between angled front and back surfaces  803 ,  804  of the ferrule  801  and the lens  802 , respectively. The lens  802  may be a GRIN (Graded Index) lens. The ferrule  801  is an elongate tube having a hollowed out interior aperture (not labeled) extending longitudinally therethrough, wherein the first input fiber  41  can be inserted. The second input collimator  82  and the first and second output collimators  91 ,  92  are identical in structure with the first input collimator  81 , but respectively receive the second input fiber  42 , the first output fiber  51 , and the second output fiber  52 . Each coupler  44 ,  54  has a tubular construction with a threaded outer surface (not labeled) on one end. 
   In assembly, the optical component assembly  61  is connected to the bracket  62  by soldering the optical component holder  611  to the lifting arm  621 . The axle shaft  65  is inserted through the shaft holes  623  in each frame end wall (not labeled), and ends (not labeled) of the axle shaft  65  are engaged in corresponding V-angled slots  746 ,  747 , while the frame  622  of the bracket  62  fits into the bracket mounting notch  745 . The fixing arm  642  of the cantilevered spring  64  fits against the mounting pedestal  74 , with the two arm holes (not labeled) aligned with the spring mounting holes  742 , and with the spring arm  641  pressing against the axle shaft  65 . Two arm screws  89  are inserted through the arm holes of the fixing arm  642  and are engaged in the spring mounting holes  742 . The first and second input collimators  81 ,  82  are fixed in the collimator notches (not labeled) of the input collimator holder  731 , and the first and second output collimators  91 ,  92  are fixed in the collimator notches (not labeled) of the second collimator holder  732 . The first input collimator  81  is aligned with the first output collimator  91 , and the second input collimator  82  is aligned with the second output collimator  92 . The bottom stopper  86  is engaged with the guiding hole  733  in the holder  7 . The driver shaft  631  of the driver  63  is inserted through the drive holes  624  in the bracket  62 , and the holder  7  and driver  63  are inserted into the base  31 . A pair of anchor screws  88  is inserted through the anchor holes  71 ,  72  and engaged with the base  31 , thereby fixing the holder  7  securely in the base  31 . The couplers  44 ,  54  are threadedly engaged in the respective side holes  311 ,  312 . The first and second input fibers  41 ,  42  are threaded through the boot  43  and the coupler  44  and are fixed in the ferrules of, respectively, the first and second input collimators  81 ,  82 . The first and second output fibers  51 ,  52  are threaded through the boot  53  and the coupler  54  and are fixed in the ferrules of, respectively, the first and second output collimators  91 ,  92 . The boots  43 ,  53  are moved to cover rearward ends of the respective couplers  44 ,  54 . The top stopper  85  is fixed in the slot  21  of the top cover  2 , which is fixed to the base  31 . 
   In use, the optical component assembly  61  is moved between a lowered position and a raised position. When the driver arm  632  of the driver  63  is in a forward position, the prism  612  is in the lowered position, as shown in  FIG. 5 . When the driver  63  receives a signal to move to a rearward position, the driver arm  632  with the attached driver shaft  631  moves rearward. Since the driver shaft  631  is engaged with the drive bearing  625  on the bracket  62  via the drive holes  624 , the drive bearing  625  is also driven rearward with the driver shaft  631 . This rearward movement of the drive bearing  625  rotates the bracket  62  around the axle shaft  65 , which raises the lifting arm  621  and the prism  612 , as shown in  FIGS. 7–8 , until the lifting arm  621  abuts the top stopper  85 . When the driver  63  receives a signal to move to the forward position, the process is reversed and the prism  612  is lowered until the optical component assembly  61  abuts against the bottom stopper  86 . 
     FIGS. 5–9  illustrate the operation of the optical switch  10 . In the downward position ( FIGS. 5 and 6 ), the optical component assembly  61  is stopped against the bottom stopper  86 , and the prism  612  aligns with the input and output collimators  81 ,  82 ,  91 ,  92 . Light beams from the first and second input fibers  41 ,  42  transmit through the first and second input collimators  81 ,  82 , respectively. Each light beam is transmitted through the prism  612 , and is bent along symmetrically opposite paths by the prism, to pass through the second and first output collimators  92 ,  91  and into the second and first output fibers  52 ,  51 , respectively. 
   In the upward position ( FIGS. 7–9 ) of the optical component assembly  61 , the lifting arm  621  abuts against the top stopper  85 , with the prism  612  being out of the optical paths between the input and output ports  4 ,  5 . In this position, light beams from the first and second input fibers  41 ,  42  are transmitted through the first and second input collimators  81 ,  82 , and transmit through the first and second output collimators  91 ,  92  into the first and second output fibers  51 ,  52 , respectively. 
   The optical switch  10  of the present invention makes use of the rotating mechanism  60 , the top stopper  85  and the bottom stopper  86  to move the prism  612  between two precisely located positions. 
   Advantages of the optical switch  10  of the present invention over those of the prior art include the following. First, the driver has a self-latching function. Second, the size of the optical switch is small, since no separately attached latching mechanism is required. Third, the moveable optical component  612  is precisely located in the two different positions. Thus, the insertion loss of the optical switch is minimized. 
   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 fill extent indicated by the broad general meaning of the terms in which the appended claims are expressed.