Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to interface apparatus and, more particularly, is directed toward self-aligning interface apparatus used in testing electrical devices, particularly, microwave devices. 
     2. Description of the Prior Art 
     The electronic testing of microwave equipment, which includes use of multiple industry standard and special purpose microwave interfaces such as Type N, Type F, SMA TNC and BNC, generally requires manually attaching each of the individual test cables to each of these interfaces. Accordingly, such procedures are tedious and time consuming. 
     Although numerous devices have been developed that permit quick connection of the individual cables to interfaces, such devices suffer from the limitation and disadvantage and that each test cable must be individually connected to the interface. According, such devices have met limited success. 
     Self-aligning coaxial cable connectors have been designed to permit “blind” interconnection of coaxial cables with mating connectors that are mounted to stationary housings. U.S. Pat. No. 5,746,617 is an example of such a self-aligning coaxial connector. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a self-aligning interface apparatus used in testing electrical devices, particularly, microwave devices, that does not suffer from the heretofore mentioned limitation and disadvantage of prior art systems. 
     It is another object of the invention to provide an efficient interface apparatus used in testing electrical devices, particularly microwave devices, that permits substantially simultaneous interconnection of multiple connectors on a unit under test with a test apparatus. 
     It is a further object of the present invention to provide an interface apparatus having a plurality of self-aligning coaxial connectors for substantially simultaneous interconnection with a plurality of connectors on a unit under test. 
     According to an embodiment of this invention, an interface apparatus having a plurality of self-aligning coaxial connectors for substantially simultaneous interconnection with a plurality of connectors on a unit under test includes a base member, a first interface and a second interface. The first and second interfaces are spaced apart to receive the unit under test. At least one of the first and second interfaces is slidably movable on the base member for movement into engagement and disengagement with the unit under test that is positioned between the interfaces. At least one of the first and second interfaces has a plurality of self-aligning coaxial connectors that are positioned to interconnect with the plurality of connectors on the unit under test. An urging means is provided for moving the interfaces toward the unit under test for mating engagement of the self-aligning coaxial connectors and the connectors of the unit under test. In operation, the interfaces are spaced apart and a unit under test is placed there between. As the urging means moves one or both of the interfaces into engagement with the unit under test, the self-aligning coaxial connectors mounted to one or both interfaces substantially simultaneously interconnect with the plurality of connectors on the unit under test. Cables connected to the self-aligning connectors are configured to be connected to an analyzer and supply testing the unit under test. Upon completion of the testing, the urging means moves the interfaces apart for disengagement of the self-aligning connectors and the connectors on the unit under test. The interface apparatus is now ready to receive another unit to be tested. 
     The above and other objects, features and advantages of this invention will be more readily apparent from a reading of the following detailed description of various aspects of the invention taken in conjunction with the accompanying drawings. 
     The invention accordingly comprises the steps and apparatus embodying features of construction, combinations of elements and arrangements of parts adapted to affect such steps, as exemplified in the following detailed disclosure, the scope of the invention being indicated in the accompanying claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A fuller understanding of the nature and objects of the present invention will become apparent upon consideration of the following detailed description taken in connection with the accompanying drawings in which: 
     FIG. 1 is a schematic diagram of a test system employing the present invention; 
     FIG. 2 is a perspective view of an interface apparatus embodying the present invention having a plurality of self-aligning coaxial connectors, the interface apparatus being in an open position for receiving a device to be tested; 
     FIG. 3 is a perspective view of the interface apparatus of FIG. 2 in a closed position with the self-aligning coaxial connectors in engagement with a device to be tested; 
     FIG. 4 is a top view showing details of the self-aligning coaxial connectors of FIG. 2; 
     FIG. 5 is a top view showing additional details of the self-aligning coaxial connectors of FIG. 2; 
     FIG. 6 is a top view showing details of the self-aligning coaxial connector of FIG. 2; and 
     FIG. 7 is a perspective view of an alternate embodiment of the interface apparatus in an open position, the interface apparatus having a plurality of rectangularly disposed self-aligning coaxial connectors, a device to be tested being positioned in the interface apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, particularly FIGS. 1-5, there is shown an interface apparatus  10  embodying the present invention that facilitates the interconnection of a device  12  under test with an analyzer  14  and supply  16  for testing the device. As hereinafter described in detail, interface apparatus  10  includes a fixture  18 , a pair of interface members  20 ,  22 , and an urging assembly  24 . A plurality of self-aligning coaxial connectors  26  are mounted to interface members  20  and  22 , the self-aligning coaxial connectors being positioned in substantial alignment with mating connectors  27  on device  12 . FIG. 2 shows interface apparatus  10  in its opened position for receiving device  12 . FIG. 3 shows interface apparatus  10  in its closed position with the connectors  27  being connected to the self-aligning coaxial connectors  26 . Urging assembly  24 , which is mounted to a base  28 , is provided for moving interface apparatus  10  between its opened and closed positions. In the illustrated embodiment, urging assembly  24  is a pneumatically or hydraulically operated device that is controlled by an operator or is automatically actuated. It is to be understood that, in alternate embodiments, urging assembly  24  is a mechanical device that is controlled by an operator or is automatically actuated. The details of fixture  18 , which are best shown in FIGS. 3,  4  and  5 , are discussed below. 
     Referring now to FIGS. 3,  4  and  5 , it will be seen that fixture  18  includes a fixed platform  30  that is adapted to receive interface member  20 . An index pin  32  is provided for registering interface member  20  relative to fixed platform  30 . A slidable platform  34  that is coplanar with fixed platform  30  is operatively connected to urging assembly  24  by means of a rod  36 , for example a threaded rod. Slidable platform  34  is adapted to receive interface member  22 . An index pin  38  is provided for registering interface member  22  relative to slidable platform  34 . 
     First device guides  40   a  and  40   b,  which are adjustable in position on the surface of fixed platform  30  are provided for aligning device  12  with interface member  20 . Second device guides  42   a  and  42   b,  which are adjustable in position on the surface of slidable platform  34 , are provided for aligning device  12  with interface member  22 . Device guides  40   a,    40   b,    42   a  and  42   b  provide a rough alignment of the connectors that are mounted on device  12  and self-aligning coaxial connectors  26  that are mounted to interface members  20 ,  22 . 
     An urging attachment  44  that is fastened to slidable platform  34  is provided for adjustment of the slidable platform  12  relative to urging assembly  24  through the use of fasteners  46 , for example nuts, on threaded rod  36 . Support blocks  48   a  and  48   b  are slidable on guide rails  50   a  and  50   b,  respectively. Support blocks  48   a  and  48   b  are fitted with rail bearings  52   a  and  52   b,  respectively, to facilitate sliding of guide rails  50   a  and  50   b.  A locating channel  54   a  that is formed in support block  48   a  and a locating channel  54   b  that is formed in support block  48   b  are configured to receive interface member  22 . A pair of rear end supports  56   a  and  56   b  that are held in space relationship by a rear support  58  are configured to receive guide rails  50   a  and  50   b.  A pair of front end supports  60   a  and  60   b  that are held in space relationship by a front end support  59  are configured to receive guide rails  50   a  and  50   b.  A pair of front supports  62   a  and  62   b  that are positioned adjacent front end supports  60   a  and  60   b,  respectively, are held in space relationship by a front support  64 . Guide rails  50   a  and  50   b  pass through front supports  62   a  and  62   b.  A locating channel  66   a  that is formed in front support  62   a  and a locating channel  66   b  that is formed in front support  62   b  are configured to receive interface member  20 . A locating channel  68   a  that is formed in front end support  60   a  and a locating channel  68   b  that is formed in front support  60   b  are configured to receive a cable guide  70  (FIG.  2 ). A locating channel  72   a  that is formed in rear end support  56   a  and a locating channel  72   b  that is formed in rear end support  56   b  are configured to receive a cable guide  74  (FIG.  2 ). The geometric relationship of the front end supports  60   a,   60   b  and front supports  62   a,   62   b  is maintained by means of spacers  76 , threaded rod  77  and fasteners  79 . Such an arrangement facilitates easy realignment of the supports as may be needed. 
     As best shown in FIG. 6, each self-aligning coaxial connector  26  includes a housing  80  that is mounted to interface member  22  and fixed against movement relative thereto. Housing  80  has an internal bore  81 , an internal radial flange  82  and an internal radial step  84 . The inside diameter of flange  82  is less than the diameter of step  84  and the diameter of step  84  is slightly smaller than the diameter of bore  81 . A connector  88  that is inserted from the rear of housing  80  has a radial flange  90 . Connector  88  is pushed into housing  80  until connector flange  90  engages housing flange  82 . A washer or ring  92  having a diameter that is greater than the inside diameter of step  84  and less than the diameter of bore  81  is inserted from the rear of housing into engagement with step  84 , step  84  defining a stop for washer  92 . An alignment gap  86  is formed between flange  82  and washer  92 . A spring  94 , for example, a compression spring, having a diameter that is less than the diameter of bore  81  and greater than the inside diameter of washer  92  is inserted from the rear of housing  80  into engagement washer  92 . A retainer  96  is fitted into the rear of housing  80  for retaining spring  94  therein. Retained spring  94  applies a longitudinal or axial spring force against the washer  92 . 
     A coupling collar  98  having an enlarged mouth  100  at a forward end thereof and a plurality of fingers  102  at a rear end thereof is inserted into a front end of housing  80 . Enlarged mouth  100  serves as a lead frusto-conical section or cam surface at the forward end of coupling collar  98 . Fingers  102  grip raised projections  104  that are provided on connector  88  for captively holding collar  98  to connector  88 . A cable  106 , for example a coaxial cable, is connected to connector  88 . 
     The longitudinal or axial spring force that is applied by spring  94  against washer  92  urges the washer toward an initial longitudinal position in engagement with step  84 . In this manner, connector  88  and its attached coupling collar  98  are resiliently supported within stationary housing  80 , in such a manner that connector  88  and collar  98  are provided with freedom of movement in the axial direction relative to stationary housing  80  against the bias of axial spring force. 
     In addition to movement in the axial direction, connector  88  and collar  98  are movable in an orthogonal direction. Radial flange  90  is provided with a predetermined thickness and diameter, and alignment gap  86  is provided with a predetermined depth and diameter so that there is provided sufficient axial clearance for flange  90  to slide freely in the orthogonal directions between radial flange  82  and washer  92 . The predetermined diameters of the radial flange  90  and the alignment gap  86  are such that collar  98  and connector  88  can move a predetermined clearance distance in any orthogonal direction. This construction thereby serves to effectively confine radial flange  90  within alignment gap  86 , while enabling connector  88  freedom of substantially unrestricted orthogonal movement relative to a longitudinal axis  108  of housing  80 , within a predetermined range of movement defined by alignment gap  86 . 
     From the foregoing, it will be realized that collar  98  and connector  88  are permitted to tilt or cant against the bias of spring force to a position in which theoretical centerline of collar  98  and connector  88  is disposed at an oblique angle with respect to an actual centerline of bore  81  of housing  80 . Accordingly, the present invention thus effectively provides collar  98  and connector  88  with freedom of movement in substantially any direction for movement as a “free body” relative to stationary housing  80  in order to facilitate mating engagement while nominally eliminating application of stress or potential energy on connector components in the orthogonal direction. This will become more apparent with respect to the operation of the present invention discussed hereinafter. 
     In a first step in the operation of the present invention, interface apparatus  10  is placed in its opened position shown in FIG.  2 . Next, device  12  is placed on platforms  30  and  34 . It is to be understood that the self-aligning coaxial connectors  26  on interface members  20  and  22  are generally in general alignment with the connectors  27  on device  12 . Next, urging assembly  24  is activated to move interface apparatus into its closed position shown in FIG.  3 . Assuming misalignment between connector  27  and self-aligning coaxial connectors  26 , continued movement of connector  26  into initial mating engagement with connectors  27  serves to engage lead frusto-conical section or cam surface  100  with external diameter connector  27 . This engagement serves to initiate camming action or self-acting deflection of the coupling collar  98  and connector  88  into coaxial alignment with connector  27 . During this mating movement, the spring force applied by spring  94  against washer  92  generally maintains coupling collar  98  in its initial longitudinal position relative to bore  81  and offers no impediment to the radial translation and alignment of the connector  88 . Accordingly, as discussed herein above, the radial translation or orthogonal movement takes place nominally without generating any orthogonal stress or potential energy, or otherwise deforming or preloading of connectors  88  or connectors  27 . This feature advantageously provides for improved performance and reduced wear relative to prior constructions. Continued mating movement of interface member  22  toward device  12  will bring self-aligning coaxial connectors  26  into coplanar engagement with connector  27 . The continued mating movement of interface member  22  toward device  12  serves to deflect coupling collar  98  and connector  88  relative to bore  81  against the bias of the spring force applied by spring  94 . The spring force bears directly upon contact faces of connectors  27  and connector  88  to help ensure that the connectors are electrically unified. This deflection also serves to advantageously compensate for longitudinal tolerances in connectors  88  and  27 . Connectors  88  and  27  thus reach a fully mated position after occurrence of such deflection. 
     In the embodiment shown in FIGS. 2 and 3, connectors  27  are mounted on opposite parallel sides of device  12 . Accordingly, interface members  20  and  22  are in parallel alignment, interface member  20  being stationary and interface member  20  being slidable. In an alternate embodiment shown in FIG. 7, a device  110  to be tested has a plurality of connectors  112  on four sides. In this embodiment, an interface apparatus  114  has a plurality of self-aligning coaxial connectors  116  that are mounted on interface members  118 ,  120 ,  122  and  124 . Interface apparatus  114  is substantially identical in construction and operation to interface apparatus  10 . However, in the embodiment of FIG. 7, all or selected ones of interface members  118 ,  120 ,  122  and  124  are movable relative to device  110  by means of urging assemblies, each of which is substantially identical to urging assembly  24  shown in FIG. 2 for interconnection of self-aligning coaxial connectors  116  and connectors  112 . 
     Thus, the subject invention presents a means of accomplishing mechanical blind mating at relatively low cost, without compromise to RF performance by employing a relatively simple construction using many traditional RF components and eliminating the need for relatively high manufacturing tolerances. Further, this invention presents a means of connection in which freedom of movement in an orthogonal direction is provided to compensate for any misalignment while nominally preventing the generation of any orthogonal preload or stress within the connectors. 
     Since certain changes may be made in the foregoing disclosure without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description and depicted in the accompanying drawings be construed in an illustrative and not a limiting sense.

Technology Category: 3