Self-aligning interface apparatus for use in testing electrical

[0002] 1. Field of the Invention

[0003] The invention relates to interface apparatus and, more particularly, is directed toward self-aligning interface apparatus used in testing electrical devices, particularly, microwave devices.

[0004] 2. Description of the Prior Art

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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:

[0015] FIG. 1 is a schematic diagram of a test system employing the present invention;

[0016] 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;

[0017] 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;

[0018] FIG. 4 is a top view showing details of the self-aligning coaxial connectors of FIG. 2;

[0019] FIG. 5 is a top view showing additional details of the self-aligning coaxial connectors of FIG. 2;

[0020] FIG. 6 is a top view showing details of the self-aligning coaxial connector of FIG. 2; and

[0021] 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.

[0022] 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.

[0023] 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.

[0024] First device guides 40aand 40b,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 42aand 42b,which are adjustable in position on the surface of slidable platform 34, are provided for aligning device 12 with interface member 22. Device guides 40a,40b,42aand 42bprovide 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.

[0025] 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 48aand 48bare slidable on guide rails 50aand 50b,respectively. Support blocks 48aand 48bare fitted with rail bearings 52aand 52b,respectively, to facilitate sliding of guide rails 50aand 50b.A locating channel 54athat is formed in support block 48aand a locating channel 54bthat is formed in support block 48bare configured to receive interface member 22. A pair of rear end supports 56aand 56bthat are held in space relationship by a rear support 58 are configured to receive guide rails 50aand 50b.A pair of front end supports 60aand 60bthat are held in space relationship by a front end support 59 are configured to receive guide rails 50aand 50b.A pair of front supports 62aand 62bthat are positioned adjacent front end supports 60aand 60b,respectively, are held in space relationship by a front support 64. Guide rails 50aand 50bpass through front supports 62aand 62b.A locating channel 66athat is formed in front support 62aand a locating channel 66bthat is formed in front support 62bare configured to receive interface member 20. A locating channel 68athat is formed in front end support 60aand a locating channel 68bthat is formed in front support 60bare configured to receive a cable guide 70 (FIG. 2). A locating channel 72athat is formed in rear end support 56aand a locating channel 72bthat is formed in rear end support 56bare configured to receive a cable guide 74 (FIG. 2). The geometric relationship of the front end supports 60a,60band front supports 62a,62bis 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.