Abstract:
An electrical connector that comprises a pressure surface bearing a first array of electrical contacts. In addition a side-wall has an exterior surface and is physically connected to the pressure surface. The exterior surface bears a second array of electrical contacts, which are electrically connected to the first array of electrical contacts. Additionally, the electrical connector may include a ball screw for pressing the first array into the second array.

Description:
STATEMENT OF GOVERNMENT SUPPORT 
     This invention was made with government support under contract No.: NO1 DC-7-2103 awarded by the National Institute of Health (NIH). The government has certain rights in the invention. 
    
    
     BACKGROUND OF THE INVENTION 
     Percutaneous connectors are, generally speaking, connectors having a first half that is attached to an animal body (typically to the skull) and a second half that can be connected to the first half for transmitting information out of or into the animal body. Unfortunately, when an animal test subject such as a chimpanzee wears the first half, mating the two halves together typically requires anaesthetization of the test subject. This greatly increases the expense of each instance of connecting the two halves in terms of materials, time and test subject health. The anaesthetization must currently be performed because mating the two halves requires some delicate adjustments, for example the careful tightening of a pair of screws. Additionally, it is typical to implant the first half into the skull and permit skull bone tissue to grow into surface irregularities in the portion of the first half touching skull bone. It is very important that little to no force be applied to the first half so that the first half will not be wrenched out of its setting in the skull bone. 
     The design goals described above are particularly difficult to meet in the context of a high-density connector. In order to accommodate a high pin density it is generally desirable to use a sheet of anisotropically conducting material to electrically connect the two connector halves. This material must be compressed with a considerable amount (35-70 lbs) of force, which has complicated the task of coupling the connector halves faced by users of prior art connectors. 
     SUMMARY 
     In a first separate aspect the present invention is an electrical connector that comprises a pressure surface bearing a first array of electrical contacts. In addition a side wall has an exterior surface and is physically connected to the pressure surface. The exterior surface bears a second array of electrical contacts, which are electrically connected to the first array of electrical contacts. 
     In a second separate aspect the present invention is an electrical connector, comprising a first pressure surface bearing a first array of contact pads a second pressure surface bearing a second array of contact pads. In addition a pressure applying mechanism presses the first pressure surface into the second pressure surface. This mechanism includes a ball screw and a manual actuator that permits a user to turn the ball screw to press the first pressure surface into the second pressure surface. 
     The foregoing and other objectives, features and advantages of the invention will be more readily understood upon consideration of the following detailed description of the invention, taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view or a connector according to the present invention in its connected state. 
     FIG. 2 is a perspective view of the connector of FIG. 1, with the two-connector stages separated. 
     FIG. 3 is an exploded perspective view of the connector of FIG.  1 . 
     FIG. 4 is a cross-sectional view of the connector of FIG. 1 taken along line  4 — 4  of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of an easily mated, compact connector  10 , in this instance a percutaneous connector, includes an lower connector stage  12 , which is adapted for implantation into an animal or human host. A purely ex vivo upper connector stage  14  attaches to a lower connector stage  12 . A signal cable  15  enters the ex vivo portion through an aperture  16  in a handle  18 . After extending through the handle  18  a set of individual wires  20  from signal cable  15  are connected to a flex circuit  22  at a set of wire contact points  24 . A set of traces  26 , connect wire contact points  24  to a set of pressure contact points  28 . When connector  10  is in its connected state, pressure contact points  28  press against a sheet of elastomeric, anisotropically conductive material  29  that electrically connects them to a set of implanted portion pressure contact points  30 . Anisotropically conductive material  29  is preferably Fujipoly type WBC. Information on how to obtain this material is available from the Internet site www.fujipoly.com. The lower connector stage  12  is preferably made of a material, such as titanium, having good biocompatibility. The upper connector stage  14  is made of high strength stainless steel. It is desirable, however, that the upper connector stage  14  have a yield strength below that of the lower connector stage  12 , so that in the event of failure due to over tightening or a blow to the unit the upper connector stage  14  will give way before the lower connector stage  12 , to avoid greater damage to the test subject or patient. 
     The advantages of this portion of connector  10  may now be evident to skilled persons. Because wires  22  are brought to the exterior side-walls of flex circuit  22  they are not routed through the center top of ex vivo portion  14 . This permits the space in this area to be used for the pressure-applying and latching portions of connector  10 , rather than to accommodate signal-bearing media, such as wires. 
     More specifically, the center is occupied by a ball screw  40 , which is used to apply pressure between contacts  28  and contacts  30 . The ball screw  40  includes a core  42 , a set of bail bearings  44 , a ball screw handle  46  and a latch  48 . In addition a claw ring  50  mates with partially implanted portion  12  by way of a set of three leg claws  52  that fit through a matching set of slots  54  and are retained underneath a rim  56 . As the exterior of the claw ring  50  is accessible to an operator, an operator can directly rotate claw ring  50  to place it in the position shown in FIG. 1 with claws  52  retained under rim  56 . In an alternative preferred embodiment, claws  52  are extend clockwise so that claw ring  50  is rotated in the same direction (clockwise) as is handle  46  in the process of connecting upper connector stage  14  to lower connector stage  12 . 
     The core  42  defines an inner ball bearing race in the form of seven grooves  60 , each one briefly extending along the course of a shallow helix. The claw ring  50  defines an outer ball bearing race in the form of an inner circular groove  62 . 
     When connector  10  is in its loosened state, for attaching and detaching portion  12  to portion  14 , the handle  46  and latch  48  are turned clockwise by a one-quarter rotation relative to handle  18 . To apply pressure between contacts  28  and  30  handle  46  is moved in a counter-clockwise direction until it rests over handle  18 . When the ball screw handle  46  moves the core  42  clockwise, the set of ball bearings  44  positioned between inner race  60  and outer race  62  are caused to rotate and to move in a clockwise direction alone inner race  60 . The helical nature of race  60  causes core  42  to move downwardly relative to outer race  62 . As claw ring  50 , and therefore outer race  62 , is fixed in place relative to lower connector stage  12  this action squeezes a pressure fixture  12  and thereby contacts  28  downwardly to engage contacts  30 . The rotation of core  42  is facilitated by a bottom set of ball bearings  80 , held in place by a bottom race  82 . 
     Because of the great mechanical advantage achieved by the ball screw  40 , greater than 50 lbs of pressure may be realized by the simple one-eighth turn of the handle  46  described above. This greatly facilitates the formation of electrical contacts using anisotropically conductive material  29 . 
     After an operator places claws  52  under rim  56  as described above, he rotates the handle  46  and latch  48  clockwise to effect the tightening described above. In the tightened position shown in FIG. 1, the latch  48  is retained by a catch element  86  (shown in FIG.  2 ). 
     The terms and expressions which have been employed in the foregoing specification are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.