Patent Publication Number: US-10309552-B2

Title: Multi-stage rotary overtravel stop

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. application Ser. No. 14/580,401, filed Dec. 23, 2014, which claims the benefit of U.S. Provisional Application Ser. No. 61/921,160, filed Dec. 27, 2013, the entire contents of both are hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a joint, and in particular to a stop for a rotary joint that can be used in medical devices. 
     BACKGROUND OF THE INVENTION 
     Surgical lights have been used in operating rooms to provide increased light to a specific area of the room. Likewise, other wired devices, such as monitors, speakers, joysticks, keyboards and cameras, have been used in operating rooms to provide surgical information to a surgeon or other person in the operating room (e.g., images from a camera or patient vital information). Moreover, booms holding IVs, shelves, electrical outlets and/or gas outlets are used to assist medical personnel in helping patients. Such apparatuses receive and/or provide signals and power and/or gas to and/or from various supports mounted or provided in the operating room, thereby requiring conduits (including cables (e.g., electrical power, electrical data and fiber optic) and/or gas hoses) to extend through supports for such devices to the devices. 
     SUMMARY OF THE INVENTION 
     The present invention, according to one aspect, is directed to a rotary joint for use in a medical application including a first linkage having a first abutment, a second linkage rotatably connected to the first linkage, with the second linkage having a second abutment, and an idler member having a third abutment at a top side thereof and a fourth abutment at a bottom side thereof. At least one conduit extends through the first linkage and the second linkage. The first linkage has at least one connector being rotatably fixed to the second linkage for allowing the first linkage to rotate relative to the second linkage. The idler member is free to rotate relative to the first linkage and the second linkage until the first abutment of the first linkage abuts the third abutment of the idler member and until the second abutment of the second linkage abuts the fourth abutment of the idler member. The first linkage is able to rotate relative to the second linkage at a maximum angular displacement that is greater than 360°. The first linkage, the second linkage and the idler member all rotate relative to each other about a single axis. 
     Another aspect of the present invention includes providing a medical device assembly including a first member having a first abutment, a second member rotatably connected to the first member, with the second member having a second abutment, and an idler member having a third abutment at a top side thereof and a fourth abutment at a bottom side thereof. At least one conduit extends through the first member and the second member. The first member is rotatably fixed to the second member. The idler member is free to rotate relative to the first member and the second member until the first abutment of the first member abuts the third abutment of the idler member and until the second abutment of the second member abuts the fourth abutment of the idler member. The first member, the second member and the idler member all rotate relative to each other about a single axis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments of the present invention are illustrated by way of example and should not be construed as being limited to the specific embodiments depicted in the accompanying drawings, in which like reference numerals indicate similar elements. 
         FIG. 1  illustrates a perspective view of a medical device assembly according to the invention. 
         FIG. 2  is a first exploded perspective view of a surgical light camera having a first rotary joint with a multi-stage rotary overtravel stop according to the invention. 
         FIG. 3  is a second exploded perspective view of the surgical light camera having the first rotary joint with a multi-stage rotary overtravel stop according to the invention, with  FIG. 3  being inverted relative to the position of the surgical light camera having the first rotary joint shown in  FIG. 2 . 
         FIG. 4  is a cross-sectional view of an idler member, the first abutment area and the second abutment area of the first rotary joint with a multi-stage rotary overtravel stop according to the invention. 
         FIG. 4A  is a cross-sectional view of the first rotary joint with a multi-stage rotary overtravel stop according to the invention having multiple idler members. 
         FIG. 5  illustrates a range of motion of the idler member relative to a bezel of the first rotary joint with a multi-stage rotary overtravel stop according to the invention. 
         FIG. 6  illustrates a range of motion of the idler member relative to a light housing of the first rotary joint with a multi-stage rotary overtravel stop according to the invention. 
         FIG. 7  is a top view of an idler member of a second rotary joint with a multi-stage rotary overtravel stop according to the invention. 
         FIG. 8  is a cross-sectional view of the idler member of the second rotary joint taken along substantially line VIII-VIII of  FIG. 7 . 
         FIG. 9  is a perspective view of a third rotary joint with a multi-stage rotary overtravel stop according to the invention. 
         FIG. 10  is a side view of the third rotary joint with the multi-stage rotary overtravel stop according to the invention. 
         FIG. 11  is a perspective view of a second medical device assembly according to the invention. 
     
    
    
     The specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting. 
     DETAILED DESCRIPTION 
     The reference number  10  ( FIG. 1 ) generally designates a medical device assembly of the present invention. The medical device assembly  10  is configured to be positioned within a room (e.g., operating room) and includes at least one wired medical unit  12  configured to provide information to the medical personnel in the room and/or assist the medical personnel in the room perform various functions. In the illustrated example, the medical device assembly  10  includes a plurality of wired medical units  12  in the form of a surgical light  12   a  configured to provide increased light to a specific area of the room and a monitor  12   b  for providing surgical information to a surgeon or other person in the operating room (e.g., images from a camera or patient vital information). 
     The illustrated surgical light  12   a  is connected to a ceiling attachment bracket  16  by a first arm assembly  18  and the monitor  12   b  is connected to the ceiling attachment bracket  16  by a second arm assembly  20 . It is contemplated that the medical device assembly  10  can include any number of arm assemblies and wired medical units  12 , including only one arm assembly and wired medical unit  12 , and that each arm assembly can include a plurality of wired medical units  12  supported therefrom. While the medical device assembly  10  is illustrated as being connected to a ceiling, the medical device assembly  10  can be directly connected to a suspension system connected to a wall or ceiling of the operating room, can be connected to a further arm assembly (not shown) directly connected to a wall or ceiling of the operating room, or can be directly or indirectly connected to a movable assembly located within the operating room. 
     In the illustrated example, the first arm assembly  18  and the second arm assembly  20  can be selectively moved and positioned to allow for a person to position the wired medical units  12  in a desired location. The illustrated first arm assembly  18  and the second arm assembly  20  each include a plurality of arms  22  and joints for adjusting a position of the medical units  12 . For example, the first arm assembly  18  and the second arm assembly  20  can each include a first arm  24  connected to the ceiling attachment bracket  16  by a shoulder joint  26  and a second arm  28  connected to the first arm  24  by an elbow joint  30 , with the medical unit  12  being connected to the second arm  28  by a wrist joint  32 . At least one conduit  34  extends through the ceiling attachment bracket  16 , the shoulder joint  26 , the first arm  24 , the elbow joint  30 , the second arm  28  and the wrist joint  32  to the medical units  12  to provide and/or receive signals and power to and/or from the medical units  12 . In the illustrated example, the at least one conduit is electrical wiring. 
     In order to allow a full range of motion of the first arm assembly  18  and the second arm assembly  20  so that the wired medical units  12  can be selectively located or positioned, the wired medical units  12  have several joints  26 ,  30 ,  32 . In order to prevent potentially damaging twisting of the at least one conduit  34  within the arm assemblies  18 ,  20  and the wired medical units  12 , several of the joints of the medical device assembly  10  can each include a rotary joint  100  with a multi-stage rotary overtravel stop to prevent unlimited rotation of the joints having the at least one conduit  34  extending therethrough. Furthermore, portions of the medical units  12  can have the rotary joint  100  with the multi-stage rotary overtravel stop to prevent unlimited rotation of the joints to thereby prevent potentially damaging twisting of the at least one conduit  34 . 
       FIGS. 1-3  illustrate a first embodiment of the rotary joint  100  with a multi-stage rotary overtravel stop for use with the illustrated surgical light  12   a . In the illustrated example, the surgical light  12   a  can include a surgical camera assembly  36  having a camera housing  40  rotatably connected to a light housing  38  of the surgical light  12   a . Surgical camera assemblies  36  for use with surgical lights  12   a  are well known to those skilled in the art. As illustrated in  FIGS. 1-3 , the surgical camera assembly  36  is connected to the light housing  38  using the rotary joint  100 . The rotary joint  100  with the multi-stage rotary overtravel stop limits the rotation of the surgical camera assembly  36  relative to the light housing  38  (e.g., to a range of motion greater than 360°) to thereby prevent potentially damaging twisting of the at least one conduit  34 . 
     The rotary joint  100  as illustrated in  FIGS. 1-3  includes a first member in the form of a bezel  104  connected to the light housing  38  of the surgical light  12   a , a second member in the form of the camera housing  40  and an idler member  106 . The bezel  104  is annular or disc-shaped and extends outwardly from a light emitting area  108  of the surgical light  12   a . The bezel  104  has a front face  114  including a first abutment area  110  having a first abutment  112  for limiting or stopping rotation of the idler member  106 . The first abutment area  110  includes a first circular recess  116  defined by an outer cylindrical wall  118  and a flat bottom wall  120  oriented transversely to one another. The first abutment  112  is located within the first circular recess  116  and extends inwardly from the outer cylindrical wall  118  and the downwardly from flat bottom wall  120  as illustrated in  FIG. 2 . The first abutment  112  is substantially trapezoidal having a radially outward longest edge  122  connected to the outer cylindrical wall  118  of the first circular recess  116 , a radially inward smallest edge  124  opposite the longest edge  122 , a first abutment first contact edge  126  and a second abutment second contact edge  128 . As illustrated in  FIG. 2 , the first circular recess  116  is surrounded by an outer rotary cylindrical ridge  130  defining the outer cylindrical wall  118 . The ridge  130  has a plurality of openings  132  therein configured to receive post-like projections  134  extending outwardly from the camera housing  40  to connect the camera housing  40  to the bezel  104 . 
     The illustrated camera housing  40  engages with the bezel  104  so as to rotate relative thereto. The camera housing  40  has a bottom face  136  including a second abutment area  138  with a second abutment  140  for limiting or stopping rotation of the idler member  106 . The second abutment area  138  includes a second circular recess  142  defined by an outer cylindrical wall  144  and a flat bottom wall  146  oriented transversely to one another. The second abutment  140  is located within the second circular recess  142  and extends inwardly from the outer cylindrical wall  144  and outwardly from the flat bottom wall  146 . The second abutment  140  is substantially trapezoidal having a radially outward longest edge  148  connected to the outer cylindrical wall  144  of the second circular recess  142 , a radially inward smallest edge  150  opposite the longest edge  148 , a second abutment first contact edge  152  and a second abutment second contact edge  154 . As illustrated in  FIG. 3 , the second circular recess  142  is surrounded by an outer rotary cylindrical ridge  156  defining the outer cylindrical wall  144 . The ridge  156  has the post-like projections  134  extending outwardly therefrom. The projections  134  extend into the openings  132  in the outer rotary cylindrical ridge  130  of the bezel  104 . The outer rotary cylindrical ridge  130  of the bezel  104  rotates freely relative to the outer cylindrical ridge  156  of the camera housing  40  to allow the camera housing  40  to freely rotate relative to the bezel  104 . 
     In the illustrated example, the idler member  106  is captured between the bezel  104  and the camera assembly  36  to limit rotation of the camera housing  40  of the camera assembly  36  relative to the bezel  104  and the light housing  38 . The idler member  106  includes a disc  200  having a top surface  202  and an oppositely facing bottom surface  204 . A third abutment  206  extends axially from the top surface  202  and a fourth abutment  208  extends axially from the bottom surface  204 . The third abutment  206  is similar in configuration to the first abutment  112 , and is substantially trapezoidal having a peripheral longest edge  210 , a radially inward smallest edge  212  opposite the longest edge  210 , a third abutment first contact edge  214  and a third abutment second contact edge  216 . The fourth abutment  208  is substantially trapezoidal having a peripheral longest edge  220 , a radially inward smallest edge  222  opposite the longest edge  220 , a fourth abutment first contact edge  224  and a fourth abutment second contact edge  226 . 
     The illustrated idler member  106  is captured between the bezel  104  and the camera assembly  36 .  FIG. 4  illustrates a cross-sectional view of the idler member  106 , the first abutment area  110  and the second abutment area  138  (along with illustrating the outer rotary cylindrical ridge  130  of the bezel  104  and the outer rotary cylindrical ridge  156  of the camera housing  40 ). As illustrated in  FIG. 4 , the third abutment  206  is located in the first circular recess  116  of the first abutment area  110 , with a top surface  300  of the third abutment  206  abutting and riding on the flat bottom wall  120  of the first circular recess  116 . Likewise, a bottom surface  302  of the first abutment  112  rides on the top surface  202  of the disc  200  of the idler member  106 . Furthermore, the fourth abutment  208  is located in the second circular recess  142  of the second abutment area  138 , with a bottom surface  304  of the fourth abutment  208  abutting and riding on the flat bottom wall  146  of the second circular recess  142 . Likewise, a top surface  306  of the first abutment  140  rides on the bottom surface  204  of the disc  200  of the idler member  106 . 
       FIG. 5  illustrates the range of motion of the idler member  106  relative to the bezel  104 .  FIG. 5  is a top view of the first abutment area  110  with the flat bottom wall  120 , the outer cylindrical wall  118  and the first abutment  112 . The third abutment  206  moves about a center of the first abutment area  110  within the first circular recess  116  of the first abutment area  110 . As illustrated in  FIG. 5 , the third abutment  206  can move clockwise along line  400  until the third abutment first contact edge  214  of the third abutment  206  abuts against the first abutment first contact edge  126  (in position  206 ′ as shown in dotted lines), thereby preventing further rotation of the third abutment  206 . Likewise, the third abutment  206  can move counter-clockwise along line  402  until the third abutment second contact edge  216  of the third abutment  206  abuts against the second abutment second contact edge  128  (in position  206 ″ as shown in dotted lines), thereby preventing further rotation of the third abutment  206 . A maximum angular distance of rotation the third abutment  206  within the first circular recess  116  of the first abutment area  110  of the bezel  104  is equal to 360° minus a first angular width  404  (in degrees) of the first abutment  112  and minus a third angular width  406  (in degrees) of the third abutment  206 . 
       FIG. 6  illustrates the range of motion of the idler member  106  relative to the camera assembly  36 .  FIG. 6  shows a bottom view of the second abutment area  138  with the flat bottom wall  146 , the outer cylindrical wall  144  and the second abutment  140 . The fourth abutment  208  moves about a center of the second abutment area  138  within the second circular recess  142  of the second abutment area  138 . As illustrated in  FIG. 6 , the fourth abutment  208  can move clockwise along line  408  until the fourth abutment first contact edge  224  of the fourth abutment  208  abuts against the second abutment first contact edge  152  (in position  208 ′ as shown in dotted lines), thereby preventing further rotation of the fourth abutment  208 . Likewise, the forth abutment  208  can move counter-clockwise along line  410  until the fourth abutment second contact edge  226  of the fourth abutment  208  abuts against the second abutment second contact edge  154  (in position  208 ″ as shown in dotted lines), thereby preventing further rotation of the fourth abutment  208 . A maximum angular distance of rotation the fourth abutment  208  within the second circular recess  142  of the second abutment area  138  of the camera assembly  36  is equal to 360° minus a second angular width  412  (in degrees) of the second abutment  140  and minus a fourth angular width  414  (in degrees) of the fourth abutment  208 . 
     In the illustrated embodiment, the idler member  106  allows the camera assembly  36  to rotate relative to the light housing  38  greater than 360° to allow for a wide range of angles, but not more than 720° to prevent unlimited rotation of the camera assembly  36  to thereby prevent potentially damaging twisting to the at least one conduit  34  leading from the light housing  38  to the camera assembly  36 . The maximum angular distance of rotation of the camera assembly  36  relative to the light housing  38  is 720° minus the first angular width  404  (in degrees) of the first abutment  112 , the second angular width  412  (in degrees) of the second abutment  140 , the third angular width  406  (in degrees) of the third abutment  206 , and the fourth angular width  414  (in degrees) of the fourth abutment  208 . Accordingly, the maximum angular distance of rotation of the camera assembly  36  relative to the light housing  38  can be adjusted by altering the angular widths of the first abutment  112 , the second abutment  140 , the third abutment  206  and/or the fourth abutment  208 . It is also contemplated that multiple idler members  106 ,  106 ′ (with abutments  206 ′ and  208 ′) could be used (see  FIG. 4A ), with the maximum angular distance of rotation of the camera assembly  36  relative to the light housing  38  being calculated as 360° plus 360° times the number of idler members  106  minus the angular widths of all of the abutments. 
     The illustrated idler member  106  is free to rotate relative to the camera assembly  36  and the light housing  38 . In the illustrated embodiment, the camera assembly  36 , the light housing  38  and the idler member  106  rotate relative to each other about a single axis  475  (see  FIG. 4 ). Moreover, the idler member  106  is maintained in position within the first circular recess  116  of the first abutment area  110  and the second circular recess  142  of the second abutment area  138  through engagement with the first abutment  112 , the flat bottom wall  120 , and the outer cylindrical wall  118  of the first abutment area  110  and the second abutment  140 , the flat bottom wall  146 , and the outer cylindrical wall  144  of the second abutment area  138 . However, it is contemplated that the idler member  106  could be maintained in position within the first circular recess  116  of the first abutment area  110  and the second circular recess  142  of the second abutment area  138  through additional structures. For example, a post (not shown) could extend from the camera assembly  36  and/or the bezel  104  of the light housing  38  through a center opening  450  in the disc  200  of the idler member  106 . The post could maintain the idler member  106  is a set axial and/or radial position, but allow the idler member  106  to freely rotate about the post. 
     While an illustrated bezel  104 , idler member  106  and camera assembly  36  are shown, the bezel  104 , idler member  106  and camera assembly  36  could have other configurations. For example, while the abutments are shown and illustrated as being substantially trapezoidal, the abutments could have other shapes. In this regard, each abutment could include a pair of walls or pillars that form each abutment edge for each abutment. Each abutment could also be rectangular, circular or take any other shape. The angular widths in degrees of the abutments in any form is the angular distance wherein an abutment on the idler member  106  cannot travel within one of the circular recesses. In the illustrated example, the at least one conduit  34  extends through the center opening  450  in the disc  200  of the idler member  106  (and could extend through any post through the center opening  450 ). However, it is contemplated that the at least one conduit  34  could extend between the camera assembly  36  and the light housing  38  outside of the idler member  106 . 
     The reference numeral  106   a  ( FIGS. 7-8 ) generally designates another embodiment of the present invention, which includes a second embodiment for the idler member. The second embodiment of the idler member  106   a  includes a damping member in the form of springs to damp impact of the abutments. The second embodiment of the idler member  106   a  includes a disc  200   a  having a top surface  202   a  and an oppositely facing bottom surface  204   a . A third abutment  206   a  extends axially outwardly from the top surface  202   a  and a fourth abutment  208   a  extends axially outwardly from the bottom surface  204   a.    
     As illustrated in  FIGS. 7 and 8 , the third abutment  206   a  is a block  502  configured to angularly slide within a third abutment slot  504 . The third abutment  206   a  includes an inner groove  506  on a radially inward facing surface  508  and an outer groove  510  on a radially outward facing surface  512 . A pair of aligned tongues  514  extend radially into the third abutment slot  504  and into the inner groove  506  and the outer groove  510  to allow the third abutment  206   a  to slide within and be retained within the third abutment slot  504 . The third alignment slot  504  has a first side end wall  516  and a second side end wall  518 , with the first side end wall  516  and the second side end wall  518  limiting angular movement of the third abutment  206   a  relative to the disc  200   a . A first side spring  520  extends through an opening in the first side end wall  516  to contact a third abutment first contact edge  214   a  and a second side spring  522  extends through an opening in the second side end wall  518  to contact a third abutment second contact edge  216   a . The first side spring  520  and the second side spring  522  damp the impact of the third abutment  206   a  with the first abutment  112 . 
     In the illustrated embodiment, a bottom view of the idler member  106   a  is a mirror image of the idler member  106  shown in  FIG. 7 . Accordingly, the fourth abutment  208   a  is a block  524  configured to angularly slide within a fourth abutment slot  526 . The fourth abutment  208   a  includes an inner groove  528  on a radially inward facing surface  530  and an outer groove  532  on a radially outward facing surface  534 . A pair of aligned tongues  536  extend radially into the fourth abutment slot  526  and into the inner groove  528  and the outer groove  532  to allow the fourth abutment  208   a  to slide within and be retained within the fourth abutment slot  526 . The fourth abutment slot  526  includes end walls for limiting angular movement of the fourth abutment  208   a  relative to the disc  200   a  and springs to damp the impact of the fourth abutment  208   a  with the second abutment  140 . It is contemplated that any other spring and/or damping member or system could be substituted for any of the springs (e.g., dashpot, elastomer, gel pack). Moreover, any of the abutments could have similar springs or damping members for damping impacts of abutments with other abutments. 
     The reference numeral  100   b  ( FIG. 9 ) generally designates another embodiment of the present invention, which includes a second embodiment for the rotary joint. The second embodiment of the rotary joint  100   b  is illustrated as being used with the second arm assembly  20 . The second embodiment of the rotary joint  100   b  is illustrated as being located adjacent the wrist joint  32  of the second arm assembly  20 . The rotary joint  100   b  is provided between an extension  603  extending from the wrist joint  32  and a monitor holding bracket  600  holding the monitor  12   b . The monitor holding bracket  600  holds the monitor  12   b  and allows the monitor  12   b  to pivot about the bracket  600  at end points  602  of the monitor holding bracket  600 . A handle  604  connected to the monitor  12   b  is used to selectively move the monitor  12   b . In  FIG. 9 , a sleeve  606  located over the extension  603  and portions of the monitor holding bracket  600  are removed for clarity. 
     In the illustrated example, the extension  603  includes a support cylinder  610  connected to the wrist joint  32 . The support cylinder  610  includes an upper larger cylindrical portion  612 . A lower smaller cylindrical portion  614  extends from the monitor holding bracket  600  and into the upper larger cylindrical portion  612 . It is contemplated that the lower smaller cylindrical portion  614  could be rotatable relative to the upper larger cylindrical portion  612  or could be rotatably connected to the monitor holding bracket  600  to allow the monitor holding bracket  600  to rotate relative to the extension  603 . A first abutment  112   b  in the form of a rectangular block is connected to the upper larger cylindrical portion  612  and extends downwardly therefrom over and radially spaced from the lower smaller cylindrical portion  614 . 
     The illustrated monitor holding bracket  600  is rotatably connected to the extension  603 . The monitor holding bracket  600  includes an upwardly extending cylinder  616  accepting the lower smaller cylindrical portion  614  of the support cylinder  610  of the extension  603  therein. As illustrated in  FIG. 9 , the upwardly extending cylinder  616  of the monitor holding bracket  600  includes a disc-shaped plate  618  extending radially inwardly below the upper larger cylindrical portion  612 , with a radially inner edge  620  surrounding and being closely adjacent or abutting the lower smaller cylindrical portion  614  of the support cylinder  610 . A second abutment  140   b  in a form of a rectangular block extends radially inwardly from an inner cylindrical surface  622  of the upwardly extending cylinder  616  and axially from the disc-shaped plate  618  towards the upper larger cylindrical portion  612  of the support cylinder  610  of the extension  603 . 
     In the illustrated example, an idler member  106   b  ( FIG. 10 ) surrounds the lower smaller cylindrical portion  614  of the support cylinder  610  of the extension  603 . The idler member  106   b  is disc-shaped and includes a disc  200   b  in the form of a ring and includes an inverted T-shaped abutment member  624  extending radially outwardly from an outer cylindrical surface  626  of the idler member  106   b . The disc  200   b  is configured to freely rotate about the lower smaller cylindrical portion  614  of the support cylinder  610  of the extension  603  while riding on the disc-shaped plate  618 . 
     The illustrated idler member  106   b  limits rotation of the extension  603  relative to the monitor holding bracket  600 . The inverted T-shaped abutment member  624  of the idler member  106   b  includes an upper leg  630  defining a third abutment  206   b  and a foot  632  defining a fourth abutment  208   b . The third abutment  206   b  includes a third abutment first side edge  634  configured to abut a first abutment first side edge  636  of the first abutment  112   b  during rotation of the idler member  106   b  in a first direction and a third abutment second side edge  638  configured to abut a first abutment second side edge  640  of the first abutment  112   b  during rotation of the idler member  106   b  in a second direction opposite to the first direction, thereby limiting rotation of the idler member  106   b  relative to the extension  603 . The fourth abutment  208   b  includes a fourth abutment first side edge  642  configured to abut a second abutment first side edge  644  of the second abutment  140   b  during rotation of the idler member  106   b  in a first direction and a fourth abutment second side edge  646  configured to abut a second abutment second side edge  648  of the second abutment  140   b  during rotation of the idler member  106   b  in a second direction, thereby limiting rotation of the idler member  106   b  relative to the monitor holding bracket  600 . 
     In the illustrated example, the idler member  106   b  of the second embodiment of the rotary joint  100   b  limits rotation of the monitor  12   b  relative to the second arm assembly  20 . The idler member  106   b  allows more than 360° of rotation, but not unlimited rotation, thereby preventing potentially damaging twisting to the at least one conduit  34   b  extending through the second arm assembly  20  and the monitor holding bracket  600  to the monitor  12   b.    
       FIG. 11  illustrates a second medical device assembly  1000  according to the invention. The second medical device assembly  1000  includes a base  1005  connected to a ceiling, with the base  1005  having a first arm assembly  1001  and a second arm assembly  1003  connected thereto that can be selectively moved and positioned to allow for a person to position respective medical units  12   c . The first arm assembly  1001  and the second arm assembly  1003  each include a first arm  1022  rotatably connected to the base  1005  at a rotary joint  1020 , a second arm  1024  rotatably connected to the first arm  1022  at a rotary joint  1020  and a post  1026  rotatably connected to the second arm  1026  at a rotary joint  1020 . At least one conduit (e.g., electrical power cables  1030 , gas lines  1040  and data cables  1050 ) pass from the base  1005 , through the first arm assembly  1001  and the second arm assembly  1003  and to the medical units  12   c  to provide electricity, data and/or gas to the medical units  12   c . All of the rotary joints  1020  can comprise the rotary joints  100  and  100   b  of the present invention as described above to allow the elements on each side of the rotary joint  1020  to have a maximum angular displacement that is greater than 360°. 
     The medical units  12   c  are utilized to provide electricity, data and/or gas to support the functioning of various types of medical equipment utilized in a patient care area. More specifically, the medical units  12   c  of the second medical device assembly  1000  each include a service head  1006  connected to the post  1026 . Each service head  1006 , in the illustrated embodiment, includes electrical outputs or outlets  1010  connected to the electrical power cables  1030  and/or other outputs or outlets  1012  for video or data communication connected to the electrical data cables  1050  or gas outputs for supplying gas from the gas lines  1040 . In the illustrated embodiment, the service heads  1006  include a pair of rods or rails  1008  which support at least one adjustable shelf  1002 . The adjustable shelf  1002  can support medical apparatus such as a fluid pump (not shown) and/or an IV support pole system  1004 . Such a service head arrangement is the FLEXIS® system as sold by Stryker Corporation of Kalamazoo, Mich. 
     Although the present invention has been described with reference to specific exemplary embodiments, it will be recognized that the invention is not limited to the embodiments described, but can be practiced with modification and alteration within the spirit and scope of the appended claims. For example, the rotary joints  100  and  100   b  of the present invention could be used in any joint in any application outside of the medical field for allowing more than 360° of rotation, but not unlimited rotation. Moreover, even though the at least one conduit  34  is illustrated as extending through the arm assemblies and through the idler members, it is contemplated that the at least one conduit  34  could go around the idler member and/or possibly around the arms, brackets and/or joints. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. 
     Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.