Abstract:
An improved radiation resistant door seal which is comprised of a door member and frame member. The door member comprises a plurality of flange members and a conductive blade which extends lengthwise and is insertable within a channel formed within the frame member. The channel within the frame member further comprises side walls with bowed contact members on each side of the walls to engagingly capture the blade when inserted therein. A plurality of finger-like contact members is positioned within the door member such to provide enhanced shielding and electrical contact areas to thwart radiation penetration.

Description:
REFERENCE TO PENDING APPLICATIONS 
   This application is not related to any pending applications. 
   REFERENCE TO MICROFICHE APPENDIX 
   This application is not referenced in any microfiche appendix. 
   BACKGROUND OF THE INVENTION 
   This invention relates to the construction of radiation shielded enclosures of the type designed to have an interior that may be relatively isolated from radio interference and other radiation. The invention is particularly directed to the construction of door joints for such enclosures for the purpose of increasing the resistance to radiation penetration through the joints between the edges of the door and its frame. 
   U.S. Pat. No. 4,817,337 (hereinafter referred to as the &#39;337 patent) issued on Apr. 4, 1989 to Lahita shows a radiation resistant door seal. It is to be noted that the Lahita of the &#39;337 patent is the inventor of the present invention. The present application advances the art beyond that disclosed in the &#39;337 patent by teaching, disclosing and claiming resilient arch shaped contact members absent the bowed forward section and edge sections associated with the resilient contact members required of the &#39;337 patent. Further, the instant invention provides, discloses and claims a third arch-like member attached to a door section which in combination provides for additional electrical contact areas to that offered in the &#39;337 patent as well as obviating a deficiency in the &#39;337 patent which requires contact members to compress or otherwise displace in a direction in opposition to shielding pressure induced by a door blade when inserting a rigid blade member between the contact members. Succinctly stated, the enhancements to the art taught by the instant application advance the teachings of the &#39;337 patent by providing additional shielding and electrical contact surfaces. 
   Shielding effectiveness requirements are ever increasing such that standards that were acceptable in the past may be totally unacceptable today. For example, the door joint must be as resistant to radiation leakage as the enclosure itself. 
   A door and frame construction herein disclosed provides 360 degree environmental protection against air, sound and dust and radiation (non-ionizing) protection about the periphery of the door. Tapering of channel side walls to complement the different contact sections increases surface contact, reduces friction, and improves radiation shielding via the metal-to-metal contacting between contact spring fingers. A knife-edge shoulder in each opposed channel side wall increases contact with its contact plate, forms and cooperates to hold its contact plate in the channel. Further, tapered side walls reduce friction forces resisting door closure and increase conductive paths by affording a larger contacting surface of the contact plates with the blade. 
   Consequently, it is an object of the instant invention to provide a door and frame construction which provides 360 degrees of environmental protection against air, sound, dust and radiation protection around the periphery of the door. 
   It is a further object of the instant invention to provide, teach and claim the tapered channel walls to compliment different contact sections which reduce friction and improve radiation shielding by a metal-to-metal contacting between spring fingers. 
   Another object of the instant invention is to provide, teach and claim a knife-edge shoulder in each opposed channel on the frame member which biases contact members rearwardly when blade-like structure is inserted between contact members and thereby further easing/orienting; door closing sealing. 
   Yet it is another object of the instant invention to teach an improved radiation resistant door seal which provides tapered sidewalls to reduce friction, forces resistant door closure and increase conductive paths by affording a larger contacting surface of contact plates with an insertion blade. 
   An additional object of the instant invention is to teach and claim an improved radiation resistant door seal which facilitates contact member directional compression in a direction of that taught by the &#39;357 patent. 
   Other objects and further scope of the applicability of the present invention will become apparent from the detailed description to follow, taken in conjunction with the accompanying drawings wherein like parts are designated by like reference numerals. 
   BRIEF SUMMARY OF THE INVENTION 
   A radiation resistant enclosure comprising a door member hingedly fixed to a frame member having a doorway adjacent edge portions of the members being electrically conductive, one member including a conductive channel extending lengthwise and having a back wall and a pair of side walls and the other member including an arched contact plate, a plurality of flange members and a conductive blade extending lengthwise and insertable within said channel, and a pair of elongated metal plates for engaging one respective side wall in said channel and the blade to establish good electrical contact therebetween, characterized in that said side walls incline inwardly towards one another whereby to describe a truncated edge-shaped cross-section including an interior shoulder and an elongated interior chamber adjacent the back wall, and each plate has opposite edges with a planar portion engaging the side wall of said chamber and the shoulder, a bowed forward section extending from the planar portion engaging the side wall adjacent to the opening to said channel, and a bowed rearward section extending from the other edge and a bowed central section connecting said sections and adapted to engage the blade. 

   
     DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a portion of a door for a radiation resistant structure and a portion of the frame of the enclosure against which the front edge of the door closes, the door being shown in a slightly open position. 
       FIG. 2  is a horizontal section of the two edge portions of the door and frame with the door in fully closed position. 
       FIG. 3  is a vertical section taken on line  3 — 3  of FIG.  2 . 
       FIG. 3A  is a vertical section taken on line  3 A— 3 A of FIG.  2 . 
       FIG. 4  is a view partially in section of a polymer gasket enclosed in a conductive mesh and in a relaxed state. 
       FIG. 5  is a section view of the conductive edge of the frame. 
       FIG. 6  is a section view of the conductive edge of the door showing a flange for compressing a conductive gasket against the frame. 
       FIG. 7  is a section view of the door and frame showing an alternative embodiment of the invention in an open position. 
       FIG. 7A  is a section view of the door and frame showing an alternative embodiment of the invention in a closed position. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides for inventive concepts capable of being embodied in a variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific manners in which to make and use the invention and are not to be interpreted as limiting the scope of the instant invention. 
   The claims and the specification describe the invention presented and the terms that are employed in the claims draw their meaning from the use of such terms in the specification. The same terms employed in the prior art may be broader in meaning than specifically employed herein. Whenever there is a question between the broader definition of such terms used in the prior art and the more specific use of the terms herein, the more specific meaning is meant. 
   While the invention has been described with a certain degree of particularity, it is clean that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is to be limited only by the scope of the attached claim or claims, including the full range of equivalency to which each element thereof is entitled. 
   Turning now to the drawings a door  10  is arranged to swing about hinges (not shown) located at the right of the portion of the door illustrated in FIG.  1 . This door cooperates with a frame  11  which may be a portion of the wall of a radiation-proof enclosure to which the door is mounted. As shown in  FIGS. 1 and 2  both door  10  and frame or wall  11  may be composed of wood laminations  12  and  13  respectively and these are sheathed on their opposite sides or faces by metallic sheets  14 ,  16  and  15 ,  17 . A conductive joint member  26  is mounted on the edge of door frame  11  and a cooperative conductive joint member  40  is mounted on the corresponding edge of door  10 . 
   Joint member  26  has a pair of flanges  22 ,  24  which are mounted in fixed relation to door frame  11  and has a vertical channel  30  formed by side walls  33  and  35  which project forwardly from the bottom of the channel or back wall  28 . A mouth or opening  31  of channel  30  facing the outside of the enclosure is disposed to the left of door  10  as shown in FIG.  1 . 
   A pair of arch formed resilient contact members  60 ,  61  are disposed in the channel in a manner forcing compression of said members to displace towards sidewalls  33  and  35  and rear wall  28 . Said displacement providing for insertion ease beyond that afforded by the &#39;337 patent which failed to allow for rearward compression (directional) response and counter productively enforced a directional response to compression towards channel opening  31 . Each contact is made from beryllium copper and comprises an elongated comb-like strip of metal of generally uniform cross-section including opposite generally parallel edges  63 ,  67 , one edge  63  rearwardly engaging sidewall  35  and the other edge  67  engaging sidewall  35  adjacent opening  31  of the channel, a flat planar portion  62  extending from edge  67 , a bowed rearward section  64 , a bowed central section  66 , and a bowed forward section  68  adjacent the edge  67 . A plurality of slots  70  extend inwardly from edge  67  to their terminus  71  in planar portion  62  defining a plurality of laterally separated fingers  72 . 
   Cooperating joint member  40  of the radiation resistant joint is secured to door  10  and includes flanges,  42 ,  44 ,  46  and a rigid blade member  48  extending perpendicularly from flange  46 . A plurality of arched contact plates represented as literally separated fingers are attached to flange  44  by planar section  86 . The blade member  48  is adapted to enter into the channel  30  and has slightly tapered leading edges  48   a ,  48   b  to enhance entry into the channel when engaging the opposed resilient contact members  60 ,  61  and an end  49  for engaging a deformable conductive gasket  50  abutting the back wall  28  of the channel  30 . 
   The flange  46  has an inner face  45  adapted to confront the frame  11  and extend laterally beyond (i.e. overlap) the outer peripheral edges of the doorway in a covering relation about the channel opening  31 . 
   Further shown in association with the drawings, most particularly  FIGS. 1 ,  2 , and  3 A is a contact member  80  having a forward edge  81  and rear edge  82 . Said contact member  80  further comprises a bowed rear section  83 , bowed central section  84  and a bowed forward section  85 . A planar portion  86  and a plurality of slots  87  which extend inwardly from rear edge  82  to then terminus  89  defining a plurality of laterally separated fingers  90 . 
   The deformable conductive gasket  50  mounted in the channel  30  against the back wall  28  functions to reduce acoustic levels and provide electrical contact between the contact members  60   61 , the back wall  28  and the blade  48 . Gasket  50  is elongated, generally cylindrical and comprised of a deformable polymer  54  enclosed by a conductive metal mesh  52  which preferably comprises coated copper clad steel, tin plated phosphor bronze, silver plated brass, MONEL (an alloy) or aluminum. 
   The side walls  33 ,  35  and back wall  28  of the channel  30  describe a lengthwise extending truncated edge shaped cross-section including chamber  37  adjacent to the back wall  28 . Each side wall includes an end wall  34  defining a shoulder  38  and first and second side wall portions  32   36 , the first side wall portion  32  defining part of the chamber  37  and extending outwardly from the back wall  28  of the channel  30  and to the wall  34 , and the second side wall portion  36  extending inwardly from the mouth or opening  31  leading into the channel  30  and to the shoulder  38 . The end walls  34  face the back wall and extend between the first and second side wall portions whereby to cause a the second side wall portions  36  to be laterally offset from and superposing the first side wall portions  32 . The end walls  34 , the first side wall portions  32 , and the back wall  28  define the elongated chamber  37 . To advantageously cooperate with the contact members  60 ,  61 , the side walls are inclined away from one another at an acute angle relative to a perpendicular drawn from the back wall  28 . As shown, the two wide walls  33 ,  35  are symmetrically disposed to the perpendicular and the first side wall portions  32  define a double included angle “2A” of between 10 and 50 degrees. In one construction an acute angle “A” of about 16 degrees was found suitable. It is to be understood that each second side wall portion  36  could be the same as or at a different angle than its first side wall portion  32 . 
   The contact members  60 ,  61  are positioned in the channel  30  such that the rearward edge  63  of each contact conductively engages the gasket  50  and each contact conductively engages its respective side wall  33 ,  35  at three points, namely, the bowed rearward section  64  engages the first side wall portion  32 , and the bowed forward section  68  engages the second side wall portion  36  and the shoulder or knife edge  38 . Once inserted in the channel  30  the contact members  60 ,  61  are held in place by the ridge formed by  34 ,  38  whereupon the gasket  50  is inserted to engage end wall  28  and bowed rear sections  64  of contact members  60 ,  61 . The shoulder  38  on each side wall defines a fulcrum such that when the blade  48  engages the bowed central section  66 , the bowed forward and rearward section  64 ,  68  of each plate is biased against its side wall portion  32 ,  36 . The knife edge  38  provides a high unit loading contact against the plates  60 ,  61  at  65  to ensure that electrical conductivity is not compromised by oxides or grit that may form on the metal. 
   The planar portions  62 , while shown at an acute angle to a perpendicular drawn from back wall  28 , are generally pressed against their inner second side wall portions  34 ,  35 . Driving entry and positioning of the blade tip  49  against gasket  50  ensures that the planar portions  62  engage the side wall portions  32  and the edge  63  is driven against the wall  28 . Advantageously four points of contact are achieved between each plate and the channel. Due to the slope of the second side wall portion  36  adjacent the channel opening  31  being complementary to the bowed forward section  68  of the contacts, frictional forces resisting opening or closing of the door are reduced without sacrifice in desired wiping of the side wall thereby assuring that a good electrical path is established between the joints. 
   In a readily envisioned alternative embodiment,  FIGS. 7 and 7A  illustrate the door section  10  and frame section  11  illustrated absent the bowed contact member  80  which has been discussed and disclosed in detail in association with  FIGS. 1 through 6 . 
   It will of course be understood that various changes may be made in form, details, arrangement and proportions of the apparatus without departing from the scope of the invention, which generally stated consists of an apparatus capable of carrying out the objects above set forth, in the parts and combination of parts as disclosed and defined in the appended claims.