Abstract:
A fastener for releasably securing a first substrate to an apertured second substrate includes a base member and a locking member mounted for rotation relative to the base member. The locking member is rotatable between an insertion position for insertion of the base member and locking member through the aperture formed in the second substrate and a locking position for releasably securing the first and second substrates together. A resilient member is provided to bias the locking member toward the base member when the resilient member is compressed. The locking member includes at least one protrusion and the base member includes at least one detent. The detent and protrusion are configured to releasably engage each other in the insertion position of the locking member and disengage from each other upon rotation of the locking member toward the locking position.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to fasteners and, more particularly, to a fastener for releasably securing a first substrate to an apertured second substrate through a ninety degree or quarter turn rotation of the fastener.  
       BACKGROUND OF THE INVENTION  
       [0002]     Medical examination tables are known to have a patient supporting surface comprising a seat section and an adjustable back section. The back section is movable between a horizontal position and an inclined position so that a patient is supported in an upright position during certain medical examination procedures.  
         [0003]     Typically, the back and seat sections are cushioned and covered with upholstery to provide a comfortable and aesthetically pleasing support surface for the patient. To that end, medical examination tables are typically offered with upholstery of different colors and textures which are selected by the medical examination professional to match a decor of the examination area.  
         [0004]     In the past, the seat and back sections have been assembled as an integral part of the medical examination table and were typically secured to the examination table substructure through multiple screws. This type of assembly method has required manufacturers of medical examination tables to inventory a wide range of assembled examination tables with different upholstery combinations in hopes of having the proper combination to satisfy a purchaser&#39;s particular upholstery request. This approach of securing the back and seat sections to the medical examination table increases the manufacturer&#39;s inventory costs and requires additional storage space at the manufacturing facility to store the wide variety of assembled examination tables.  
         [0005]     Alternatively, the back and seat sections have been secured to the medical examination table through Velcro® straps or snaps provided on the back and seat sections. However, these types of fastening structures are oftentimes difficult to clean and are susceptible to damage over an extended period of use. When the Velcro® straps or snaps become damaged, the back and seat sections are not firmly secured to the medical examination table and the entire back or seat section must be removed and replaced.  
         [0006]     Accordingly, there is a need for a fastener to removably secure a back or seat section of a medical examination table to a substructure of the examination table which overcomes these and other drawbacks of the prior art.  
       SUMMARY OF THE INVENTION  
       [0007]     The present invention overcomes the foregoing and other shortcomings and drawbacks of fastening arrangements heretofore known for securing a back or seat section of a medical examination table to a substructure of the examination table. While the invention will be described in connection with certain embodiments, it will be understood that the invention is not limited to these embodiments. On the contrary, the invention includes all alternatives, modifications and equivalents as may be included within the spirit and scope of the present invention.  
         [0008]     In accordance with the principles of the present invention, a fastener is provided for removably securing a back section or seat section of a medical examination table to a substructure of the examination table. The fastener is designed to be rotated by hand, i.e., without the use of tools, to secure the back and seat sections to the medical examination table.  
         [0009]     According to one aspect of the present invention, the fastener comprises a base member mounted to a rear surface of the back or seat section and a twistable locking member that is mounted for rotation relative to the base member between an insertion position and a locking position. In the insertion position, the base member and the locking member of the fastener are inserted through an aperture formed in the substructure of the medical examination table. The locking member is rotated ninety degrees or a quarter turn by hand to a locking position to secure the back or seat section to the substructure of the examination table.  
         [0010]     According to another aspect of the present invention, the base member is provided with one or more detents and the locking member is provided with one or more protrusions. The protrusions of the locking member and the detents of the base member are configured to releasably engage each other when the locking member is rotated to the insertion position. This facilitates proper orientation of the locking member relative to the base member during insertion of the fasteners through the apertures. The protrusions and the detents disengage from each other when the locking member is rotated toward the locking position.  
         [0011]     According to yet another aspect of the present invention, one or more outwardly projecting bosses having detents formed therein are provided on the substructure of the medical examination table and positioned outwardly of each aperture. When the locking member is rotated ninety degrees or a quarter turn to the locking position, the protrusions of the locking members engage the detents formed in the bosses to thereby lock the back or seat section to the substructure of the medical examination table.  
         [0012]     In accordance with yet another aspect of the present invention, the fastener includes a resilient member that biases the locking member toward the base member when the resilient member is compressed. The resilient member also provides a clamping force to firmly secure the back or seat section to the substructure of the medical examination table when the locking member is rotated to the locking position.  
         [0013]     In this way, the fastener of the present invention permits the back or seat section to be readily installed or removed from the medical examination table without the use of tools. The back or seat section may be shipped directly to the medical examination site and installed on the medical examination table at that location so that prior assembly of the entire medical examination table at the manufacturer&#39;s facility is no longer required. The fastener of the present invention also gives the medical examination professional the ability to easily remove the back or seat section for cleaning or to replace the back or seat section with another of different color or texture for changing of the appearance of the medical examination table.  
         [0014]     The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
         [0016]      FIG. 1  is a perspective view of an exemplary medical examination table incorporating fasteners of the present invention for securing upholstered back and seat sections to a base of the medical examination table;  
         [0017]      FIG. 2  is a perspective view showing installation of an upholstered back section to a back support of the medical examination table shown in  FIG. 1  with the fasteners mounted to the upholstered back section and rotated to an insertion position;  
         [0018]      FIG. 3A  is a partial perspective view showing one of the fasteners rotated to the insertion position and inserted through an aperture formed in the back support of the medical examination table of  FIG. 2 ;  
         [0019]      FIG. 3B  is a view similar to  FIG. 3A  showing the fastener rotated to a locking position to secure the upholstered back section to the back support of the medical examination table;  
         [0020]      FIG. 4A  is a partial cross sectional view showing one of the fasteners rotated to the insertion position and inserted through the aperture formed in the back support of the medical examination table during installation of the upholstered back section to the back support of the medical examination table; and  
         [0021]      FIG. 4B  is a view similar to  FIG. 4A  showing one of the fasteners rotated to the locking position for securing the upholstered back section to the back support of the medical examination table. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]     Referring now to the figures, an exemplary medical examination table  10  ( FIG. 1 ) is shown incorporating fasteners  12  (FIGS.  2 ,  3 A-B and  4 A-B) of the present invention for releasably securing upholstered back and seat sections  14 ,  16  to a stationary base  18  of the examination table  10 . As will be described in greater detail below, each of the fasteners  12  has a portion configured to be twisted or rotated ninety degrees or a quarter turn between an insertion position and a locking position to releasably secure the back and seat sections  14 ,  16  to the base  18 . While the fasteners  12  of the present invention will be described in detail below in connection with releasably securing the back and seat sections  14 ,  16  to the base  18  of the medical examination table  10 , it will be appreciated by those of ordinary skill in the art that the fasteners  12  of the present invention may be readily incorporated into a variety of other structures or used in a variety of other fastening applications and so are not limited for use with a medical examination table which is described herein in detail by way of example only and without limitation.  
         [0023]     As shown in  FIG. 1 , the back and seat sections  14 ,  16  are mounted atop the stationary base  18  to form a patient support  20 . The back section  14  is moveable relative to the seat section  16  and the base  18  between an inclined orientation for supporting a patient in a seated position and a fully reclined orientation for supporting the patient in a generally supine position. In one embodiment, the position of the back rest  14  is controlled through an adjustment mechanism  22  ( FIG. 1 ) that is operatively connected between the base  18  and a back support  24  (FIGS.  2 ,  3 A-B and  4 A-B) upon which the back section  14  is releasably secured. The adjustment mechanism  22  permits the back section  14  to be manually moved to a desired orientation for a medical examination procedure and thereafter locked in place until the back rest  14  is moved again to readjust the patient. Those of ordinary skill in the art will appreciate that other types of adjustment mechanisms are possible as well without departing from the spirit and scope of the present invention.  
         [0024]     In one embodiment, as shown in  FIGS. 2 and 4 A-B, the upholstered back section  14  includes a support panel  26 , made of wood or other generally rigid material, that is releasably secured to the back support  24  through use of the fasteners  12 . A resilient body  28 , such as a foam pad or other compressible material, is carried by the support panel  26  and is covered with a layer of upholstery  30 . The upholstery  30 , which may comprise leather, vinyl, cloth or other material having a variety of different textures and colors, is stapled, glued or otherwise fastened near its marginal edges to the support panel  26  so as to cover the resilient body  28 . In this way, the back section  14  provides an aesthetically appealing and comfortable padded support surface for the patient and is easily washable following an examination procedure. While not shown, it will be appreciated that the seat section  16  has a construction similar to that of the back section  14  and so the description of the back section  14  and its construction generally applies to the seat section  16  as well.  
         [0025]     Referring now to FIGS.  2 ,  3 A-B and  4 A-B, the fasteners  12  will now be described for releasably securing the back section  16  to the back support  24  of the medical examination table  10  in accordance with the principles of the present invention. In one embodiment, the back support  24  may be a stamped metal part that forms part of the table substructure and includes apertures  32  (four shown) in  FIG. 2  formed therein that are configured to receive the fasteners  12  therethrough as will be described in detail below. An outwardly projecting lip  34  is provided around the periphery of each aperture  32  which may be formed in a known manner during the formation of the apertures  32 . In one embodiment, each aperture  32  is generally oblong in shape and includes major and minor axes along the length and width, respectively, of each aperture  32 . Other shapes of the apertures  32  are possible as well without departing from the spirit and scope of the present invention.  
         [0026]     A pair of outwardly projecting and spaced apart bosses  36  (FIGS.  3 A-B and  4 A-B) are provided on a rear surface  38  of the back support  24  and positioned outwardly of each aperture  32 . Each of the pair of bosses  36  is located on opposite sides of a respective aperture  32  with each boss  36  being positioned generally along the minor axis of the respective aperture  32 . In one embodiment, each boss  36  includes a pair of inclined side walls  40  and a pair of inclined end walls  42  that converge toward a top wall  44 . A detent  46  is formed in the top wall  44  of each boss  36  so as to be positioned generally along the minor axis of each respective aperture  32  and outwardly from the rear surface  38  of the back support  24 . While a pair of bosses  36  is shown associated with each aperture  32 , it will be understood that only a single boss  36  may be associated with each aperture  32  in an alternative embodiment of the present invention.  
         [0027]     Each fastener  12  (four shown) includes a base member  48  mounted to the rear surface  38  of the back support  24  and a twistable locking member  50  that is mounted for rotation relative to the base member  48  between an insertion position ( FIGS. 2, 3A  and  4 A) and a locking position ( FIGS. 3B and 4B ). In the insertion position, the base member  48  and the locking member  50  of each fastener  12  are insertable through a respective aperture  32  formed in the back support  24  as shown in  FIGS. 2, 3A  and  4 A. The locking member  50  is rotatable ninety degrees or a quarter turn by hand, i.e., without the use of tools, to a locking position as shown in  FIGS. 3B and 4B  to secure the back section  14  to the back support  24 . The base member  48  and the locking member  50  of the fasteners  12  may be molded components and made of a material suitable for medical applications.  
         [0028]     In one embodiment, each base member  48  is generally oblong in shape and includes major and minor axes along the length and width, respectively, of each fastener  12 . The base member  48  has a bottom wall  52  in contact with the back support  24 , an opposite and generally flat top wall  54 , and a frusto-conical side wall  56  extending between the bottom and top walls  52 ,  54 . The base member  48  is configured to be received in its respective aperture  32  with the frusto-conical sidewall  56  positioned closely adjacent the lip  34  so as to prevent undesirable movement of the back section  14  relative to the back support  24  when the back section  14  is installed on the medical examination table  10 . The close fit of the base members  48  and the apertures  32  facilitate proper location of the back section  14  relative to the back support  24  during installation of the back section  14  as will be described in great detail below. Other shapes of the base member  48  are possible as well with departing from the spirit and scope of the present invention.  
         [0029]     The base member  48  has a pair of spaced apart stepped bores  58  ( FIG. 3B ) formed therein and positioned generally along the major axis of the base member  48  that receive a pair of screws  60  ( FIG. 3B ). The screws  60  extend through the stepped bores  58  and have remote ends that engage the back support  24  to mount the fasteners  12  to the back section  14 . Washers  62  ( FIG. 3B ) are located in the stepped bores  58  beneath the heads of the screws  60 . The base member  48  also includes a central bore  64  extending therethrough that communicates with a central cavity  66  provided in the bottom wall  52  of the base member  48 .  
         [0030]     In one embodiment, the base member  48  includes a pair of spaced apart detents  68  (FIGS.  3 A-B) located in the top wall  54  and positioned along the major axis of the base member  48 . The detents  68  extend inwardly from the top wall  54  and are located adjacent the frusto-conical side wall  56 . While a pair of detents  68  is shown provided in the top wall  54 , it will be understood that only a single detent  68  may be provided in the top wall  54  in an alternative embodiment of the present invention.  
         [0031]     As shown in FIGS.  3 A-B and  4 A-B, the twistable locking member  50  is rotatably supported on the base member  48  through a fastening assembly  70 . The locking member  50  includes a stepped central bore  72  that is axially aligned with the central bore  64  of the base member  48 . In one embodiment, the fastening assembly  70  includes a rivet  74  extending through the stepped central bore  72  of the locking member  50  and the central bore  64  of the base member  48 . Washers  76 ,  78  are located in the central stepped bore  72  of the locking member  50  and in the central cavity  66  of the base member  48 , respectively. The washer  76  is positioned beneath the head of the rivet  74  and the washer  78  is captured in the central cavity  66  of the base member  48  by a radially outwardly extending flange  80  provided at a remote end of the rivet  74 . While a rivet  74  is shown for rotatably mounting the locking member  50  to the base member  48 , it will be appreciated that other fastening structures, such as a nut and bolt for example, are possible as well without departing from the spirit and scope of the present invention.  
         [0032]     In one embodiment, each locking member  50  is generally oblong in shape and includes major and minor axes along the length and width, respectively, of each fastener  12 . The locking member  50  has a generally flat bottom wall  82  positioned adjacent the generally flat top wall  54  of the base member  48 , an opposite and convex top wall  84 , and a frusto-conical side wall  86  extending between the bottom and top walls  82 ,  84 . Protuberances  88  or other gripping structures may be provided on the frusto-conical side wall  86  to assist a user in gripping of the twistable locking member  50 . Other shapes of the locking members  50  are possible as well with departing from the spirit and scope of the present invention.  
         [0033]     In one embodiment, the locking member  50  includes a pair of spaced apart protrusions  90  extending outwardly from the bottom wall  82  and positioned along the major axis of the locking member  50 . The protrusions  90  of the locking member  50  and the detents  68  of the base member  48  are configured to releasably engage each other when the locking member  50  is rotated to the insertion position as shown in  FIGS. 3A and 4A . This facilitates proper orientation of the locking member  50  relative to the base member  48  during insertion of the fasteners  12  through the apertures  32 . The protrusions  90  and the detents  68  disengage from each other when the locking member  50  is rotated to the locking position as shown in  FIGS. 3B and 4B . While a pair of protrusions  90  is shown extending outwardly from the bottom wall  82 , it will be understood that only a single protrusion  90  may be provided on the bottom wall  82  in an alternative embodiment of the present invention.  
         [0034]     Referring to  FIGS. 4A and 4B , a resilient member  92  is located in the stepped central bore  72  of the locking member  50  and is interposed between the washer  76  and the locking member  50 . In one embodiment, the resilient member  92  is made of an elastomeric material and comprises a sleeve positioned about the rivet  74 , although other resilient structures, such as a spring for example, and other configurations of the resilient member  92  are possible as well without departing from the spirit and scope of the present invention. The resilient member  92  biases the locking member  50  toward the base member  48  upon compression of the resilient member  92 . The resilient member  92  also provides a clamping force to secure the back section  14  to the back support  24  when the locking member  50  is rotated to the locking position shown in  FIGS. 3B and 4B  as will be described in greater detail below.  
         [0035]     During installation of the back section  14  to the back support  24 , each of the locking members  50  is rotated to the insertion position shown in  FIGS. 2, 3A  and  4 A. In this position, the protrusions  90  of the locking members  50  engage the detents  68  of the base member  48  to maintain the locking members  50  in the insertion position. The back section  14  is then mounted to the back support  24  by inserting the fasteners  12  through the respective apertures  32  formed in the back support  24 .  
         [0036]     To firmly secure the back section  14  to the back support  24 , each of the locking members  50  is then rotated ninety degrees or a quarter turn to the locking position shown in  FIGS. 3B and 4B  so that the protrusions  90  of the locking members  50  engage the detents  46  formed in the top walls  44  of the bosses  36  to thereby lock the back section  14  to the back support  24 . During rotation or twisting of the locking members  50  to the locking position, the opposite ends of the locking member  50  engage the inclined end walls  42  of the bosses  36  in the travel path of the locking member  50  which causes the resilient member  92  to be compressed. In this way, the resilient member  92  biases the locking member  50  toward the base member  48  and also provides a clamping force to firmly lock the back section  14  to the back support  26 .  
         [0037]     When the back sections  14  need to be cleaned, repaired or replaced, the back sections  14  are removed from the back support  26  by rotating the locking members  50  to the insertion position shown in  FIGS. 3A and 3B . This rotation disengages the protrusions  90  of the locking members  50  from the detents  46  of the bosses  36  and engages the protrusions  90  with the detents  68  of the base member  48 . The back section  14  is then removed from the back support  24  by withdrawing the fasteners  12  from the apertures  32 . While not shown, it will be appreciated that the seat section  16  is removably secured to the medical examination table  10  in a similar fashion using the fasteners  12  of the present invention.  
         [0038]     While the present invention has been illustrated by the description of one or more embodiments thereof, and while the embodiments have been described in considerable detail, they are not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of Applicants&#39; general inventive concept.