Abstract:
An adjustable food shield includes a pair of support columns, a pair of rotation and detent mechanisms, a top shelf resting on and attached to the top ends of the support columns, a pair of rotation arms. One of the rotation arms is coupled respectively to each of the rotation and detent mechanisms, such that the rotation arms are rotatable about an axis generally parallel with a lengthwise dimension of the adjustable food shield. The rotation and detent mechanisms provide detents at a number of angular positions of the rotation arms. The adjustable food shield further comprises a shield panel fixed to the rotation arms.

Description:
BACKGROUND OF THE INVENTION 
     Food shields, also sometimes called sneeze guards, are used in a variety of settings. Typically, a clear panel is suspended over a buffet, smorgasbord, salad bar, retail display, or other kind of food display to protect the food from falling debris or other contamination. One or more panels may also be placed between the displayed food and customers, such that the customers must reach under the food shield to have access to the food, and the opportunities for contamination are limited. 
     Various health and safety codes and independent design guidelines may specify the required position of the food shield in relation to the food display. Because food shields are used in many different locations, it is desirable that a food shield be easily adjustable, so that it can be adapted to different spaces and uses. Some prior food shields are described in U.S. Pat. No. 6,588,863 to Yatchak et al., issued Jul. 8, 2003 and titled “Sneeze Guards and Methods for Their Construction”, the entire disclosure of which is hereby incorporated herein by reference for all purposes. While the sneeze guards described in that patent have proven very useful, even more adjustability and configurability are desirable. Other prior food shields are described in U.S. Patent Application Publication No. 2011/0169384 of Padden et al., filed published Jul. 14, 2011 and titled “Food Shield”, and U.S. Pat. No. 8,403,430 to Atkins, issued Mar. 26, 2013 and titled “Adjustable Food Shield”, the disclosures of which are hereby incorporated herein by reference for all purposes. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one aspect an adjustable food shield comprises a pair of support columns, one at each end of the adjustable food shield. Each support column has a top end and a bottom end and includes features for affixing the support column to a surface at the bottom end of the support column. Each support column also includes an integral feature near the midpoint between the top and bottom ends for coupling to a rotation and detent mechanism. The adjustable food shield further comprises a pair of rotation and detent mechanisms, one of the rotation and detent mechanisms coupled respectively to the integral feature of each support column. The adjustable food shield further comprises a top shelf resting on and attached to the top ends of the support columns, the top shelf having a front edge and a back edge. The adjustable food shield further comprises a pair of rotation arms. One of the rotation arms is coupled respectively to each of the rotation and detent mechanisms, such that the rotation arms are rotatable about an axis generally parallel with a lengthwise dimension of the adjustable food shield. The rotation and detent mechanisms provide detents at a number of angular positions of the rotation arms. The adjustable food shield further comprises a shield panel fixed to the rotation arms. In some embodiments, the top shelf includes a main portion made of glass and a downwardly-angled lip made of glass, the main portion and the downwardly-angled lip being bonded together at their common edge. In some embodiments, the rotation and detent mechanisms limit the angular travel of the rotation arms and shield panel, and the shield panel can reach at least a horizontal orientation under the top shelf, and a vertical orientation near and below the front edge of the top shelf. In some embodiments, the detent mechanisms provide detents for the horizontal orientation of the shield panel, the vertical orientation of the shield panel, and at least one intermediate orientation of the shield panel between the horizontal and vertical orientations. In some embodiments, the adjustable food shield further comprises at least one retractable locking pin configured to lock the rotation and detent mechanisms at each of the detent positions. In some embodiments, each rotation and detent mechanism comprises: a detent body of a shape and size to mount to the integral feature of the respective support column, the detent body defining a cavity and the detent body including a travel limiter protruding into the cavity, the travel limiter having two fixed travel limiting faces; a detent plate of a shape and size to nest and rotate within the cavity of the detent body, the detent plate having two limiting surfaces between which the travel limiter of the detent body is disposed, such that one of the two limiting surfaces engages a respective one of the fixed travel limiting faces of the detent body at each extreme of angular rotation of the arms, and the detent plate includes features for engaging a respective one of the arms such that the arm rotates with the detent plate; and one or more spring loaded ball plungers mounted in the detent body, each ball plunger positioned to engage a recess in the detent plate at each of the detent positions in the rotation of the arms. 
     According to another aspect, a rotation and detent mechanism comprises a body defining a cavity, the body having a travel limiter protruding into the cavity, and the travel limiter having two fixed faces. The rotation and detent mechanism further comprises a detent plate of a shape and size to nest and rotate within the cavity of the body. The detent plate has two limiting surfaces between which the travel limiter of the body is disposed. One of the two limiting surfaces engages a respective one of the fixed travel limiting faces of the body at each extreme of angular rotation of the detent plate, and the detent plate includes a plurality of recesses on a face perpendicular to the axis of the rotation of the detent plate. The rotation and detent mechanism further comprises one or more spring loaded ball plungers mounted in the body and aligned with the axis of rotation of the detent plate. Each ball plunger is positioned to engage a recess in the detent plate at each of certain angular positions of the detent plate within the body, such that the certain angular positions are detent positions. The rotation and detent mechanism further comprises an axle on which the detent plate rotates, the axle defining an axis of rotation of the detent plate. In some embodiments, the rotation and detent mechanism further comprises a shoulder screw that functions as the axle and constrains the detent plate axially with respect to the body, and a pair of thrust washers, one on each side of the detent plate. In some embodiments, the detent plate defines a hole for receiving a locking pin, the body defines a plurality of locking holes, and the hole in the detent plate aligns with one of the locking holes in the body at each of the detent positions of the detent plate, permitting insertion of a locking pin through the detent plate and into the body. In some embodiments, the detent plate further includes a geometric protrusion from a side opposite the body, for attachment of other elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an adjustable food shield in accordance with embodiments of the invention. 
         FIG. 2  illustrates the adjustable food shield of  FIG. 1  in an alternate configuration. 
         FIG. 3  illustrates the adjustable food shield of  FIG. 1  in another alternate configuration. 
         FIG. 4  illustrates the adjustable food shield of  FIG. 1  in another alternate configuration. 
         FIGS. 5A and 5B  provide exploded perspective views from two different angles of a rotation and detent mechanism, in accordance with embodiments of the invention. 
         FIG. 6  illustrates a more detailed view of a detent body, in accordance with embodiments of the invention. 
         FIGS. 7A and 7B  show more detailed views of a detent plate, in accordance with embodiments of the invention. 
         FIG. 8  illustrates the detent body of  FIG. 6  and the detent plate of  FIGS. 7A and 7B  nested together as when assembled into the food shield of  FIG. 1 , in accordance with embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an adjustable food shield  100  in accordance with embodiments of the invention. Example food shield  100  is mountable to a surface  101 , which may be for example a surface of a buffet table, serving counter, or other installation where protection of items is desired. In the case of a food service installation, it may also be desired that the food items be attractively displayed and be visible, and in the case of a self-service buffet, customer access to the food items is necessary. 
     Food shield  100  includes two support columns  102   a  and  102   b , one at each end of food shield  100 . Preferably, support columns  102   a  and  102   b  include features for attaching them securely to surface  100 . For example, support columns  102   a  and  102   b  may include threaded holes (not visible) in their bottom faces, to receive mounting bolts from below surface  101 . Other mounting methods are also possible. Each of support columns  102   a  and  102   b  includes a bottom end at surface  101 , and a top end opposite the bottom end. Support columns  102   a  and  102   b  may be made from any suitable material and formed in any suitable way, but may conveniently be die case from zinc or aluminum, and may be plated, painted, or otherwise decoratively finished. 
     A top shelf  103  rests on and is attached to the top ends of support columns  102   a  and  102   b . Top shelf  103  may (but need not) be made of glass or another transparent material, and may be attached to support columns  102   a  and  102   b  by any convenient technique, for example by bolts through holes in top shelf  103  and threaded into support columns  102   a  and  102   b . Such bolts may have decorative heads, or may be covered with decorative caps  104 . Other fastening techniques may be used as well. 
     Top shelf  103  may function as a shelf, for example to display items placed on top of shelf  103 , and also functions as a shield to protect the area below top shelf  103  from contamination that my fall from above. In some embodiments, top shelf  103  includes a horizontal main portion  105  and a downwardly-angled lip  106  joined to the front edge of main portion  105  shared with lip  106 . The two portions may be made of glass, and may be bonded together, for example using an adhesive cured by ultraviolet light. Lip  106  may provide additional protection of the displayed items, and may assist in meeting food shield design guidelines as is explained in more detail below. Although other dimensions may be used, top shelf  103  may be disposed about 20 to 21 inches above surface  101 . 
     Food shield  100  further includes a pair of rotation arms  107   a  and  107   b , and a shield panel  108  fixed to the rotation arms  107   a  and  107   b . Rotation arms  107   a  and  107   b  and shield panel  108  are rotatable as indicated in  FIG. 1 , about an axis defined by a pair of rotation and detent mechanisms (not visible in  FIG. 1  but described in detail below). Rotation arms  107   a  and  107   b  may be made of any suitable material and may be made in any suitable way, but may conveniently be made using the same materials and finishes as support columns  102   a  and  102   b . Shield panel  108  may be affixed to rotation arms  107   a  and  107   b  by any suitable technique, for example by bolts  109  through holes in shield panel  108  and threaded into rotation arms  107   a  and  107   b . Bolts  109  may have decorative heads or may be covered by decorative caps, if desired. 
     Shield panel  108  can preferably reach at least a horizontal orientation under top shelf  103 , as shown in  FIG. 2 , and a vertical orientation near and below the bottom edge of lip  106 , as shown in  FIG. 3 . Preferably, the gap  301  remaining between lip  106  and shield panel  108  when shield panel  108  is in the vertical orientation is 0.75 inches or less across, in accordance with certain food shield design guidelines. Shield panel  108  may be made of glass or another transparent material when visibility of protected items is desired. 
     In addition to the orientation shown in  FIG. 1 , in which shield panel is at 45 degrees from horizontal or vertical, shield panel  108  can reach other intermediate orientations as well. For example, shield panel  108  may be placed in an intermediate orientation similar to that shown in  FIG. 4 , to allow customer access to buffet items or the like. In accordance with certain guidelines, the distance  401  from surface  101  to the lower edge of shield panel  108  may be about 13 inches. In the example embodiment of  FIG. 4 , this corresponds to placing shield panel  108  at about 22.5 degrees from horizontal, but other angles may be used, but the correct spacing to surface  101  may be achieved using different angles in other embodiments. 
     A pair of rotation and detent mechanisms is provided at the connections of rotation arms  107   a  and  107   b  to support columns  102   a  and  102   b .  FIGS. 5A and 5B  provide exploded perspective views from two different angles of a rotation and detent mechanism  500 , in accordance with embodiments of the invention. 
     As shown in  FIG. 5A , support column  102   b  has an integral pocket  501  for coupling to rotation and detent mechanism  500 . For example, pocket  501  may be formed during die casting of support column  102   b . A detent body  502  attaches to support column  102   b  via bolts  503 . Detent body  502  defines a cavity  504 , which in this example is generally cylindrical, although this is not a requirement. Protruding into cavity  504  is a travel limiter  505 , which has two fixed travel limiting faces  506 . (Only edges of travel limiting faces  506  are visible in  FIG. 5A .) Detent body  502  may be made of any suitable material and by any suitable process, but may conveniently be made using materials and processes similar to those used to make support column  102   b.    
     One or more spring loaded ball plungers  507  are placed in holes  508  in detent body  502 . As will be appreciated, detent body  502  remains stationary, attached to support column  102   b  and holding ball plungers  507 . 
     A detent plate  509  is of a shape and size to rotate within cavity  504 , on a shoulder screw  510  (best visible in  FIG. 5B ) that acts as an axle about which detent plate  509  rotates, and that defines the axis of rotation of detent plate  509 . Thrust washers  511  may be used to minimize mechanical play between detent plate  509  and other components. Detent plate  509  includes a number of recesses  512  positioned to align with ball plungers  507  when shield panel  108  is in its respective detent positions. In  FIG. 5B , four sets of three recesses  512  are shown, even though example food shield  100  can place shield panel  108  in four different detent positions. Some of recesses  512  can be used by different ball plungers, for example when shield panel  108  is in its vertical and horizontal orientations. 
     Detent plate  509  may be made of any suitable material and by any suitable process, but may conveniently be machined from steel or stainless steel, and may be hardened if desired. 
     Detent plate  509  also includes a geometric protrusion  513  (visible in  FIG. 5A ) of a size to mate with geometric recess  514  (visible in  FIG. 5B ) in rotation arm  107   b . The nesting of geometric protrusion  513  and recess  514  helps prevent relative rotation between rotation arm  107   b  and detent plate  509 . A setscrew (not shown) may also be inserted through hole  515  to bear on a surface of geometric protrusion  513 , to hold rotation arm  107   b  to detent plate  509 . 
     When rotation arm  107   b  and detent plate  509  reach one of the detent positions, ball plungers  507  fall into recesses  512 , to hold rotation arm  107   b  and detent plate  509  in the detent position. The detent action of the ball plungers can be overcome by moderate force on rotation arms  107   a  and  107   b  or shield panel  108 . A locking pin  516  may also be used, passing through detent plate  509  via hole  519  and engaging one of locking holes  517  in detent body  502 , to lock the system in the detent position. 
     Detent plate  509  also includes two travel limiting surfaces  518  that respectively engage travel limiting faces  506  of detent body  502  at the extremes of travel of shield plate  108 . 
       FIG. 6  illustrates a more detailed view of example detent body  502 . In particular, travel limiting faces  506  are visible in  FIG. 6 .  FIGS. 7A and 7B  show more detailed views of example detent plate  509 . It will be appreciated that in some embodiments, mirror image left- and right-handed versions of some parts may be provided, possibly including detent plate  509 , support columns  102   a  and  102   b , and rotation arms  107   a  and  107   b . In other embodiments, identical versions of some or all of these parts may be usable at both ends of food shield  100 . 
       FIG. 8  illustrates detent body  502  and detent plate nested together as when assembled into food shield  100 . In the configuration of  FIG. 8 , detent plate  509  is at one extreme of its travel, and has contacted travel limiter  505  at interface  801 . 
     The invention has now been described in detail for the purposes of clarity and understanding. However, those skilled in the art will appreciate that certain changes and modifications may be practiced within the scope of the appended claims.