Patent Publication Number: US-7712422-B2

Title: Folding table

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a table with a folding top and in particular to a table with a folding top that automatically moves into a use position wherein the tabletop cannot be accidentally folded and automatically releases by lifting the top. 
   2. Description of the Prior Art 
   In large, multi-purpose rooms that are utilized at various times as dining rooms, meeting halls, dance areas, training rooms, classrooms and for other varied activities, it is often desirable that multi-purpose furniture be used. Such furniture includes tables, chairs, benches and/or stools or table and seat combinations. Such furniture provides added utility if it folds so that it takes up less space when stored. Examples of folding tables are shown in U.S. Pat. Nos. 2,771,937 to Wilson; 3,075,809 to Wilson; 3,099,480 to Wilson; and 6,254,178 to Bue, all assigned to Sico, Inc., the Assignee of the present invention. 
   Folding tables that are used for quick setup and takedown have added utility if they are easily transported. Therefore, it is desirable to have folding tables mounted on casters or rollers. Moreover, the tables should nest close to one another when folded so that much less floor space is needed when the tables are not in use. 
   In addition to easy transport and less space required for storage, such tables should be easy and safe to operate. Such tables should have a safe, simple and reliable folding mechanism that cannot accidentally allow the table to fold from the use configuration. An issue often encountered with folding furniture is accidental folding. In particular, some folding tables may be subject to accidental folding if a heavy load is placed on an edge of the table. The folding and unfolding should provide sufficient resistance so the tabletop does not fold too quickly, yet does not offer too much resistance leading to accidentally tipping the table over when the top is urged toward a folded position. 
   It can be seen that a new and improved folding table is needed. Such a table should provide for safe and reliable operation with the tabletop folding between a use position and a storage position. The table should nest closely when configured for storage. Moreover, the table should have a linkage that prevents accidental folding from weight being placed on the tabletop surface in the use position. Such a table should not require a separate latch to actuate or separate latching and unlatching steps. Such a table should also provide for safe and reliable actuation when designer tops over a wide range of weights are supported. The present invention addresses these problems, as well as others associated with folding tables and their operation. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a folding table and in particular to a folding table that automatically prevents accidental folding of the table. The folding table includes a folding tabletop mounted on a linkage to a support frame. The frame generally includes a lower frame member attached to rollers or casters for easy transport of the table. The framework includes vertical members near each end of the table and a longitudinal cross member. A linkage mounts to each vertical frame structure and the tabletop is supported by the linkages and the top of the vertical frame structures. 
   Each linkage includes a member mounted to the underside of the tabletop and defining a slot therein. The slot extends generally horizontally and parallel to the tabletop and includes an extended straight portion. An end portion of the slot angles upward and arcs slightly upward from the straight portion at one end of the slot. The straight portion and the angled portion define a toggle point at their juncture. A follower member mounts at the top of the frame and rides in the slot. At the folded position, the follower moves to the end of the slot opposite the angled arcing portion. In the use position, the follower is in the arcing angled portion at its extremity. The arc and angle of the end portion are configured so that the follower can be moved into the straight portion of the slot only when an edge of the tabletop is lifted. The linkage also includes an arm mounted between the underside of the tabletop and the vertical frame structure. The tabletop may include designer finishes such as granite, marble or other finishes that are heavier than conventional tabletop finishes so that additional support and assistance may be needed for folding. Therefore, gas springs or other assist devices may be attached between the tabletop and the frame to assist and control folding between the use and storage positions. 
   In use, the tabletop is generally vertical for storage. This allows for nesting of tables so that less floor space is needed for storage. To configure the table for use, the tabletop is lifted so that the arm and lift spring are pivoted about their lower ends. The lift spring acts as a damper so that the tabletop does not drop quickly. The follower moves along the slot toward the end angled and arcing portion. When the tabletop is moved to the fully horizontal use position, the follower is at the extreme end of the angled portion. With the follower at this point, if pressure is applied to either edge of the tabletop, the geometry of the angled end portion and slight arc prevents the follower from moving back along to the straight portion of the slot. Slight jarring does not move the follower past the intersection, which acts as a toggle point. To move the tabletop from the horizontal use position to a storage position, the edge of the tabletop opposite the arcing portion is lifted slightly and moved toward the folded storage position. This action moves the slot up so that the follower is moved to the bottom edge of the slot so it can pass into the straight section of the slot. The follower moves around the intersection and toggle point and the weight of the tabletop alone can finish the folding to the storage position. The arm helps to guide the tabletop along its path between the folded position and use position and pivoting about the follower. The gas springs act as a damper so that the folding does not occur too quickly in either direction. 
   It can be appreciated that the geometry of the angled portion is important for proper operation. If the angle is too acute and arc radius too small, the follower does not move and the tabletop may be difficult to actuate. If the angle is too flat and the end portion too short, the follower will travel too easily and accidental folding may occur. It has been found that an angle of 25 degrees has provided superior performance results. However, angles of between 20 and 30 degrees have also been found to provide acceptable performance. 
   These features of novelty and various other advantages that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings that form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an end elevational view of a folding table in a use position according to the principles of the present invention; 
       FIG. 2  is an end elevational view of the folding table shown in  FIG. 1  in a folded position; 
       FIG. 3  is a side elevational view of the folding table shown in  FIG. 1  in the use position; 
       FIG. 4  is a side elevational view of the folding table shown in  FIG. 1  in the folded position; 
       FIG. 5  is a bottom plan view of the table top and a portion of the folding linkage for the folding table shown in  FIG. 1 ; 
       FIG. 6  is a detail view of a portion of the linkage for the folding table shown in  FIG. 1 ; and 
       FIG. 7  is a detail view of a portion of the frame and the slot for the folding table shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the drawings and in particular to  FIGS. 1 and 2 , there is shown a folding table, generally designated  10 . The table  10  includes a folding tabletop  12  that folds from a use position wherein the tabletop  12  is horizontal as shown in  FIGS. 1 and 3 , to a folded storage position wherein the tabletop  12  is substantially vertical, as shown in  FIGS. 2 and 4 . The tabletop  12  typically mounts on a support frame  14  that rolls on casters  16 . The casters  16  provide for easy portability. In a preferred embodiment, the casters  16  are lockable so that the table  10  can be secured at a position for use or storage. The frame  14  includes vertical upright structures  40  at opposite ends of the table. The upright structures  40  mount to an associated arcing lower frame member  42  having the casters  26  mounted thereon. The lower frame member  42  may be removably mounted to the uprights  40  for more compact shipping. Longitudinal frame members  44  extend lengthwise and connect the frame upright structures  40 . It can be appreciated that the frame  14  is configured so that when the tabletop  12  is folded to a use position as shown in  FIGS. 2 and 4 , the lower frame members  42  slide beneath the cross members  44  and the tables  10  may be closely nested for storage with the generally vertical tabletops  12  arranged in parallel close to one another. 
   To facilitate folding, the table  10  includes a pair of linkages  20 , one associated with each vertical frame structure  40 . Each linkage  20  includes a first member  22  mounted to an underside of the tabletop  12 , as shown most clearly in  FIGS. 6 and 7 . A longitudinal slot  24  is formed in element  22 . The slot  24  has a substantially straight main portion, but includes an end portion  26  that extends upward from the main section of the slot  24  in a slightly upward arcing manner. The end portion  26  extends at an angle of approximately 25 degrees in a preferred embodiment. However, it has been found that satisfactory performance has also been achieved when the end portion  26  is at an angle of 20 degrees to 30 degrees from the main portion of the slot  24 . A follower  32  mounts on a bracket  48  at the top of the vertical frame structure  40  and acts as a pivot for the tabletop  12 . The follower  32  rests in the slot  24  and moves from the endmost point of the end portion  26  in the use position to the opposite end of the slot  24  in the storage position while the tabletop  12  pivots. The intersection of the main straight portion of the slot  24  with the end portion  26  forms a toggle point  28  that retains the follower  32  in the end portion. In the use position, the follower  32  is securely positioned at the extreme tip of the end portion  26 . 
   The linkages  20  are configured so that the follower  32  cannot accidentally be moved from the use position due to the geometry of the slot  24 . In order to actuate the linkage  20  and move the tabletop  12  from the use position to the storage position, it is necessary to lift the edge of the tabletop  12  opposite the end portion  26 . The lifting moves the end portion of the slot  26  up and allows the follower  32  to move past the toggle point  28  along the lowered edge of the end portion  26 . The tabletop  12  and the linkages  20  may then fold to the folded storage position as shown in  FIGS. 2 and 4 . It can be appreciated that bumping or sitting on any of the edges of the tabletop  12  does not accidentally fold the tabletop  12 . The geometry of the slot end portion  26  prevents the follower  32  from being jarred or sliding beyond the toggle point  28  and prevents accidental folding. 
   Each of the linkages  20  also includes an arm  30  mounted to the first linkage element  22  at the underside of the tabletop and to an upright member  40 . The arm  30  provides guidance and support to the tabletop  12  during folding while the tabletop  12  pivots and slides on the follower  32 . As the linkage  20  is safe and reliable and prevents accidental folding, a tabletop  12  weighing more than conventional tops may be utilized. A heavier tabletop  12 , having a granite, marble or another designer finish, may weigh more and lead to folding at a faster than desired speed. Therefore, a damper  34 , such as a gas spring or gas springs, may be added to one or both of the linkages  20  to control folding between the storage position and the use position. The use of a tabletop  12  having a heavier designer finish provides an improved appearance that may eliminate the need for tablecloths. This speeds setup and take down and saves laundering costs. During folding, the weight of the tabletop  12  causes the tabletop to pivot and slide on the slot  24 , thereby lowering to the folded position on its own, as shown in  FIG. 2 . A stop  36 , shown in  FIGS. 5 and 6 , is engaged by the arm  30  and prevents the tabletop  12  from folding too far and causing damage or leading to the table  10  inadvertently tipping over. In the embodiment shown, the bushing  36  surrounds the follower  32  and provides a larger diameter and protects the follower  32  from damage. 
   Actuation of the table  10  between the folded and unfolded positions is simple and safe according to the present invention. From the unfolded position as shown in  FIGS. 2 and 4 , the lower edge of the tabletop  12  is simply lifted upward. The lifting and folding motion causes the follower  32  to move along the slot  24  past the toggle point  28 . The lifting and folding motion also moves the arm  30  from a substantially vertical position toward an inclined position extending outward from the frame uprights  40 . The gas spring or springs  34  move toward a horizontal position and retract as the tabletop  12  is folded. The follower  32  moves along the slot  24  and passes into the end portion  26  until reaching the extremity of the end portion  26  of the slot  24 . At this position, the tabletop is horizontal and the table  10  is configured for usage. As pressure applied downward to any of the edges does not fold the table  10 , a weight placed on the tabletop  12  does not pose any accidental folding danger. The tabletop  12  is supported on the frame uprights  40  and held by the arm  30  and the follower  32  engaging the end of the slot. Accidental bumping cannot move the follower  32  sufficiently far along the end portion of the slot  26  to pass the toggle point  28 . 
   To fold the table  10 , the edge of the tabletop  12  opposite the end portion  26  is lifted upward pivoting and sliding on the followers  32 . The top  12  must be lifted and folded until the follower  32  passes the toggle point  28 . This occurs when the tabletop is lifted approximately 4 degrees. The folding motion is assisted by the damper  34  and guidance is also provided by the arm  30 . Once the follower  30  passes the toggle point  28 , the tabletop  12  will fold to the use position under its own weight. The top continues to fold until the arm  30  engages the stop or bushing  36  as shown in  FIGS. 2 and 4 . It can be appreciated that the angle, arc and length of the end portion  26  is important so that the follower  32  cannot be moved inadvertently to the straight portion of the slot  24 . It can be appreciated that the angle of the end portion  26  cannot be too great and offer too much resistance as an operator may accidentally tip the table  10  over while lifting. Conversely, the length of the end portion  26  must not be too short and the angle too flat or the follower  32  may pass too easily past the toggle point  28 . Testing provided an optimal angle of approximately 25 degrees between the end portion  26  and the main portion of the slot  24 . The present invention provides a table and folding linkage that provides for safe, simple and reliable folding of the tabletop between the use and storage positions not possible with prior folding tables. 
   It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.