Abstract:
A lock system for releasably locking a first component, pivotally coupled along a pivot axis to a second component, in a plurality of positions fixed relative to the second component. The system includes a first engaging mechanism fixed to the first component and aligned with the pivot axis such that it rotates in a rotation plane substantially perpendicular to the pivot axis when the first component is pivoted relative to the second component. The system also includes a second engaging mechanism pivotally mounted to the second component and movable between a first engaged position in which the second engaging mechanism fixedly engages with the first engaging mechanism, preventing the first component from pivoting relative to the second component, and a second disengaged position removed from the first engaging mechanism wherein the first component is free to pivot relative to the second component.

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of folding support legs. 
     BACKGROUND OF THE INVENTION 
     Some prior art folding table legs comprise an articulated cross-support mechanism which spans between the leg and the underside of the tabletop. Often, the cross-support mechanism has a hinge in its middle which permits it to fold back upon itself when the leg is collapsed against the tabletop, but which is designed to prevent the cross-support from pivoting much past 180° at its full extension, when the leg is erected. These cross-supports maintain their spanning strength through the use of gravity or some form of friction lock which works to keep the cross-support extended. Such support legs tend to be flimsy and easily collapsed by accident once erected. 
     Alternatively, some cross-support mechanisms are locked in their extended position through the use of a locking pin. While such mechanisms tend to be more secure in maintaining the leg in its erect position, the locking pins are frequently difficult to use. If the pin is lost, the table leg is rendered unusable until a replacement is found. Frequently, the locking pins are attached to the table through the use of a lengthy chain, which can become tangled when the table leg is collapsed. 
     Other devices have been developed to improve the stability of the collapsible legs, and to lock them in the erect position. However, such designs tend to be complex, both from the manufacturing standpoint, and from the user&#39;s perspective. 
     Additionally, many collapsible table leg designs fail to provide a retention device for maintaining the table leg in its collapsed position. In order to keep the legs from extending and becoming obstructive, it is typically necessary to ensure that the table is transported and stored in an upside-down position. 
     Accordingly, it has been recognized that there is a need for a collapsible table support mechanism, which is sturdy, simple to use, and which is capable of locking the support in both its collapsed and extended positions. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards a collapsible support mechanism, which has common, but by no means exclusive application to folding table legs. 
     The lock system of the present invention is for releasably locking a first component, pivotally coupled along a pivot axis to a second component, in a plurality of positions fixed relative to the second component. The system has a first engaging mechanism fixed to the first component and aligned with the pivot axis such that it rotates in a rotation plane substantially perpendicular to the pivot axis when the first component is pivoted relative to the second component. The system also has a second engaging mechanism pivotally mounted to the second component and movable between an engaged position in which the second engaging mechanism fixedly engages with the first engaging mechanism, preventing the first component from pivoting relative to the second component, and a disengaged position removed from the first engaging mechanism wherein the first component is free to pivot relative to the second component. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example only, with reference to the following drawings, in which like reference numerals refer to like parts and in which: 
     FIG. 1 is a bottom plan view of a locking mechanism manufactured in accordance with the subject invention, in which the support is locked in a collapsed position; 
     FIG. 1A is a side sectional view of a hinge knuckle of the locking mechanism in FIG. 1; 
     FIG. 1B is an overhead view of the engaging bar and spring in FIG. 1, with portions of the hinge mechanism removed; 
     FIG. 2 is a side, close-up view of the locking mechanism of FIG. 1, in which the support is locked in a collapsed position; 
     FIG. 3 is a bottom perspective, close-up view of the locking mechanism of FIG. 1, in which the lock mechanism is disengaged, and the support is in the collapsed position of FIG. 2; 
     FIG. 4 is a side, close-up view of the locking mechanism of FIG. 1, in which the support is locked in an erect position; 
     FIG. 5 is a bottom perspective, close-up view of the locking mechanism of FIG. 1, in which the lock mechanism is disengaged, and the support has been moved between the collapsed position of FIG. 2 and the erect position of FIG. 4; 
     FIG. 6 is a side, close-up view of an alternate locking mechanism of the subject invention, in which the plate of the first engaging mechanism is substantially pentagonal in shape; 
     FIG. 7 is a side, close-up view of an alternate locking mechanism of the subject invention, in which the plate of the first engaging mechanism is substantially hexagonal in shape; 
     FIG. 8A is a side view of a table comprising collapsible legs utilizing the locking mechanism of FIG. 1, in which the legs are locked in an erect position; 
     FIG. 8B is a bottom perspective view of the table of FIG. 8A, in which the legs are locked in a collapsed position; 
     FIG. 9 is a side view of a collapsible table wing comprising a locking mechanisms manufactured in accordance with the subject invention, in which the table wing is locked in an extended, in use position; and 
     FIG. 10 is a side view of a drafting table comprising collapsible legs utilizing the locking mechanism of FIG. 7, in which the tabletop is locked in a position between the horizontal and vertical. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring simultaneously to FIGS. 1 and 2, illustrated therein is a lock system, shown generally at  10  and made in accordance with a preferred embodiment of the subject invention. Lock system  10  comprises a first component  12 , pivotally coupled to a second component  14  through the use of a hinge mechanism  16 , and a locking mechanism  17 . The first component  12  is shown locked in its collapsed position. 
     Typically, the first component  12  is a support member, such as a table leg, and correspondingly, typically the second component  14  is a tabletop. Preferably, the first component  12  comprises a main stem  18  (eg. a tube) having a base stabilizing member  20 , which provides lateral stability when in contact with the floor when the leg is in its erect position. Base member  20  may also comprise adjustable feet  22 , which may be screwed in and out for height adjustment with respect to the base member  20 , for optimal contact with the floor, as will be understood by one skilled in the art. In the example shown, main stem  18  is of tubular metal construction, typically cylindrical in shape, through which the base member  20 , also typically of tubular metal construction, has been passed. 
     The hinge mechanism  16  comprises a support plate  24  which is mounted to the underside of the tabletop  14 , typically through the use of mounting screws  26 . Hinge knuckles  28  are typically welded to the support plate  24 , and comprise a U-shaped portion  30 , within which tube segment  32  has been mounted (FIG.  1 A). Tube segment  32  is sized to slidably receive hinge pin  34  (which also may be tubular). Hinge pin  34  is fixedly mounted through the main stem  18 , typically through welding the two components together. Hinge pin  34  is aligned to pivot about a pivot axis  36 , shown by the dotted line. The periphery of hinge pin  34  is spaced by distance D (FIG. 1A) from the adjacent surface of plate  24 , for a purpose which will become apparent. 
     The locking mechanism  17  comprises a first engaging mechanism  38 , typically a substantially square metal locking plate, which is fixed (eg. by welding) to one end of the hinge pin  34 . The locking plate  38  is centrally aligned to substantially rotate about the pivot axis  36 , in a rotation plane  40 , represented by a dotted line, which is substantially perpendicular to the pivot axis  36  and to the paper on which FIG. 1 is printed. The locking mechanism is shown in FIGS. 1 and 2 in its engaged or locked position. 
     The locking mechanism  17  also comprises a second engaging mechanism  42 , typically a substantially rectangular bar, which is pivotally mounted to the support plate  24  through the use of a screw  44  extending through a hole in the bar  42 . The hole in the bar  42  is sized to permit the bar  42  to freely pivot about the screw  44 , while pivotally fixing the bar  42  to the support plate  24 . Preferably, the locking mechanism  17  also includes a U-shaped biasing spring element  46 , mounted to the nearest hinge knuckle  28 . A reinforcing pin  47  (see also FIG. 1B) may also be provided, mounted to the support plate  24  and positioned on the interior of the spring  46 , with the spring  46  passing between the pin  47  and the nearest knuckle  28  and then bent at  49  against the inside of U-shaped member  30 . The spring  46  is sized to fit around the pivoting end of the bar  42 , and has a free, flexing arm  48 , which maintains biasing force against the bar, urging it towards the nearest knuckle  28 . 
     The bar  42  is positioned in the gap  43  (FIG. 2) between the locking plate  38  and the support plate  24 . Gap  43  is part of the distance D shown in FIG.  1 A. In this engaged position, the bar  42  prevents the locking plate  38  from rotating to any substantial degree, and thereby locks the table leg  12  in its collapsed position. 
     Referring now to FIG. 3, the table leg  12  is shown in the collapsed position of FIG. 2. A user has exerted and maintained counter force against the biasing force of the flexing arm  48  of the spring  46  and flexed it outward, by pivoting the free end of the bar  42  outward in the direction of the arrow, away from the nearest hinge knuckle  28 , and out of the gap  43 . As a result, the locking mechanism  17  is disengaged or unlocked, and the table leg  12  is freed to rotate towards a vertical, erect position. 
     In FIG. 4, the table leg  12  has been rotated approximately 90° to its erect position. As a result, the locking plate  38  has correspondingly been rotated approximately 90°. In the same fashion as was illustrated in FIG. 2, the bar  42  is positioned between the locking plate  38  and the support plate  24 , and in this engaged position, the bar  42  again prevents the locking plate  38  from rotating to any substantial degree. As a result, the table leg  12  is locked in its erect position. 
     Referring now to FIG. 5, the table leg  12  is shown part way between the collapsed position of FIGS. 2 and 3 and the erect position of FIG.  4 . When in the disengaged position of FIG. 5, the table leg  12  has been rotated toward the vertical. In this position, the bottom corner of the locking plate  38  has been rotated and projects into the space which had previously formed the gap  43  in FIG.  2 . As a result, when the bar  42  has been released by the user, the spring  46  urges the bar  42  into contact with the outer surface of the locking plate  38 . As shown in FIG. 5, the lock system  10  may also include a peg  50  for preventing over extension of the spring  46  when the bar  42  is flexed outward by the user. 
     Once the table leg  12  has been rotated completely into the erect position of FIG. 4, a new gap  43 ′ is formed between the bottom side of the locking plate  38  and the support plate  24 , and the spring  46  urges the bar  42  to snap into the newly formed gap  43 ′, thereby preventing further rotation of the table leg  12 . 
     Reference is next made to FIG. 6, which shows an alternate locking mechanism shown generally as  100 . As indicated through the use of similar reference numbers used in FIGS. 1 to  5 , the various components of the alternate mechanism  100  are largely identical to those of the lock system  10 . However, the locking plate  38  has been replaced with metal plate  110  which is substantially pentagonal in shape. As shown in dotted outline, this configuration permits the first component  12  to be locked into three different positions with respect to the second component  14 , each varying by approximately 72° from the next immediate position. 
     Referring now to FIG. 7, illustrated therein is an alternate locking mechanism shown generally as  200 . As indicated through the use of similar reference numbers used in FIGS. 1 to  5 , the various components of the alternate mechanism  200  are largely identical to those of the lock system  10 . However, the locking plate  38  has been replaced with metal plate  210  which is substantially hexagonal in shape. As shown in dotted outline, this configuration permits the first component  12  to be locked into three different positions with respect to the second component  14 , each varying by approximately 60° from the previous position. 
     While the collapsed position of the first component  12  is illustrated in FIGS. 6 and 7 as being essentially parallel to the second component  14 , it should be understood that for certain uses, it may be preferable for the collapsed position to have the first component  12  at some positive angle with respect to the second component  14 . As will be understood, providing for different angles in this manner involves fixing the locking plate  110  or  210  to the hinge pin  34  (not shown in FIGS.  6  and  7 ), and hence to the first component  12  at a different angle than illustrated. Furthermore, it should be understood that the locking plates  38 ,  110 ,  210  may be replaced with locking plates that comprise more than 6 sides. Additionally, it should be understood the locking plates do not need to be regular polygons. In general, any appropriately sized and shaped locking plate having at least two flat sides at its periphery may be used. Typically, the larger the number of sides on the locking plate, the greater the number of adjustable positions available, with smaller angular increments between consecutive positions. 
     Referring now to FIG. 8A, illustrated therein is a table, referred to generally as  300  comprising a pair of collapsible legs  310 ,  312  each utilizing the locking mechanism of the subject invention. The legs  310 ,  312  are shown locked in an erect position. In FIG. 8B, the table  300  is shown with the legs  310 ,  312  in the collapsed position. 
     Referring now to FIG. 9, illustrated therein is a locking system, referred to generally as  400 , in which a table wing  410  is mounted to the edge of a tabletop  412  utilizing a mounting mechanism  414  which comprises components substantially similar to the hinge mechanism  16  and the locking mechanism  17  illustrated in FIGS. 1 and 2. Instead of the table leg  12  of FIGS. 1 and 2, the first component comprises an extension support  416  which is mounted to the table wing  410  by a U-shaped mounting bracket  418  which is welded to both the extension support  416  and a mounting plate  420  which, in turn, is screwed or bolted to the underside of the table wing  410 . When not in use, the table wing  410  can be lowered approximately 90° and locked in a vertical position beneath the tabletop  412 , or if the underside of the tabletop is free from obstruction, may be swung approximately 180° and locked in a position beneath and essentially parallel to the tabletop  412 . As will be understood, the table support for the tabletop  412  may comprise fixed table legs, collapsible table legs (such as the table leg  12  of FIGS.  1  and  2 ), or the tabletop may simply be mounted to and extend from a wall. 
     Referring now to FIG. 10 is the support mounting system  200  of FIG. 7, used on a drafting table, referred to generally as  500 . For stability purposes, the table  500  utilizes two, laterally spaced mounting systems  200 , each comprising a support leg  510  fixedly, pivotally mounted to the underside of the drafting tabletop  512 . As will be understood, the tabletop  512  may be locked in several different positions with respect to the support legs  510 , depending on the user&#39;s preferences. It should also be understood that the locking plate  210  can be replaced with any suitably sized and shaped locking plate, as mentioned previously. 
     While the various locking mechanisms have been illustrated and described in conjunction with tables, and generally in conjunction with table legs, it should be understood that the locking mechanism of the subject invention may be used for many different purposes in which it is desirable to pivotally mount one component to a second component, and be able to releasably lock the first component in position with respect to the second component. 
     Thus, while what is shown and described herein constitute preferred embodiments of the subject invention, it should be understood that various changes can be made without departing from the subject invention, the scope of which is defined in the appended claims.