Abstract:
A folding chair of the type having a frame constructed of pivotally connected scissors like “X”-shaped structure strut members supporting a sling seat, the lower ends of which form two front feet and two rear feet and the upper ends of which form two front seat corners and two rear seat corners of the chair. The folding chair includes a pair of upright telescopic supports mounted between the two front seat corners and the two front feet. The upright telescopic supports extend when the frame is folded and collapse telescopically when the chair is deployed. A pair of uprights may extend up from the rear feet and through the rear seat corners so as to extend above the rear of the sling seat to provide a backrest.

Description:
FIELD OF THE INVENTION 
     This invention relates to folding chairs using an X-frame folding design, and more specifically the addition of a telescopic support, which allow the use of an X-frame folding design to substantially support a person of above average weight, without bending the frame structure under regular and harsh use. 
     BACKGROUND OF THE INVENTION 
     Lightweight, foldable stools and chairs are used in camping and other outdoor uses because they can easily be carried, stored compactly and are quick and easy to setup. 
     Some of the simplest devices for portable seating have been triangular or square seats stools with 3 and 4 legs. These simple designs are light compact, but lack strength and also comfort because they cannot easily have a back support. 
     There are many varieties in prior art, showing a constant trend to improve upon weight, foldability, portability and comfort. One such variety is illustrated in FIG.  1 . 
     Inventor is aware of U.S. Pat. No. 4,184,711 issued to Wakimoto Jan. 22, 1980, a four-legged chair with the legs pivotally-coupled by an external center hinge and two back support uprights each hinged separately to a leg. Wakimoto&#39;s patent offers improved compactness by eliminating the horizontal seat supports. However, the external center hinge and back support tubes would not adequately support the weight of a large person. 
     Inventor is also aware U.S. Pat. No. 4,290,643 issued to Logan Sep. 22, 1981, a folding chair comprising a complicated network of eight rigid members, six tension cables, and a complex fabric cover. Although the closed bundle folds in a substantially parallel arrangement for collapsibility, the complex fabric cover can easily be stressed, especially after the material has been exposed to the sunlight over time. Also, it is not seen as an improvement over prior art in regards to ease of assembly. 
     Inventor is also aware U.S. Pat. No. 4,595,232 to Glenn et al. Jun. 17, 1986 which shows a four-legged chair with legs put together as two front-to-back X-shaped frames, two side-to-side horizontal seat supports connecting the X-frames, and two posts extending upright from leg sockets to hold a fabric backrest. A “spacer bar” reinforces the posts above the backrest to eliminate the flex of Wakimoto&#39;s art but adds a hard surface causing user discomfort. However, this design does not improve the collapsibility or lightweight features of existing art. Also, the frame design would not be stable under a heavy person. 
     Inventor is also aware U.S. Pat. No. 4,807,930 to Helfrich Feb. 28, 1989, which shows a four-legged chair with legs, put together using four X-shaped frames, supporting a fabric seat and a fabric backrest, but would be limited in its ability to handle the weight of a large person or the abruptness of a person dropping or plopping down onto the chair. 
     Inventor is also aware U.S. Pat. No. 5,718,473 issued to Lynch Feb. 17, 1998, which is lightweight and collapsible chair, but would also be limited in its ability to handle the weight of a large person or the abruptness of a person plopping down onto the chair. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of this invention to provide a folding chair, which collapses to a compact package for carrying. 
     It is another object of this invention to provide a folding chair, which is lightweight and convenient for carrying, yet strong enough to support a person of above average weight, without bending the frame structure under normal use. 
     It is another object of this invention to provide a folding chair, which can be fixedly deployed so that the seat is held taut. 
     It is yet another object of this invention to provide a folding chair, where the seat is held taut and as such can be used as a stool or a small table. 
     It is still another object of this invention to provide a folding chair that is inexpensive to manufacture and consequently cost effective for a wide number of recreational activities. 
     A folding chair of the type having a frame constructed of pivotally connected scissors-like “X”-shaped structure strut members supporting a sling seat, the lower ends of which form two front feet and two rear feet and the upper ends of which form two front seat corners and two rear seat corners of the chair. The folding chair includes a pair of upright telescopic supports attaching at the two front seat corners towards the two front feet, where upright telescopic supports extend when the frame is folded and withdraw into themselves when the chair is deployed, thereby allowing the frame to support greater weight in use without adding bulk to the folded frame for simple storage or transport. The chair quickly deploys by spreading the front feet, thereby causing the rear feet to spread apart and to extend rearwardly from the front feet. There may also be a pair of uprights extending up from the rear feet and extending through the rear seat corners to extend above the rear of the seat to function as upright supports for a chair seat backrest. 
     In summary the folding chair of the present invention includes “X”-shaped collapsible front and rear structures, and “X”-shaped collapsible left and right side structures. 
     The front, rear, left side and right side structures are pivotally mounted to each other at adjoining corners of the “X”-shaped structures so that the front and rear structures are parallel and spaced apart and so that the left and right side structures are parallel and spaced apart, and so that the front, rear, left and right side structures when so mounted to each other define a rectangular parallelepiped symmetric about an axis of symmetry. The rectangular parallelepiped is expandable or collapsible symmetrically about the axis of symmetry by simultaneous corresponding expansion or collapsing of the “X”-shaped structures about pivots in the center of each the “X”-shaped structure and about the pivotable mounting at the adjoining corners. The adjoining corners form the vertices of the rectangular parallelepiped. The improvement of the present invention resides in at least one telescopic member mounted between vertically aligned vertices of the rectangular parallelepiped. The telescopic member is sized so that when it is fully telescopically retracted, that is, an extendible rod is retracted into a sleeve of larger diameter, the rectangular parallelepiped is fully expanded so as to tension a flexible seat suspended between upper vertices of the rectangular parallelepiped, 
     Advantageously, at least one telescopic member is mounted between vertically aligned front vertices of the rectangular parallelepiped. 
     Further advantageously, the at least one telescopic member may be a pair of parallel linearly telescopic members telescopically extendable and retractable between fully extended positions when the rectangular parallelepiped is fully collapsed about the axis of symmetry, and fully retracted positions when the rectangular parallelepiped is fully expanded. 
     The folding chair of the present invention may also be summarized as including: 
     a) a front transverse “X”-shaped structure formed by first and second rigid members pivotally coupled scissor-like together at midpoints along the first and second members and extending downwardly to front feet and upwardly to front seat corners of the chair; 
     b) a rear transverse “X”-shaped structure formed by third and fourth rigid members pivotally coupled scissor-like together at midpoints along the third and fourth members and extending downwardly to rear feet and upwardly to rear seat corners of the chair; 
     c) left and right side “X”-shaped structures each a scissor-like pivotally coupled pair of crossed rigid members, each pair of crossed rigid members having upper and lower oppositely disposed ends pivotally mounted to corresponding ends of the first, second, third and fourth rigid members when the front and rear transverse “X”-shaped structures and the left and right “X”-shaped structures are mounted to one another so as to define a rectangular parallelepiped between the corresponding ends, a sling seat mounted between upper vertices thereof; 
     wherein the improvement resides in at least one telescopic upright support mounted between a front corner of the sling seat and a front foot of the front feet, the front corner of the sling seat and the front foot substantially vertically aligned. 
     The folding chair of the present invention may also include rear uprights mounted to the rear feet and slidably mounted to rear seat corners of the sling seat. The rear uprights may extend above the sling seat to support a backrest mounted therebetween. The folding chair of the present invention is intended to include chairs, stools, folding tables and the like, all collectively alternatively referred to herein as chairs. Thus in a cross-legged scissor-legged folding chair such as found in the prior art, the improvement of the present invention resides in an improved leg supporting apparatus comprising a first upstanding telescopic member mounted between a first corner of a seat portion of the chair and a first foot of the chair, wherein the first upstanding telescopic member telescopically is retracted into a fully retracted position when the chair is unfolded so as to be fully deployed. 
     The folding chair of the present invention may further comprise a second upstanding telescopic member mounted between a second comer of the seat portion and a second foot of the chair, when the second upstanding telescopic member telescopically is retracted into a fully retracted position when the chair is unfolded so as to be fully deployed. Further telescopic upright members may be mounted between the remaining seat corners and feet. 
     Advantageously, the first comer is a front comer and the first foot is a front foot. Similarly, the first and second corners may be front corners and the first and second feet may be front feet. Further advantageously, the first and second upstanding telescopic members are vertical. 
     In one embodiment one ore more of the upstanding telescopic members include a releasable lock mounted thereon or therein to releasably lock the upstanding telescopic member in the fully retracted position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various other objects, features and advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the following detailed description of an illustrative embodiment and the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein; 
     FIG. 1 is a perspective view of prior art folding chair. 
     FIG. 2 is a perspective view of the folding chair of the present invention with telescopic supports and showing the chair deployed. 
     FIG. 3 is a perspective view of the folding chair of the present invention with telescopic Supports extended and showing the chair mostly folded. 
     FIG. 4 a  is a front elevation view of the present invention with telescopic supports and showing the chair deployed. 
     FIG. 4 b  is a section view of the side of the present invention taken from FIG. 4 a  taken along line B. 
     FIG. 5 a  is a side elevation view of the present invention with telescopic supports and showing the chair deployed. 
     FIG. 5 b  is a section view of the front of the present invention taken from FIG. 5 a  taken along line C. 
     FIG. 6 is a perspective view of the folding chair of the present invention in a secondary embodiment with telescopic supports on all four corners. 
     FIG. 7 a  is a close up side cutaway view of the telescopic supports showing the button lock as may be used to lock the telescopic supports when the chair is deployed. 
     FIG. 7 b  is a close up front view of the internal telescopic supports rod with button lock. 
     FIG. 8 a  is a close up front view of the telescopic supports showing the button lock as may be used to lock the telescopic supports when the chair is deployed. 
     FIG. 8 b  is a close up front view of the external telescopic supports tube showing the slot for the button lock. 
     FIG. 9 is a front elevation view of an alternate embodiment with telescopic supports used in three places and showing a love chair deployed. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Folding chair  10  is shown deployed ready for use in FIG.  2 . Folding chair  10  collapses as seen partially collapsed in FIG.  3 . Folding chair  10  may be described as having four frame structures, namely, a front “X”-shaped structure  12 , and a rear “X”-shaped structure  10   14 , and two side “X”-shaped structures  16  and  18  respectively. The corners of the front “X”-shaped structure are pivotally mounted to the front corners of the side “X”-shaped structures. The corners of the rear “X”-shaped structure are pivotally mounted to the rear corners of the side “X”-shaped structures. Thus in the prior art folding seat of FIG. 1, and folding seat  10  of the present invention, when the seats are deployed ready for use, the “X”-shaped structures are spread horizontally until their uppermost corners are restrained from further movement by tensioning of the fabric of the seat suspended between the uppermost corners of all four “X”-shaped structures. 
     As also seen in FIGS. 4 a ,  4   b ,  5   a ,  5   b  and  6 , each “X”-shaped structure is comprised of two elongate rigid members pivotally mounted to each other midway along their lengths. “X”-shaped structure  12  has rigid members  12   a  and  12   b  pivotally mounted to each other by means of pin  12   c . “X”-shaped structure  14  has rigid members  14   a  and  14   b  pivotally mounted to each other by pin  14   c . Left side “X”-shaped structure  16  has rigid members  16   a  and  16   b  pivotally mounted to one another by pin  16   c . Right side “X”-shaped structure has rigid members  18   a  and  18   b  pivotally mounted to one another by pin  18   c . The four “X”-shaped structures  12 ,  14 ,  16  and  18  form a symmetric structure about axis A. The “X”-shaped structures remain symmetrically disposed about axis A during collapsing and deployment of the structure. 
     The improvement over the prior art resides in the addition of at least two telescoping vertical supports  20  and  22 . Vertical support  20  is rigidly mounted between front seat comer  32  and front foot  24 . Vertical support  22  is rigidly mounted between front seat corner  34  and front foot  26 . The upper end of member  12   b  is pivotally mounted to seat comer  32  and the lower end of member  12   a  is pivotally mounted to foot  24  for pivotable motion relative to vertical support  20  in the plane containing front “X”-shaped structure  12 . Similarly, the upper end of member  12   a  is pivotally mounted to seat comer  34  and the lower end of member  12   b  is pivotally mounted to foot  26  for pivotable motion in the plane containing front “X”-shaped structure  12 . 
     Rear “X”-shaped structure  14  is parallel to front “X”-shaped structure  12 . The upper end of member  14   b  is pivotally mounted to rear seat corner  36  and the lower end of member  14   a  is pivotally mounted to rear foot  28 . Rear seat comer  36  is slidably mounted on post  40 . The lowermost end of post  40  is rigidly mounted to foot  28 . The upper end of post  40  supports one side of the webbing of seat back  44   a . The upper end of member  14   b  and the lower end of member  14   a  pivot relative to seat comer  36  and foot  28  respectively in the plane containing rear “X”-shaped structure  14 . The upper end of member  14   a  is pivotally mounted to rear seat comer  38 . The lower end of member  14   b  is pivotally mounted to rear foot  30 . Rear seat comer  38  is slidably mounted on vertical post  42 . Vertical post  42  is rigidly mounted at its lowermost end to foot  30 . Post  42  at its upper end supports the other side of the webbing of seat back  44   a , that is, oppositely disposed to vertical post  40  across the back of the seat. 
     Left and right side “X”-shaped structures  16  and  18  respectively are pivotally mounted at the uppermost ends of their respective rigid members  16   a  and  16   b , and  18   a  and  18   b , to the seat corners  36 ,  32 , and  34  and  38  respectively. They are pivotally mounted for pivotable rotation in the planes containing side “X”-shaped structures  16  and  18  respectively. Similarly, the lowermost ends of members  16   a  and  16   b  are pivotally mounted to feet  24  and  28  respectively, and the lowermost ends of members  18   a  and  18   b  are pivotally mounted to feet  30  and  26  respectively, for pivotal movement in the plane containing side “X”-shaped structures  16  and  18  respectively. 
     Telescoping vertical supports  20  and  22  telescope between a fully extended length and a fully collapsed length. The fully extended length generally corresponds to the corresponding distances between foot  28  and seat comer  36 , and between foot  30  and seat comer  38 , when seat  10  is collapsed inwardly about axis A. When seat  10  is in the fully deployed position, that is, when seat fabric  44  is suitably tensioned for comfortable sitting, telescoping vertical supports  20  and  22  are fully collapsed. Thus a weight, for example, that of a user, suspended in seat fabric  44  may be in part supported by a compression loading of outer tubes or sleeves  20   b  and  22   b  when supports  20  and  22  are telescopically compressed so as to contain the entire length of telescoping rods  20   a  and  22   a  within sleeves  20   b  and  22   b  respectively. 
     As illustrated in FIGS. 7 a ,  7   b , and  8   a ,  8   b , telescoping supports  20  and  22  may include a button lock  48 . Button lock  48  locks the corresponding “X”-shaped structure into its deployed position. Each button lock  48  includes spring  48   a  mounted in the telescoping rod for urging pivotable latch arm  48   c  through an elongate aperture in the rod for latching engagement through a corresponding elongate slot  48   b  in the sleeve sliding over the rod. The latch arm  48   c  and the slot  48   b  in the sleeve align when the telescoping vertical support is fully collapsed so that a compressive loading applied to the support is born against the corresponding foot. Button lock  48  operates on the same principle as an umbrella extension lock. Thus telescoping supports  20  and  22  both limit the compression of the “X”-shaped structures under weight loading and, with the assistance of the button locks, help to keep folding chair  10  fully deployed when a user repositions chair under themselves, for example as will happen when a user pulls the chair closer to a table while still sitting in the chair. 
     As shown in FIG. 6, telescoping supports  20  and  22  may be used on a stool  50 . In this case telescoping supports are used on all four corners. Each telescoping support may include a button lock  48  to lock the “X”-shaped structure in the deployed position, allowing stool  50  to be used as a table. Telescoping supports and corresponding button locks  48  keep flexible seat  52  taut for supporting objects (not shown). 
     In operation, a user grasps front seat corners  32  and  34 , or front feet  28  and  30 , moving them away from each other, expanding each “X”-shaped structure away from axis A, until the expansion of structures  12 ,  14 ,  16  and  18 , is limited by the tensioning of the seat fabric and the telescopic collapse of the vertical supports. To collapse seat  10  the steps are reversed, each “X”-shaped structure collapsing about axis A radially inwardly. 
     Forces from seat  44  imparted to front and rear feet  24 ,  26 ,  28  and  30 , through “X”-shaped structures  12 ,  14 ,  16  and  18  and upright telescopic supports  20  and  22 . Use of supports  20  and  22  relieve the various other components of significant loading. 
     To the accomplishment of the above and related objects, this invention may be embodied in the form illustrated in the accompanying drawings, attention being called to the fact, however, that the drawings are illustrative only, and that changes may be made in the specific construction illustrated and described within the scope of the appended claims.