Abstract:
The present invention is a collapsible stool with a plurality of legs that can be stored either freestanding or hung, and that has a single handle that is used to carry, initiate expansion or collapse of, or used to guide the stool when sitting. Further, the stool has a novel mechanism that allows a smooth transition from collapse to expansion and expansion to collapse using a single handle. This same mechanism allows the stool to stand upright in a stable position in both the expanded and collapsed configurations.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable 
       SEQUENCE LISTING OR PROGRAM 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    Field of Invention 
         [0005]    The present invention relates generally to portable stools and, more particularly, to a collapsible office stool with castering wheels that can be carried and operated by a single handle using a person&#39;s single hand. 
         [0006]    Prior Art 
         [0007]    It is often necessary for people to interact with machines or other people on a temporary basis. These interactions occur in office settings constantly throughout the world. The majority of cases when people interact in an office setting, one person is already seated. For the other person to communicate effectively for all but brief periods, a sitting position is optimum, allowing for both relaxed communication and reduced physical effort on the visiting individual. This situation is especially common in office spaces that have been separated by partitions or cubicles, or in doctors&#39; offices. 
         [0008]    Temporary seating has been around since tools themselves. A four-legged folding stool was proposed in the early part of the last century. See US. Pat. No. 816,158 (Erickson). This stool was designed particularly for camping, used a soft material for the seat, and seemed to require maneuvering of individual parts to erect into a usable device. By 1915 a design was disclosed that collapses a stool into a walking stick. This concept, again, contained a soft seat made of fabric. A reciprocating center rod, combined with straps, synchronized the retraction of four supporting legs. Extending the legs on this design would also require both hands and some maneuvering. See U.S. Pat. No. 1,166,386 (Perrin). 
         [0009]    By 1919 a stool design was suggested that contained three legs and a more substantial seat than its predecessors. This design required complete assembly and disassembly of individual parts to make it usable or compact. See U.S. Pat. No. 1,365,873 (Waderlow). In 1978, a device was presented to provide doctors a seat while performing long procedures. This stool contained three main legs and two auxiliary outriggers for stability. Its size could be reduced by collapsing the legs and outriggers for transportation. This stool was designed to be stationary as it used suction cups to secure the legs to the floor. See U.S. Pat. No. 4,183,579 (Gonzalez). Yet another collapsible stool design with a cloth seat was presented in 1989. This very simplistic design contained a plurality of poles hinged at about their midpoints with ends connected to a common piece of cloth. No reciprocating motion was used to expand or contract the legs. Again, maneuvering would be required using both hands to get this device into a stable seating configuration. See U.S. Pat. No. 4,934,638 (Davis). In 1990, a chair configuration was disclosed that used two hinge lines and a piece of cloth to create collapsible seat. This design is similar to the common lawn chair and has a limited ability to expand wide enough for a stable seating configuration, yet be compact. See U.S. Pat. No. 5,044,690 (Torrey). A portable stool with a single main telescoping support and a plurality of stabilizing legs was disclosed. This stool is designed specifically for outdoor use where a spring-loaded main support provides shock absorption for a sitting person if they should come in contact with an animal or discharge a firearm while seated. The plurality of legs are manually installed using fasteners at the time of use. See U.S. Pat. No. 6,062,638 (Ferguson). Another outdoor seating design was disclosed in 2005 that uses a single pole extending from a seat to the ground that provides a means supporting one&#39;s weight while fishing or other outdoor activity. This design is compact but has no means of providing stability. See US. Pat. No. 2005/0242630 (Miller). 
       OBJECTS AND ADVANTAGES 
       [0010]    The present invention is a rolling stool of stable configuration that collapses and expands by raising or lowering a single handle at the front of its seat using a person&#39;s single hand. Further, the invention can be carried by the same handle without the need to use one&#39;s other hand at any point. 
         [0011]    A normal cycle of use for the present invention is as follows. The stool is hanging on a cubicle partition or door by its storage guide, or standing collapsed in a corner of the room with its handle easily accessed in the vertical position. A person, who may have one hand full, grabs the stool by the handle and picks it up from its stowed location. The stool maintains its collapsed position under the load created internally between the handle and its own weight. The person walks to a location they prefer to sit, carrying the stool like a briefcase. On location, the stool is set on the ground in front of them and gentle downward pressure is applied to the handle to lower it. This causes the stool to unfold its legs to create a stable seating platform. At the same time, the seat rotates from a near vertical to a horizontal position. The stool can then be used to sit and roll around a vicinity on its plurality of casters, using the handle to help guide its motion, which will be between the knees of the sitting person. When someone is done sitting, they can simultaneously dismount the stool, stand, and pick up on the stool&#39;s handle. The upward force on the handle will automatically fold the stool into a collapsed position. It is ready to be carried to a desire location and hung or set down on the floor. Only a single hand of the person is needed throughout the whole process, leaving the other hand free to carry business related materials. Since the stool is stable in both collapsed and extended positions, it can be place on any level floor in either position until ready for use. In its collapsed position, the stool can be hung on a cubicle partition, a door, or any other rigid vertical structure. Or, it can stand nicely in the corner of an office without the need to rest against a wall for stability. 
         [0012]    Part of the novelty of the present invention is the single handle operation that takes only one hand to expand, collapse and transport the stool. What is not obvious is the unique kinematics of the stool&#39;s folding mechanism. A plurality of double-wheeled casters are used to allow translation, while sitting on the stool, but they also work as a component of a smooth folding mechanism. As the stool is placed on the ground, the hinge line of each caster is above the wheels&#39; contact point. If the casters contained single wheels, they would be unstable and flip around at first contact. (Refer to  FIGS. 12 through 14 ) The present invention&#39;s novel mechanism allows the stool to smoothly unfold its legs as the casters roll across the floor&#39;s surface. The mechanism&#39;s geometry and the double-wheels of the casters allow local stability of each caster as they transition into a position with their pivot axis in a vertical orientation as the stool is unfolded. This is one unique feature of this stool that is not obvious at first inspection. This same local stability of each double-wheeled caster allows the stool to sit on the ground in the collapsed configuration without failing over, while a slight downward pressure on the handle causes the seat to go from a near vertical to a horizontal position as the stool unfolds all of its components in complete unison. 
       SUMMARY OF INVENTION 
       [0013]    The present invention is a collapsible stool with a plurality of legs that can be stored either freestanding or hung, that contains a single handle that is used to carry, initiate expansion or collapse of, or used to guide the stool when sitting. Further, the stool has a novel mechanism that allows a smooth transition from collapse to expansion and expansion to collapse using a single handle. This same mechanism allows the stool to stand upright in a stable position in both the expanded and collapsed configurations. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of the present invention in the expanded position. 
           [0015]      FIG. 2  is a perspective view of the present invention in the expanded position showing the lower side. 
           [0016]      FIG. 3  is a perspective view of the present invention in an intermediate position between expanded and collapsed. 
           [0017]      FIG. 4  is a perspective view of the present invention in a collapsed position showing the lower side of the seat. 
           [0018]      FIG. 5  is a perspective view of the present invention in a collapsed position showing the upper side of the seat. 
           [0019]      FIG. 6  is a side elevation view of the present invention in an expanded position. 
           [0020]      FIG. 7  is a side elevation view of the present invention in a collapsed position. 
           [0021]      FIG. 8  is a back elevation view of the present invention in a collapsed position. 
           [0022]      FIG. 9  is a front elevation view of the present invention in a collapsed position. 
           [0023]      FIG. 10  is a plan view of the present invention in an expanded position. 
           [0024]      FIG. 11  is a lower plan view of the present invention in an expanded position. 
           [0025]      FIG. 12  is a side elevation view of the caster positions of the present invention while sitting on the ground or hanging from its storage guide. 
           [0026]      FIG. 13  is a side elevation view illustrating three intermediate caster positions of the present invention as it is being collapsed while still touching the floor. 
           [0027]      FIG. 14  is a side elevation view illustrating three intermediate caster positions of the present invention as it is being expanded while resting against the floor. 
           [0028]      FIG. 15  is a section view illustrating the novel hinge mechanism used to attach each leg of the stool efficiently and without fasteners. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    The preferred embodiment of the invention consists of a seat  101 , with a handle  41  at its forward end, that is fastened to a seat beam assembly  103 , which is connected to a support beam assembly  105  by a hinge that pivots about a seat hinge pin  27 . The seat beam assembly  103  contains a storage guide  43  that stabilizes the stool as it rests on a partition, door, or other rigid structure in the collapsed position. A plurality of legs  15 , made from hollow aluminum square tubes, are each attached to the lugs of a slider fitting  13  through hinges pivoting about a plurality of leg hinge pins  25  and a lower link hinge pin  35 . The legs  15  extend radially and each fasten to a caster fitting  17  with two rivets  45 . Each caster fitting  17  attaches a caster  21  with double-wheels to one of the legs  15  by screwing the shank of the caster  21  into a threaded hole. A plurality of tension links  23  connect to each of the caster fittings  17  at hinges connected by a plurality of outer link hinge pins  33 . Each of the tension links  23  connect to a single tension fitting  19  by hinging about a plurality of inboard link hinge pins  31  installed into each pair of lugs as part of the tension fitting  19 . The tension fitting  19  slides over and is riveted to a support tube  39  that is part of the support assembly  105 . The slider fitting  13  contains a center hole large enough to accept a pressed-in bearing of fiber-reinforced plastic with an inner diameter slightly larger than the support tube  39  as to allow vertical movement along the tube. The upmost vertical movement of the slider fitting  13  is restricted by a tube stop  37  welded to the support tube  39 . Downward movement of the slider fitting  13  is restricted by the tension fitting  19  or by other restrictions in the system such as caster  21  to caster  21  contact, when collapsed. A main link  11  connects the slider fitting  13  to the seat beam assembly  103  by hinges that pivot about a lower link hinge pin  35  and an upper link hinge pin  29 , respectively. The present invention uses sintered bronze plain bearings to support all large hinge pins in the slider fitting  13 , main link  11  and seat beam assembly  103 . Teflon coated plain bearings are used to support smaller hinge pins connecting the tension links  23 . Small pins are retained by applying retaining compound to and pressing them into interference-sized holes in the caster fittings  17  and the tension fitting  19 . The preferred embodiment of the present invention uses a seat  101  made of fiber-reinforced plastic, or composite, that contains the handle  41  integral to its structure. The support tube assembly  105  is preferably made of steel with surface treatment or stainless steel. Each of the pins are preferably made from steel or stainless steel. All other parts are preferably made from aluminum. 
         [0030]    The leg hinge pins  25  are held in place by applying retaining compound and pressing each into the inside of a metal tube  49 , preferably made of aluminum, swaged into a through-hole in each of the legs  15 . (Refer to  FIG. 15 ) A set of plain bearings  45 , preferably made of sintered-bronze, are used as rotational surfaces for each pin, while flat washers  47  are used to bear lateral thrust loads. The upper link hinge pin  29  is coated with retaining compound and pressed through an under-sized tube  51  that retains the pin. The seat hinge pin  27  has retaining compound applied to and is pressed into an interference-sized steel tube that rests in holes of, and tack welded into, the support tube  39  perpendicular to its centerline axis. All large pins, preferably, rotate on sinter-bronze bearings. 
         [0031]    An alternate embodiment of the present invention uses a linear roller bearing pressed into, or otherwise captured by, the slider fitting  13  that rides on the support tube  39  made from hardened steel or steel with hardened surface. Each caster  21  may be attached by means threading, or held into the caster fitting  17  by a friction device. 
         [0032]    Another embodiment of the present invention uses legs  15  of a different section shape than the preferred square-shape. Tension links  23  could also be made using a different section shape than the I-shape in the preferred embodiment. All parts could be made from an alternate material such as titanium, aluminum, steel, plastic, fiber-reinforced plastic, plastic, or otherwise. Also, rotational bearings, plain, spherical, roller, ball-type, may or may not be used between each hinge pin and each lug. Hinge pins could be replaced by alternate fasteners such as bolts, rivets or otherwise. 
         [0033]    Still another embodiment of the present invention uses a seat  101  of different shape yet contains a handle  41 , either integral, as used in the present invention, or attached, as to allow collapse and expansion of the stool using a single hand. The storage guide  43  may also be in a different shape, either integral or affixed, yet function in a similar manner, as to stabilize the stool as it sits on a partition, door, or other rigid structure in the collapsed position. 
         [0034]    While the preferred embodiment uses five legs  15  and associated linkages, other embodiments may have fewer or greater legs. While a greater number of legs will increase tip-over stability for a given leg length and geometry, it comes with added complexity and weight. 
         [0035]    The present invention uses a reciprocating motion of the slider fitting  13  to synchronize the extension and collapse of all five leg  15 . The relationship of the slider fitting  13  to the tension fitting  19  along the length of the support assembly  105  determines the positions of the legs  15  and tension links  23 . When the legs  15  of the stool are fully extended, the slider fitting  13  rests against the tube stop  37  and the seat  101  is in a horizontal position. The main link  11  connects the seat beam assembly  103  to the slider fitting  37  and synchronizes the rotational motion of the seat  101  to the extension of the leg  15  and supporting structure. To collapse the stool, the handle  41  is raised, simultaneously breaking down the leg support trust structure and raising the seat. As the front of the seat  41  is raised, weight of the stool is still resting on the casters  21 . As the legs  15  are drawn inward, the casters  21  rotate so that they trail radially outward. (Refer to  FIG. 13 ) The caster&#39;s pivot axis moves from vertical to somewhere between vertical and horizontal when the leg  15  are fully collapsed. The positions of the casters  21  remain stable from gravity once lifted from the floor. If the stool is place back onto the floor, the casters  21  remain in these positions because of the unique orientation the caster fittings  17  place the casters  21  in. Even with the caster pivot axis above the contact points of the wheels to the floor, the casters  21  remain in position, supporting the weight of the stool in the collapsed position. If slight downward pressure is applied to the stool&#39;s handle  41 , the legs  15  of the stool will extend outward, yet the casters  21  will remain in the same radial position and support the weight of the stool as its legs  15  are being extended. Only when the legs  15  are almost fully expanded and the tension links  23  are near horizontal, will the casters  21  begin to flip around seamlessly. (Refer to  FIG. 14 ) This novel mechanism allows for a smooth transition from collapsed to expanded and expanded to collapsed configurations of the stool. It also allows the stool to be placed on the floor in the collapsed position while supporting its own weight. 
         [0036]    Another embodiment of the present invention may arrange the linkages so that contact points of each caster  21  to the ground, while in the collapsed stool position, are radially outboard from the center&#39;s of the leg hinge pins  25  and  35 . This will allow the stool to unfold as it is placed on the floor without downward pressure on the handle  41 . The stool will then be required to hang by the storage guide  43  when not in use. 
         [0037]    The forgoing is considered as illustrative only to the principal of the invention. Further, since numerous changes and modification will occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described above, and accordingly, all suitable modifications and equivalents may be resorted to falling within the scope of the invention.