Indexing seat for folding chair

A folding chair has a support structure with a back support portion and leg supports. A stabilizing seat is pivotally coupled to the support structure. The seat has a seating surface, and at least one upper projecting alignment member configured to substantially engage a second chair to stabilize and prevent relative lateral movement between the two chairs when in a folded and stacked relationship.

BACKGROUND OF THE INVENTION
 1. The Field of the Invention
 The present invention relates generally to a folding chair, and/or a
 stackable/storable folding chair system. More particularly, the present
 invention relates to a folding chair having a seat with a projecting
 alignment member, such that a number of folded chairs may be stacked
 adjacent one another with the projecting alignment member of the seat
 engaging or nesting with the support frame of an adjacent stacked chair
 for stability.
 2. The Background Art
 Folding chairs are often used in situations in which it is desirable or
 necessary to provide varying numbers and/or varying layouts of chairs,
 such as during conventions, seminars, conferences, etc. In addition,
 folding chairs are often used in multipurpose areas in which patron
 seating is required for some functions, but a large open space is required
 for other functions necessitating storage of the chairs. For example, some
 organizations have buildings with a multipurpose room which may be used
 for banquets, seminars, conventions, etc., with chairs set up, or for a
 dance, sporting event, etc., with the folding chairs removed.
 It is desirable that the folding chairs be capable of being folded and
 stacked for storage so that the chairs take up less room when they are not
 required. It will be appreciated that some situations or events will
 require thousands of folding chairs, all of which may need to be folded
 and stored at any given period. Thus, the chairs must be folded and stored
 such that they have a high storage density to minimize the storage space
 required. It will be appreciated that any extra thickness of a chair when
 folded becomes significant when numerous folding chairs are involved. For
 example, with a thousand stacked folding chairs, a folding chair which
 saves one extra inch in the folded position results in over 80 linear feet
 of saved storage space.
 One disadvantage with many prior art folding chairs is the bulk or
 thickness of the chair in the folded position. Many typical folding chairs
 still remain several inches thick in the folded position, and thus are
 less dense when stored. For example, many typical folding chairs have
 seats which fold adjacent to or abutting the legs, and/or have front and
 back legs which fold against one another, such that the thickness of the
 chairs in the folded position comprises the thickness of both the front
 and rear legs, and/or the thickness of the legs and the seat. Another
 disadvantage of many conventional folding chairs is that they fold
 awkwardly, with bulky folded configurations and/or various protruding
 members.
 In addition, it is desirable that the folding chairs be easily storable or
 stackable, and be stable when stored/stacked. Many typical prior art
 folding chairs are stored merely by leaning one chair against a wall and
 subsequent chairs in a series against the first chair. It will be
 appreciated that a plurality of folding chairs stacked against a wall have
 a potential domino effect, with all of the chairs subject to being knocked
 over. Other prior art folding chairs have complicated and expensive
 hanging rack systems. For example, a wheeled cart might have a plurality
 of support arms from which a plurality of folding chairs are suspended.
 One disadvantage of these types of systems is that chairs on the end of
 the hangers tend to fall off the rack, and the wheeled racks are difficult
 to move and maneuver.
 Some types of prior art folding chairs have back rest portions which
 protrude from the chair and into an adjacent folding chair. For example, a
 folding chair may have a back portion which curves outwardly to protrude
 from the frame of the chair, and into the frame of and adjacent folding
 chair. Although this relationship allows the chairs to be stored with
 greater density, the chairs tend to be unstable in a stored position. The
 broad rounded backs of the chairs act as ramps which fail to resist
 movement of an adjacent chair. In addition, the chairs are still
 relatively thick and bulky.
 It also is desirable that the chairs be easy to set up and take down, or
 fold and unfold. It will be appreciated that there is considerable time
 involved in setting up and taking down thousands of chairs. One
 disadvantage of many prior art folding chairs is that they are difficult
 to both unfold and fold. For example, most folding chairs require the
 person to use both hands to fold and unfold the chair. One hand usually
 has to grasp the back of the chair while the other hand has to grab and
 pivot the seat in or out.
 It also is desirable that the chairs be comfortable. Typical prior art
 folding chairs have rigid metal seats and seat backs which can be hard and
 uncomfortable. One disadvantage of many prior art folding chairs is that
 the chairs either fold well and are uncomfortable, or are comfortable but
 awkward in folding. Thus, there tends to be a trade off between comfort
 and foldability. Some chairs provide a cushion. But these chairs still
 utilize the rigid metal seat bottoms and seat backs, and the cushions tend
 to make the chairs even thicker when folded.
 In addition, it is desirable that the chair provide proper support, or be
 ergonomically designed. One disadvantage of many prior art chairs is that
 the angle between the back rest and the seat is dictated by the folding
 mechanism of the chair. Thus, in an effort to create a folding chair, the
 proper ergonomic design of the back rest and seat is often compromised in
 order to obtain a chair that folds more easily.
 Another disadvantage of many typical prior art folding chairs is that they
 have a relatively small back support which may not adequately support a
 user's back. The small back support is often a function of the folding
 configuration of the chair. Again, the back support is often compromised
 in order to obtain a chair that folds. For example, the seat may be
 configured to fold upwardly or towards the back support, so that a
 relatively large space must exist between the back support and the seat so
 that the seat may fold into that space. That space is usually located
 where a user requires back support.
 It also is desirable that the folding chair be durable. It will be
 appreciated that the chair will be alternately stored and used, folded and
 unfolded, innumerable times. Similarly, it is desirable that the folding
 chair be strong. The chair must be able to support persons of various
 weight, often in potentially abusive conditions.
 It also is desirable that the folding chair be safe. It will be appreciated
 that as the various parts of the chair fold, there is a potential for
 fingers and the like to become pinched within the folding mechanisms.
 Therefore, it would be advantageous to develop a folding chair capable of
 folding for high density storage. It also would be advantageous to develop
 such a folding chair which is more stable and safe in the folded and
 stored position. It would further be advantageous to develop a folding
 chair which (i) may easily be folded and unfolded; (ii) is comfortable and
 safe; (iii) is durable, strong, and cost effective.
 OBJECTS AND SUMMARY OF THE INVENTION
 It is therefore an object of the present invention to provide a folding
 chair which folds relatively thin to maximize storage density.
 It is another object of the present invention to provide such a folding
 chair which stores safely and is stable when stored, and/or stacked.
 It is another object of the present invention to provide a folding chair
 which is easily folded and unfolded.
 It is yet another object of the present invention to provide a folding
 chair which is safe and comfortable.
 It is yet another object of the present invention to provide a folding
 chair which is durable, strong, and cost effective.
 The above objects and others not specifically recited are realized in a
 specific illustrative embodiment of a folding chair having a folding,
 stabilizing seat. The chair includes a support structure having a back
 support portion and leg supports. The stabilizing seat is pivotally
 coupled to the support structure.
 The seat has a seating surface, and at least one upper projecting alignment
 member. The alignment member is configured to substantially engage a
 second chair to stabilize and prevent relative lateral movement between
 the two chairs when in a folded and stacked relationship.
 In accordance with one aspect of the present invention, the upper
 projecting alignment member protrudes from a rear corner of the seat. In
 addition, two upper projecting alignment members may each protrude from a
 rear corner of the seat.
 In accordance with another aspect of the present invention, the upper
 projecting alignment member is integrally formed with the seating surface.
 The integral, upper projecting alignment member protrudes substantially
 perpendicular to the seat surface. The integral alignment member may
 include a seating curvature forming a continuous extension of the seating
 surface.
 In accordance with another aspect of the present invention, a majority of
 the stabilizing seat collapses into a volume defined by the support
 structure with the upper projecting alignment member protruding therefrom
 to engage another chair. The upper projecting alignment member nests with
 the support structure of the second adjacent and stacked chair.
 Additional objects and advantages of the invention will be set forth in the
 description which follows, and in part will be apparent from the
 description, or may be learned by the practice of the invention without
 undue experimentation. The objects and advantages of the invention may be
 realized and obtained by means of the instruments and combinations
 particularly pointed out in the appended claims.

DETAILED DESCRIPTION
 For the purposes of promoting an understanding of the principles in
 accordance with the invention, reference will now be made to the
 embodiments illustrated in the drawings and specific language will be used
 to describe the same. It will nevertheless be understood that no
 limitation of the scope of the invention is thereby intended. Any
 alterations and further modifications of the inventive features
 illustrated herein, and any additional applications of the principles of
 the invention as illustrated herein, which would normally occur to one
 skilled in the relevant art and having possession of this disclosure, are
 to be considered within the scope of the invention claimed.
 As illustrated in FIG. 1, a folding chair, indicated at 10, in accordance
 with the present invention, is shown in a first, open, unfolded
 orientation or position. The folding chair 10 advantageously has a
 folding, stabilizing seat 50 with an upward projecting alignment member
 200 to stabilize and prevent relative lateral movement between two folded
 and stacked chairs, as described in greater detail below.
 As indicated above, typical prior art chairs fold into a thick, awkward or
 bulky shape or configuration, or have significant protruding members, such
 that typical prior art folding chairs are less dense when stored, and
 require more space for storage. The folding chair 10 of the present
 invention utilizes a new approach in which the chair 10 is designed or
 configured to fold or collapse into a minimum thickness, such that the
 chairs 10 of the present invention have a very high storage density, while
 still providing strength, comfort, and durability. Thus, when folded, the
 chair 10 of the present invention advantageously is thin or presents a
 minimal profile, as shown in FIG. 3. In addition, the thin profile of the
 chair 10 advantageously is shaped or configured to facilitate nesting or
 indexing with adjacent chairs, as shown in FIG. 4.
 The shape of the thin profile of the chair of the present invention 10 may
 take various configurations, as described in co-pending U.S. patent
 application Ser. No. 09/425,586, filed Oct. 22, 1999 which is herein
 incorporated by reference.
 Referring to FIGS. 1 and 2, the folding chair 10 has a rigid support frame
 14 including left and right, or first and second, rigid side supports 18
 and 20, as shown in FIG. 1. As indicated above, it is desirable that the
 chair 10 be durable and strong. Thus, the rigid nature of the support
 frame 14 increases the durability and strength of the chair 10.
 Preferably, the support frame 14 is formed from a tubular material to
 optimize strength and weight. In addition, the tubular material preferably
 has an elongated cross-sectional shape which is oriented generally
 vertically to increase the weight capacity of the chair 10. Furthermore,
 the tubular material preferably has rounded corners, or most preferably
 has an oval cross-sectional shape, giving soft edges to the frame 14 which
 are more comfortable.
 The support frame 14, and side supports 18 and 20, have an upper back
 support portion 24 forming the back of the chair 101 and a lower front leg
 portion 28 formed integrally and continuously with the upper back support
 portion 24. The back support portion 24 extends forwardly from the back of
 the chair 10 to the lower front leg portions 28. Thus, the first and
 second side supports 18 and 20, or the upper and lower portions 24 and 28
 thereof, are unitary, integral, and rigid structures to increase strength
 and durability. The front leg portion 28 preferably includes left and
 right, or first and second, front legs 32 and 34. In addition, the support
 frame 14, or side supports 18 and 20, may be a single integral member with
 a broad curved back member 36 formed at the tops of the side supports 18
 and 20, as shown.
 As indicated above, the rigid support frame 14 preferably is shaped to form
 a curved spline profile. As used herein, the term "curved spline" is used
 broadly to describe an elongated member with at least a curved portion,
 and which may include multiple curves and/or straight portions as well.
 The profile is an elongated continuous profile having a substantially
 uniform thickness which is relatively thin when all elements are collapsed
 within the profile. The thin uniform profile contributes to a higher
 storage density of the chairs.
 The chair 10 also includes a rear leg portion 38, which preferably includes
 left and right, or first and second, rear legs 40 and 42, as shown in FIG.
 1. The rear leg portion 38, or rear legs 40 and 42, are pivotally coupled
 to the support frame 14 at leg pivot points 46. The leg pivot points 46
 are preferably fixed pivot points, such that the rear legs 40 and 42 pivot
 with respect to the support frame 14 or front legs 32 and 34.
 In addition, the chair 10 includes a seat or seat portion 50 pivotally
 coupled to the support frame 14, and between the side supports 18 and 20
 at seat pivot points 54. Again, the seat pivot points 54 are preferably
 fixed pivot points such that the seat 50 pivots with respect to the
 support frame 14, rather than sliding. The seat 50 and rear legs 40 and 42
 also are pivotally connected as discussed in greater detail below.
 The seat 50 may comprise a seating surface 51 secured to a seat frame 52.
 The seat frame 52 may extend generally around the perimeter of the seat
 50, or along the sides, front and back of the seat 50. This provides an
 advantage where the seat may flex in response to a load, as discussed
 below. The seating surface 51 is disposed on the seat frame 52, and spans
 the distance between the perimeter of the frame 52. Preferably, the
 seating surface 51 is formed of a flexible material, and flexes, bends, or
 deflects downwardly and into the seat frame 52 in response to, and
 proportional to, a user's weight. The flexibility of the seating surface
 51 is enabled because of the perimeter location of the seat frame 52, and
 allows the seating surface 51 to cup or curve, and thus conform to the
 user for a custom fit. In addition, the seating surface 51 preferably is
 coupled to the seat frame 52 only at the front and back, and not at the
 sides, to further allow the seat surface 51 to deflect.
 The seat 50 and rear legs 40 and 42 pivot with respect to the support frame
 14 between (i) the first, open, unfolded position, as shown in FIGS. 1 and
 2, and (ii) the second, closed, folded position, as shown in FIG. 3. The
 leg pivot points 46 preferably are located on a straight section of the
 support frame 14, or first and second side supports 18 and 20, or at a
 mid-section of the composite curve. Thus, holes for the pivot points 46
 may be formed in the side supports 18 and 20 prior to bending the support
 frame 14 during the manufacturing process. If the holes are located on
 curved portions of the support frame 14, then forming the holes prior to
 bending may cause the holes to be mis-shaped as the curve portion of the
 support frame is formed.
 The location of leg pivot points 46 facilitates a chair having a curved
 spline. By locating the pivot points 46 at the mid-section of a composite
 curve, or at the intersection of two linear members, the relative shear
 and load stresses (combined stresses), as well as the strain, in the frame
 14 are at a minimum. The stress is high at the leg pivot points 46 because
 the real legs 40 and 42 act as lever arms to concentrate the force.
 Referring to FIG. 3, the seat 50 and rear legs 40 and 42 advantageously
 pivot such that a majority of the seat 50 and a majority of the rear legs
 40 and 42 collapse within a volume defined by the support frame 14. Thus,
 in the folded position, the chair 10 substantially maintains the curved
 spline profile of the support frame 14. The chair 10 (or the support frame
 14, seat 50 and rear legs 40 and 42) also advantageously has a curved
 spline profile in the closed position, with the profile having a
 substantially uniform thickness which is relatively thin. The volume
 defined by the support frame 14 is the space between the side supports 18
 and 20. Thus, the seat 50 and rear legs 40 and 42 pivot such that a
 majority of the seat 50 and rear legs 40 and 42 fold directly between the
 side supports 18 and 20.
 The seat 50 and rear legs 40 and 42 collapsing within the volume of the
 frame 14 provides a distinct advantage over prior art folding chairs, in
 which the seat and legs fold inwardly and onto the frame such that the
 frame, legs and seat form a relatively thick stack. In addition, the
 curved spline profile of the chair 10 in the folded position provides a
 distinct advantage over the prior art chairs, in which the profiles are
 straight and/or bulky. The chairs 10 of the present invention are capable
 of not only folding into a relatively thin profile in order to save
 storage space, but also forming a continuously and similarly shaped
 profile in which the profiles of adjacent chairs may be matched or nested
 to increase stability of the chairs in a stacked and stored relationship.
 As illustrated in FIG. 4, a storable folding chair system, indicated
 generally at 60, may include a plurality of the above described chairs,
 including, for example, a first chair 10 and a second chair 62. The curved
 spline profile of the first folded chair 10 nests or indexes with the
 curved spline profile of the second folded chair 62 to resist relative
 motion of the two chairs 10 and 62 when disposed adjacent one another in
 an adjacent storage relationship. Referring again to FIG. 3, the curvature
 of the profile creates a protrusion or protruding portion 66 of the
 profile and an opposite matching indentation or recess 68 in the profile
 as the profile deviates from a straight line into a curvature. Thus,
 referring to FIG. 4, the protrusion 66 of the profile of the first chair
 10 nests or indexes within the indentation or recess 68 of the profile of
 the second chair 62. Unlike many prior art folding chairs, which include a
 backrest portion which protrudes from the straight thick profile of the
 chair into the straight thick profile of an adjacent chair, the entire
 profile of the chair 10 of the present invention simultaneously forms the
 protrusions 66 and indentations 68 such that it is the entire profile of
 the chairs 10 and 62 which match to nest.
 Referring again to FIGS. 1 and 2, the front legs 32 and 34 are preferably
 curved, and may be convex, as shown. The rear legs 40 and 42 are
 advantageously similarly curved so that the rear legs 40 and 42 may
 substantially collapse within the volume defined by the front legs 32 and
 34. Both the front and rear legs 28 and 38 have a radius of curvature,
 with the radius of curvature 27 of the rear legs 40 and 42 being smaller
 than the radius of curvature 29 of the front legs 32 and 34. The smaller
 radius of curvature 27 of the rear legs 40 and 42 allows a greater portion
 of the rear legs 40 and 42 to collapse within the volume defined by the
 front legs 32 and 34.
 Referring to FIG. 3, the smaller radius of curvature of the rear legs 40
 and 42 also allows a portion of the bottom ends 72 of the rear legs 40 and
 42 to protrude or extend outside the volume defined by the front legs 32
 and 34. Although it is desirable to have a majority of the seat 50 and
 rear legs 40 and 42 collapse within the profile of the frame 14, the
 bottom ends 72 of the rear legs 40 and 42 extend outside of the volume of
 the front legs 32 and 34 to increase the stability of multiple stacked
 chairs. Referring to FIG. 4, it can be seen that the bottom ends 72 of the
 rear legs 42 of the first chair 10 protrude slightly from the profile,
 specifically of the front legs 34, of the first chair 10, and into the
 profile of the second chair 62. Therefore, the curved spline profile of
 the chairs 10 and 62 resists relative movement between the two chairs 10
 and 62 in a longitudinal direction (or top to bottom direction), and the
 bottom end 72 of the first chair 10 protruding into the profile of the
 second chair 62 resists lateral relative motion (side-to-side) between the
 two chairs 10 and 62.
 The folding chair 10 also includes left and right, or first and second
 folding systems, represented by the second or right folding system 100,
 formed by and pivotally coupling the frame 14, seat 50 and respective
 first and second rear legs 40 and 42 together, as described in co-pending
 U.S. patent application Ser. Nos. 09/425,580, filed Oct. 22, 1999,
 entitled "FOLDING MECHANISM FOR FOLDING CHAIR", and 09/425,577, filed Oct.
 22, 1999, entitled "FOLDING MECHANISM WITH KICK-OUT TAB FOR FOLDING
 CHAIR", which are herein incorporated by reference. The folding system 100
 allows the various components of the chair 10 to fold as thinly as
 possible in the folded position, and provides strength to the seat in the
 open position.
 In addition, the folding chair 10 includes a flexible back support 156
 coupled to the upper back support portion 24 of the support frame 14, and
 a lower lumbar region or member 160, as described in co-pending U.S.
 patent application Ser. No. 09/425,596, filed Oct. 22, 1999, entitled
 "FOLDING CHAIR WITH LUMBAR SUPPORT AND FLEXIBLE BACK SUPPORT", which is
 herein incorporated by reference.
 As described above and illustrated in FIG. 4, the stackable/storable
 folding chair system 60 of the present invention includes a plurality of
 folding chairs 10 and 62 of similar geometry with profiles that nest to
 prevent relative movement in at least one direction. Referring to FIGS. 1
 and 5, the folding chair 10 has an upward projecting alignment member 200
 associated with the seat 50 or seat surface 51. The alignment members 200
 preferably are formed in the rear corners of the seat surface 51, and
 extend or protrude generally perpendicular to the seat surface 51.
 Referring to FIG. 5, the seat surface 51 and seat structure 52 may be
 broadly concave for a comfortable contour. The alignment members 200 may
 be formed flush with the upward surface of the seat surface 51, and
 continue the concave curvature of the seat surface 51 to project upwardly
 at the sides of the seat 50 and at the back. Thus, the curvature of the
 alignment members also adds to the contour and comfort of the seat 50.
 Referring now to FIG. 6, the alignment member 200 is shaped, sized and
 located to substantially engage an adjacent stacked chair 62 to stabilize
 the chairs 10 and 62 relative to one another, and to resist relative
 lateral movement between the two chairs 10 and 62. Thus, although the seat
 50 substantially collapses within the volume defined by the frame 14, the
 alignment members 200 protrude or project upwardly from the volume defined
 by the first chair 10 to extend into the volume defined by the support
 frame 14 of the second chair 62, and for engaging the support frame of the
 second chair. Thus, the alignment members 200 provide the dual purpose of
 adding to the comfortable contour of the seat surface 51, and stabilizing
 adjacent stacked chairs.
 In addition, while the profile of the chairs 10 and 62 resist longitudinal,
 or up and down, relative motion between the chairs, and the projecting
 lower end 72 of the rear legs 40 and 42 resist lateral, or left and right,
 relative motion, the alignment members 200 of the seat 50 further resist
 lateral, or side to side, relative movement of the chairs 10 and 62 near a
 mid-section of the chairs. Thus, the lower protruding end 72 of the rear
 legs 40 and 42 and the alignment members 200 of the seat 50 combine to
 create multiple points of stability along the adjacent stacked chairs.
 Alone, the protruding lower portion 72 of the rear legs 40 and 42 resist
 lateral relative motion at the bottom of the adjacent stacked chairs,
 while the tops may tend to displace laterally, resulting in a pivotal or
 rotational movement between the chairs. Similarly, the alignment members
 200 of the seat 50 prevent lateral relative movement at a mid-section of
 the chairs alone, although the upper and lower ends may tend to move,
 resulting in a pivotal or rotational movement. Thus, the protruding lower
 end 72 of the rear legs 40 and 42 and the alignment members 200 of the
 seat 50 together resist both lateral and rotational movement.
 In addition, the folding chair 10 may include front and rear indexing feet
 210 and 214, as described in co-pending U.S. patent application Ser. No.
 09/425,264, filed Oct. 22, 1999, entitled "INDEXING FEET FOR FOLDING
 CHAIR", which is herein incorporated by reference.
 It is to be understood that the above-described arrangements are only
 illustrative of the application of the principles of the present
 invention. Numerous modifications and alternative arrangements may be
 devised by those skilled in the art without departing from the spirit and
 scope of the present invention and the appended claims are intended to
 cover such modifications and arrangements. Thus, while the present
 invention has been shown in the drawings and fully described above with
 particularity and detail in connection with what is presently deemed to be
 the most practical and preferred embodiment(s) of the invention, it will
 be apparent to those of ordinary skill in the art that numerous
 modifications, including, but not limited to, variations in size,
 materials, shape, form, function and manner of operation, assembly and use
 may be made without departing from the principles and concepts set forth
 herein.