HIGH DENSITY STACKING FLEX CHAIR

Abstract: A high density stacking flex chair is disclosed. A one-piece frame (10) has a seat portion (20) attached thereto, and a back portion (30) pivotally attached thereto. The back portion (30) is curved and can tilt backwards, but is limited by the frame (10) which, through the back portion (30), has a lesser radius of curvature and is angled downward, thus providing stop action for back portion rotation.

Description: HIGH DENSITY STACKING FLEX CHAIR This application is a continuation-in-part of co-pending application Serial No. 381,581, filed May 2, 1989 which was in turn a continuation-in-part of Serial No. 185,707, filed April 25, 1988, now abandoned. BACKGROUND Field of the Invention The present invention relates to chair design, more specifically, to a design for a high density stacking chair with a tilting back. Discussion of the Prior Art The use of low-cost, stacking chairs is well- known in the art. However, such chairs are designed not with comfort or ergonomics in mind, but rather to provide a large quantity of temporary seats for occasional use which can ordinarily be stored and take up minimal storage space. Such chairs may have some limited flexibility in the seat back portion, but provide no ergonomic benefits. Considerable attention has been focused in recent years on better ergonomic designs, resulting in home and office chairs which demonstrate a wide variety of designs which include the ability to recline and provide lumbar support. See, for example, U.S. Patent No. 4,732,424. Such ergonomic designs do not, however, provide low cost seating. Thus, it would be desirable to combine the benefits of ergonomic design into a low cost, stackable chair. SUMMARY OF THE INVENTION A high density stacking chair with a tiltable back portion is presented, wherein a single continuous frame is provided, having a seat portion attached thereto, and a back portion pivotally attached thereto. Ergometric adjustment of the chair is accomplished by tilting of the back portion and flexure of the frame, and flexure of the frame urges the back portion into a normal upright position for stacking and uniform appearance. The back portion is curved and hollow, and engages the frame at upper and lower curved sections of the frame, which sections have radii of curvatures less than that of the back portion and which sections are positioned at a downward angle such that the effective horizontal radii of the sections in the upright position is shorter than the actual radii, causing the back portion to rest against the curved sections and limit forward tilting of the chair back. When the back portion is tilted, the radial movement disengages the back portion from the curved sections due to the difference in radii, until the angle of tilt is such that the effective radii are again equal and the back portion again rests against the curved sections of the frame and limits tilting backward. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description of the invention and accompanying drawings which set forth an illustrative embodiment in which the principles of the invention are utilized. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a chair built according to the present invention. Fig. 2 is the preferred embodiment of a chair built according to the present embodiment. Figs. 3-5 are views taken across section 3-3 of Fig. 1 and showing the chair extending through its range of backward tilt. Fig. 6 is a view taken across Section 6-6 of Fig. 4 and represents a plan view of the chair according to the present invention. Fig. 7 is a perspective view of the chair according to the present invention. DETAILED DESCRIPTION OF THE INVENTION Referring now to Fig. 1, a first embodiment of a chair according to the present invention is shown. There are three major portions of the chair: a frame 10, a seat portion 20, and a back portion 30. The back portion is curved to adapt to a user's back and is composed of a front section 32 and a rear section 34, each of which has a lip 33, 35 or other spacer which creates a hollow interior space between sections when they are attached. The frame 10 is ideally a continuous structure, constructed of solid rod or tubular steel or the like. Alternatively, it may consist of welded or otherwise connected sections. The frame 10 has an upper curved section 12 which is enclosed within the back portion 30 with cylindrical bearing sections 12a at either end and which extends through the middle of the back portion and is angled downward. The frame 10 then extends from each end of the upper curved section 12 outward from the hollow interior, the back portion 30 being pivotally attached thereto at the cylindrical sections 12a. This pivotal attachment can be accomplished by bearings attached to the front section 32, but is preferably accomplished by providing bearing surfaces 12b formed on plastic molded front and back sections 32 and 34. The frame 10 has a pair of rear support legs 16 which extend downward and rearward to a floor surface and forwardly along the floor. A pair of front support legs 18 then extend upward and rearward to the front of the seat portion 20, then rearward supporting the seat portion 20, then slightly inward, then upward into the back portion 30, then inward, where the back portion is again pivotally attached in a manner similar to the pivot connection 12a and 12b. The frame 10 continues to a lower curved section 14 which is enclosed within the back portion and which extends through the back portion having a downward angle. The distance d χ between the opposing legs of the frame 10 as it sits on the floor is lesser than the width d 2 of the seat portion 20, so as to facilitate stacking a plurality of such chairs. In the preferred embodiment of Fig. 2, the seat supporting portion of the frame 10 is positioned inwardly from the edges of the seat portion 20 and connected by welded struts 22 to improve the support of the seat portion and lateral stability of the frame. In Fig. 7, such lateral stability can be provided by a pair of stabilizers 50, 52. Additionally, clips 24 are attached to the bottom surface of the seat portion 20 in order to easily attach/detach the seat portion to frame 10. The back portion 30 is a one-piece molded unit, having openings or clips 40 which are adapted to pivotally engage the rear support legs 16 at cylindrical sections 12a. Openings or clips 42 are likewise adapted to pivotally engage the front support legs 18. In this way, the back portion 30 may be easily and securely fitted to frame 10. The curved sections 12 and 14 remain in a fixed position relative to frame 10 to provide pivotal limits, as will be next described. Referring now to Figs. 3-5, the tilting action of the back portion 30 is illustrated. When the chair is in its upright position, as in Fig. 3, the rear support legs 16 of the frame 10 are inclined at a forward angle so as to provide a natural spring- type action which holds the back portion 30 forward. The curved sections 12 and 14 of frame 10 are parallel, each extending outward and downward from the back of the front section 32 at a twenty-two and one-half degree angle. The radii of curvature for both curved sections 12 and 14 is lesser than that of the back portion. But, the radius of curvature of section 12 projected at a plane inclined to the plane of section 12 by an angle of 22.5 degrees equals the radius of curvature of the back portion 30, such that the inside of the front section 32 is in contact with the curved sections 12 and 14 at points 36 and 37 as a result of the effective radius of the curved sections 12 and 14 being equal to the radius of the back portion 30. As a user leans back on the chair, the front section 32 pivots about point 50 on the upper curved section, causing the upper half of the front section to rotate backwards, and the lower half to rotate forward about point 50. Note also that the seat portion 20 will be lifted by the forward rotation of the lower curved section 14. Since the back portion 30 has a greater radius of curvature than both curved sections, the back portion lifts away from the curved sections as it is tilted, reengaging the curved sections at points 38 and 39, located further down the back portion, where the effective radii of the back portion is again equal to the radii of the curved sections after the back portion has tilted 45 degrees. A clearer view of the relationship of the curved sections 12 and 14 to the overall frame structure 10 is illustrated in Fig. 6 where the cylindrical sections of the frame 12a are apparent providing straight bearing areas. It should be understood that the invention is not intended to be limited by the specifics of the above-described embodiment, but rather defined by the accompanying claims.

Claims: I claim: 1. A high density stacking flex chair, comprising: a. a seat portion having a shape adapted to engage a user's seat; b. a back portion generally perpendicular to said seat portion and adapted to engage a user's back and having upper, intermediate, and lower regions; c. a frame for holding and supporting said seat and back portions, said frame comprising: i. a pair of rear support legs each pivotally connected to the intermediate region of said back portion and extending downward to a floor surface with said rear support legs spaced apart more than the width of the seat portion; and ii. a pair of front support legs each pivotally connected to the lower region of said back portion and extending forward to support said seat portion and downward to said floor surface, whereby the weight of the user urges the back portion to pivot with respect to the frame toward an erect position and pressure of the user's back against the upper region of the back portion can pivot the back portion toward a tilted position. 2. The chair of claim 1, wherein said back portion is curved to conform to a user's back. 3. The chair of claim 2, wherein said back portion comprises a front and rear section which are attached together, such that the attachment of said front and rear support legs to said back portion is enclosed within said front and rear sections of said back portion. 4. The chair of claim 3, wherein at the point of attachment of said rear support legs to said back portion, said rear support legs turn inward to face each other, and wherein at the point of attachment of said front support legs to said back portion, said front support legs turn inward to face each other, and wherein said frame further comprises: a. a first curvilinear section attached to each of said rear support legs at said back portion and extending across the intermediate region of said back portion at a downward angle, wherein said first curvilinear section has a radius of curvature less than that of said back portion, and wherein said back portion is pivotally attached to said rear support legs and first curvilinear section; b. a second curvilinear section attached to each of said front support legs at said back portion and extending across the lower region of said back portion at a downward angle, wherein said second curvilinear section has a radius of curvature less than that of said back portion. 5. The chair of claim 4, wherein said front and rear sections of said back portion form a hollow interior space such that said first and second curvilinear sections have limited clearance within said space to allow said back portion to be tilted about said first curvilinear section, such that when a user leans back, thus exerting rearward pressure on the back portion, said back portion will tilt at a rearward angle about said first curvilinear section, such tilting causing said seat portion to raise up in response to the pulling action exerted on said section curvilinear section. 6. The chair of claim 5, wherein said first and second curvilinear sections are positioned at a downward angle parallel to each other and whereby the curvilinear sections provide the pivotal limits for forward and backward tilting of the back portion, such that said front section of said back portion abuts and is stopped by said curvilinear sections when said back portion is in an upright position, and whereby the tilting of said back portion causes the interior of the back portion to move away from said curvilinear sections in a radial fashion, reengaging said curvilinear sections at an angle determined by the relative radius of curvatures between said back portion and said curvilinear sections. 7. A high density stacking flex chair, comprising: a. a seat portion adapted to engage a user's seat; b. a back portion generally perpendicular to said seat portion and adapted to engage a user's back and having upper, intermediate, and lower regions; c. a frame for holding and supporting said seat and back portions, said frame comprising: i. a pair of support legs which are pivotally connected to the intermediate region of said back portion and extending downward to a floor surface, forward along the floor surface, upward to the front of said seat portion, rearward to support said seat portion, and upward to attach to the lower region of said back portion at a location below the attachment of the legs to the intermediate region of said back portion, said legs diverging outwardly with respect to the floor surface with the legs spaced apart by more than the width of the seat portion in order to facilitate stacking; ii. a first curvilinear section attached to each of said support legs at the intermediate region of said back portion and extending across the intermediate region at a downward angle, wherein said first curvilinear section has a radius of curvature less than that of said back portion, and wherein said back portion is pivotally attached to said support legs and first curvilinear section; iii. a second curvilinear section attached to each of said support legs at the lower region of said back portion and extending across the lower region at said downward angle, wherein said second curvilinear section has a radius of curvature less than that of said back portion. 8. The chair of claim 7, wherein said back portion comprises a front and rear section which are attached together, such that the attachment of said support legs to said back portion is enclosed within said front and rear sections of said back portion. 9. The chair of claim 7, wherein said downward angle is equal to twenty-two and one-half degrees. 10. The chair of claim 7, further comprising a plurality of stabilizing supports, each connected at right angles between said pair of support legs. 11. The chair of claim 10, wherein a first stabilizing support member is located between said pair of support legs in the rear portion of the frame at the height of the seat portion, and a second stabilizing support member is located between said pair of support legs in the front portion of the frame at a height halfway between the floor surface and the seat portion. 12. A seat back adapted to engage a user's back for use in a chair which flexes or tilts when a user leans back in said chair, and support means which are adapted to engage said seat back, comprising: a. a curved seat back portion; b. curvilinear means forming part of said support means and having a radius of curvature less than that of said seat back portion; c. mounting means for pivotally attaching the seat back portion to said support means, with interference between the curved seat back portion and the curvilinear means providing the pivotal limits in both directions for tilting of the seat back portion. 13. The seat back of claim 12, wherein the tilting of said seat back causes the interior of the seat back portion to move away from said curvilinear means in a radial fashion, reengaging said curvilinear means at an angle determined by the relative radii of curvatures b etween said seat bade p ortion _ n _ saifl curvilinear means.

Inventors: PERRY CHARLES O, PERRY, CHARLES, O.
Applicants: PERRY CHARLES O, PERRY, CHARLES, O.
Application year: 1991
Main classification: A47C1
IPC codes: A47C1, A47C3, A47C7