Patent Publication Number: US-7591511-B2

Title: Tamper resistant attachment device for a chair backrest

Description:
Benefit is claimed of U.S. Provisional Patent Application No. 60/749,778, filed Dec. 12, 2005, which is herein incorporated by reference in its entirety for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to chairs, and more particularly to affixing a backrest and seat to a chair frame. 
     2. Related Art 
     Typical chairs have a backrest and seat that are attached to a chair frame. Some backrests and seats are attached to the chair frame by stapling a cloth or fabric to a wood frame. Others are attached by riveting or screwing a backrest or seat frame to the chair frame. Most backrests or seats require some sort of fastener, such as rivets, screws, bolts, staples, or the like to attach the backrest or seat to the chair frame. However, these fasteners are problematic in that they increase the production time and cost for chairs. Moreover, use of separate fasteners to attach a backrest of seat to a chair frame can result in lost fasteners, both during the production of the chair and in after-production use since traditional fasteners can commonly work themselves loose. Additionally, many traditional types of fasteners are easily tampered with such that the fastener can be removed thereby loosening or removing the backrest or seat. 
     SUMMARY OF THE INVENTION 
     It has been recognized that it would be advantageous to develop a device and method for attaching a chair backrest and seat to a frame that uses a self fastening mechanism to eliminate separate fasteners. Additionally, it has been recognized that it would be advantageous to develop a device and method for attaching a chair backrest and seat to a frame that is not easily tampered with and reduces the possibility of a loose or missing backrest or seat. 
     The invention provides for a tamper resistant attachment apparatus for attaching a backrest to a chair frame. The apparatus can include a backrest supportable by a chair frame. A flap can be foldably coupled to an edge of the backrest. The flap can be foldable around the chair frame and onto the backrest in a folded position. A channel extends along the flap, and can be sized and shaped to fit around the chair frame when the flap is in the folded position. The flap has at least one aperture and receives a corresponding pin that is coupled to the backrest. The pin can be deformable and can secure the flap against the backrest with the chair frame enclosed in the channel when the flap is in the folded position and the pin is deformed. 
     In another aspect, the present invention provides for a chair with a tamper resistant backrest and seat attachment apparatus including a backrest that can be sized and shaped to fit in a back frame of the frame of the chair. A plurality of flaps can be pivotally or foldably coupled to a portion of a peripheral edge of the backrest. A plurality of pins can be coupled to the backrest or seat and can correspond in position to at least one aperture in each flap when the flaps are in a folded or closed position. Each pin can be deformable to secure the flap and backrest around the chair frame when the flap is in the closed position. 
     The present invention also provides for a method for attaching a backrest to a chair frame including placing a backrest on the chair frame. The backrest can have a plurality of foldable flaps that can be folded to enclose the chair frame in a channel formed in the flap, and an aperture on each of the plurality of flaps can fit over a corresponding pin that can protrude from the backrest. Each of the plurality of pins can be deformed to form a pin head that secures the flap around the chair frame and against the backrest. 
     Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a rear perspective view of a tamper resistant, fastenerless attachment apparatus for a chair backrest or seat in accordance with an embodiment of the present invention, shown in relation to a chair; 
         FIG. 2  is a perspective view of the attachment apparatus of  FIG. 1 , shown in an open configuration; 
         FIG. 3  is a perspective view of the attachment apparatus of  FIG. 1 , shown in a closed configuration; 
         FIG. 4  is a cross section view of the attachment apparatus of  FIG. 1 , shown in a closed configuration; 
         FIG. 5  is a perspective view of a chair having a plurality of tamper resistant, fastenerless backrest or seat attachment devices in accordance with an embodiment of the present invention; and 
         FIG. 6-8  illustrate a method for fastening a backrest or seat to a chair frame. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the exemplary embodiments illustrated in the drawings, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Alterations and further modifications of the inventive features illustrated herein, and additional applications of the principles of the inventions as illustrated herein, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the scope of the invention. 
     The present invention generally provides for an attachment apparatus to attach a backrest or seat to a chair frame. The attachment apparatus has a flap hinged to the backrest or seat. The flap can be folded over and onto the backrest or seat to a folded position. The flap has a channel that can enclose about the chair frame when the flap is in the folded position. The flap also has at least one hole or aperture. The hole fits over a pin that is coupled to the backrest or seat. The flap and the pin can be integrally formed with the backrest. When the flap is in the folded, the pin can protrude through the flap. The protruding portion of the pin can be deformed to secure the flap in the closed position, thereby retaining the chair frame in the channel. 
     In addition, the present invention provides a method for attaching a chair backrest or seat to a chair frame including positioning a backrest in a chair frame and folding a flap coupled to the backrest or seat over the frame. The flap can be secured to the backrest or seat with a pin coupled to the backrest. 
     As illustrated in  FIGS. 1-4 , an attachment apparatus, indicated generally at  10 , in accordance with the present invention is shown for use in attaching a backrest or seat to a chair frame, such as a wire chair frame, a tubular chair frame, or the like. It will be appreciated that the attachment apparatus of the present invention can be used to attach either a backrest or a seat, or both, to a chair frame. Accordingly, for purposes of this application, the terms “backrest” and “seat” are interchangeable and for convenience will hereafter be referred to as only as “backrest” with the understanding that while the description below refers to a chair “backrest”, the principles described could equally apply to a chair “seat”. 
     The attachment apparatus  10  has a flap  20  that is pivotably or foldably coupled to an edge  24  of a chair backrest  28 . The flap  20  can have an open position as shown in  FIG. 2 . The flap  20  can also have closed or folded position as shown in  FIG. 3 . In the folded position, the flap  20  can be pivoted or folded over and onto the backrest  28 . The flap  20  and the backrest  28  can be formed from a moldable plastic material. In one aspect, the flap  20  and the backrest  28  can be made from the same moldable plastic material, and, thus, the flap  20  can be integrally formed with the backrest  28 . 
     A bendable membrane  30  can couple or hinge the flap  20  to the backrest  28 . The bendable membrane  30  can act as a hinge that allows the flap  20  to pivot or fold over onto the backrest  28 . In the case where the flap  20  and backrest  28  are integrally formed, the bendable membrane  30  can also be integrally formed as a thinner region of the same moldable plastic material between the flap  20  and the backrest  28 . In another aspect, the bendable membrane  30  can form a living hinge between the backrest  28  and the flap  20 . 
     The flap  20  can also have a channel  32  that can extend along the flap  20 . The channel  32  can be sized and shaped to fit around, and enclose about, a frame  34  of a chair when the flap  20  is in the folded position. In the case where the chair frame  34  is a wire frame or tubular frame, the channel  32  can have a substantially cylindrical shape that corresponds to the cylindrical shape of the chair frame  34 . It will be appreciated that the shape of the channel  32  can correspond to other common chair frame shapes, as known in the art. 
     The flap  20  can also have at least one aperture  38 . In one aspect, the aperture  38  can be a hole that extends through the flap  20 . The aperture  38  can be formed in the flap  20  away from the channel  32  so that when the flap  20  is in the folded position, the chair frame  34  enclosed in the channel  32  will not interfere or close off the aperture  38 . 
     The at least one aperture  38  can receive and fit over at least one pin  42  coupled to the back rest or seat  28 . As shown in  FIGS. 1-3 , the flap  20  can have two apertures  38  and the backrest or seat  28  can have two pins  42  that correspond in position to the two apertures  38  when the flap  20  is in the folded position. The pins  42  can be sized and shaped to fit through the apertures  38 . 
     A portion  46  of the pins  42  can protrude out of the apertures  38  when the flap  20  is in the closed position. The pins  42  can be deformable so that the portion  46  that protrudes out of the apertures  38  can be deformed into a head  50  with a larger size than the aperture  38 . By creating a head  50  on the pins  42 , the pins can secure the flap  20  from opening and lock or clamp the flap  20  and backrest  28  around the chair frame  34 . The pins  42  can be deformed by applying heat to the pin  42 . Thus, in one aspect, the pins  42  can be heat stakes that are driven through the flap  20  and deformed by heat to stake the flap  20  into place on the backrest  28 . 
     The pins  42  can be formed of a moldable plastic and can be integrally formed with the backrest  28 . In this way, the attachment apparatus  10  can have no loose or separate parts, such as fasteners, but instead is formed as a single piece integrally formed with the backrest  28 . Advantageously, a single piece attachment apparatus decreases production time and costs since additional parts do not have to be added to the attachment apparatus. Additionally, the attachment apparatus of the present invention can reduce production costs over attachment devices that use fasteners because loose parts, such as fasteners, will not be lost or broken in the manufacturing process. 
     The at least one aperture  38  can have a polygonal shape or cross section, so that when the pin  42  is deformed to form the head  48 , portions of the pin can deform to a corresponding polygonal shape. The polygonal shape of the aperture provides several advantages to locking the flap  20  of the present invention. For example, the portions of the pin that deform to the polygonal shape can restrict motion of the pin  42 . It will be appreciated that, even slight motion of the pin could result in fatigue and ultimately in failure of the pin. 
     Additionally, the aperture  38  can be slightly smaller than the pin  42  creating an interference fit between the pin and the aperture. Advantageously, an interference fit strengthens the pin-aperture coupling. Furthermore, an aperture  38  with a polygonal shape is more easily deformable because of the flats of the polygon can bend in response to applied loads while the points of the polygon resist movement and act to substantially retain the basic cross sectional area of the polygon. Thus, when a slightly larger pin  42  is pressed through the aperture  38 , the points of the polygonally shaped aperture  38  resist deformation of the flats such that the pin is allowed to pass through the aperture  38 , but an interference fit is created between the pin  42  and the aperture  38 . 
     As illustrated in  FIG. 4 , in use, the backrest  28  can be positioned in a chair frame  34  and the flap  20  on the backrest  28  can be folded over the chair frame  34  to enclose the chair frame  34  in the channel  32 . The pins  42  on the backrest  28  can fit into the apertures  38  on the flap  20 , and a portion  46  of the pins  42  can protrude out of the apertures  38 . The pins  42  can be deformed to form a head  50  on the pin. The head  50  on the pin can secure the flap  20  from opening and releasing the chair frame  34 . Consequently, the flap  20  can clamp around the chair frame  34  and secure the backrest  28  to the chair frame  34 , and the pins  42  can lock the flap  20  to retain the flap  20  in the folded position. 
     Referring to  FIG. 5 , a chair, shown generally at  100 , is shown with a backrest  28  attached to a chair frame  34  with the tamper resistant attachment apparatus  10  described above in accordance with an embodiment of the present invention. The chair frame  34  includes a back frame  110  and a seat frame  120 . The chair also includes a backrest  28  that can be sized and shaped to fit in and be supported by the back frame  110 . 
     The backrest  28  can have a plurality of flaps  20  that are pivotally or foldably coupled to a peripheral edge  24  of the backrest  28 . Each flap  20  can be coupled to the backrest  28  by a bendable membrane  30  in order to allow each flap  20  to pivot or fold onto the backrest or seat  28  into a folded position. 
     As described above, each flap  20  can have a channel  32  that can extend along the flap  20 . The channel  32  can be sized and shaped to fit around the back frame  110  of the chair  100  when the flap  20  is in the folded position. The flap  20  can also have at least one aperture  38  formed in the flap  20 . The aperture  38  can be formed away from the channel  32  to prevent interference of the aperture  38  by the back frame  110 . 
     A plurality of pins  42  can be coupled to the backrest or seat  28 . Each pin  42  from the plurality of pins  42  can correspond in position to the at least one aperture  38  of each flap  20  when the flaps  20  are in the closed position. Each of the plurality of pins  42  can be sized and shaped to fit in the apertures  38 . Additionally, each pin  42  can be deformable to secure the flap  20  around the back frame  110  with the back frame  110  enclosed in the channel  32  when the flap  20  is in the folded position. 
     The back frame  110  can also have an upper curvilinear member  114  that can extend between two lateral posts  118 . The lateral posts  118  can extend downward from the curvilinear member  114  to the seat frame  120 . 
     A frame guide  130  can be formed in the backrest  28  and can be sized and shaped to fit around the back frame  110 . The frame guide  130  can position the backrest  28  on the back frame  110  and secure the backrest  28  from movement on the lateral posts  118  when the flaps  20  are locked in the folded position. Thus, the backrest  28  can be secured to the chair frame  34  by the flaps  20  and be restricted from movement along the chair frame  34  by the frame guides  130 . 
     As illustrated in  FIGS. 6-8 , the present invention also provides for a method for attaching a backrest  28  to a chair frame  34  including placing a backrest on the chair frame, as shown in  FIG. 6 . The backrest can have a plurality of flaps  20 . Each of the plurality of flaps can be folded to enclose the chair frame in a channel  32  formed in the flap, and an aperture  38  on each of the plurality of flaps can fit over a corresponding pin  42  that can protrude from the backrest, as shown in  FIG. 7 . A portion  46  of each of the plurality of pins can be deformed to form a pin head  50  that secures the flap around the chair frame and against the backrest, as shown in  FIG. 8 . Each of the plurality of pins can be deformed by heating the pins and applying a force to form a head on the pin. It will be appreciated the head on the pin can also be formed by mechanical force alone, as known in the art. 
     It will also be appreciated that while the embodiments described herein have a pin protruding from a backrest that fits into an aperture on a flap, the positions of the pin and aperture can be switched. Namely, the pin can be formed on, and extend away from the flap, and the aperture can be formed in the backrest. Thus, the pin on the flap can extend into the aperture on the backrest when the flap is folded over the chair frame. 
     It is to be understood that the above-referenced arrangements are only illustrative of the application for the principles of the present invention. Numerous modifications and alternative arrangements can be devised without departing from the spirit and scope of the present invention. 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 can be made without departing from the principles and concepts of the invention as set forth herein.