Abstract:
A method for manufacturing a chair assembly ( 20 ) with a customized backrest ( 46 ) includes fabricating a standardized frame ( 22 ), preparing a contoured plywood blank ( 48 ) for the backrest ( 46 ), selecting a customized design for the backrest ( 46 ) and then converting the design for the backrest ( 46 ) into a readable format, loading the readable format for the backrest ( 46 ) design into a customized cutting apparatus, loading the blank ( 48 ) into the cutting apparatus, cutting the blank ( 48 ) in conformity with the selected backrest ( 46 ) design, removing the completed blank ( 48 ) from the cutting apparatus, mounting the backrest ( 46 ) onto the frame ( 22 ), and lastly, mounting a seat ( 36 ) onto the frame ( 22 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 60/933,809 filed Jun. 8, 2007. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to the manufacturing of chairs, and more particularly to a method for efficiently manufacturing chairs having customizable backs. 
         [0004]    2. Related Art 
         [0005]    The introduction of chairs into Western Civilization is a relatively recent event as compared to the overall history of the Western world. Eastern cultures have only embraced chairs as a commonly used piece of furniture in recent decades by comparison. Indeed, there are still nomadic and rain forest cultures, among others, that do not employ chairs as we known them. In any event, the usefulness of the simple chair is often overlooked since it is so commonplace now and little thought is normally given to its origins or design. 
         [0006]    Perhaps one reason why chairs arise later in the history of human culture may lie in the complexity involved in chair design. Again, this complexity is not often realized since chairs and chairs of many different design types are ubiquitous in modern societies. However, when one considers the loading and function of a chair, the design attributes are revealed. When a person sits in a chair, a load is distributed through the seat and back portions into the frame of the chair where it is eventually transmitted to the floor upon which the chair (and now the occupant) sits. This relationship between the components of a chair system is a dynamic environment that requires a solid understanding of the parametrics of chair design. Failure to observe these parameters is likely to result in wasted efforts and materials, as the chair manufacture will be producing furniture that will routinely fail when used. 
         [0007]    As may be appreciated, early chair designs relied upon wood components and since these could be found in abundance, chair designs were generally robust and resulted from trial and error approaches. As modern construction materials became available, however, the use of steel, aluminum, stainless steel, and other alloys provided for greater strength in lighter frames of lesser overall substance. The upsurge in this type of chair design hit a stride in the 1950s with the increasing popularity of metal office and commercial furniture products. In these years, however, even the frames tended to be the result of overkill and were many times made so bulky or weighty that they were not well received by all potential users. 
         [0008]    Modern chairs have the advantage of proven frame designs that utilize minimized and refined frames compared to the early types of metal based chairs. This has made the frame based chair design very popular for industrial, commercial and residential applications. Such frame chairs are usually found with complementary seat and back portions that may be made from wood, plastic or metal, and which may be finished or which may be upholstered with fabrics and the like. This frame chair is the predominant type of chair especially in industrial and commercial uses, and versions of the frame chair have merged well with residential uses as well. Since the frame for the chair can be reproduced using mass manufacturing techniques, large numbers of chairs can be produced at very reasonable cost. The downside, however, is that the variability in the final cosmetic appearance of the frame chair is limited as a result of this prior art manufacturing methodology leading to a product that is typically offered in one configuration with perhaps a number of different finishes and/or colors. This limitation will many times reduce the desirability of the frame chair where people are looking to purchase seating for their restaurants, offices, schools, or other applications and want to match an existing or proposed decor or where the desire is merely to have something distinguished from the catalog of mass manufactured options. 
         [0009]    In U.S. Pat. No. 5,227,476 (Caldwell), a modular chair design is shown where the seat and back portions of the chair are independently associated with the “frame” of the chair and are easily assembled by the user. This modular chair design is predicated upon a substantial frame, preferably fabricated from wood components, and does not suggest a modular chair approach where customization of back and seat portions can be accomplished in the context of a mass production environment. Similarly, in U.S. Pat. No. 5,795,028 (Dussia, Jr. et al) an easy chair design is shown as being built up from a sub-frame, however this design is reliant on substantial componentry and does not teach a way to customize a frame chair in a mass manufacturing context. 
         [0010]    U.S. Pat. No. 3,870,366 (Rogers) discloses a knock-down modular type of chair based on wood components. All of the components, including the frame, the seat and the back, are independent and are assembled as a kit. This reference does not teach a frame chair of a modular design type that can be fitted with an unlimited number of customized back and/or seat portions. 
         [0011]    Furthermore, it is known in the chair making art to provide customers with a limited ability to customize certain aspects of a chair. For example, chair finish can be made to customer order, as well as various engraving or upholstering finishes. These prior art techniques are fairly limited, however, such that a designer has not the freedom to create interesting new shapes and chair profiles. 
         [0012]    There exists therefore a longstanding need in the chair making industry, where a chair assembly can be more fully customized to a designer&#39;s intent without diminishing structural integrity or unduly affecting production speed. 
       SUMMARY OF THE INVENTION 
       [0013]    A novel chair assembly is comprised of a frame for the retention of a backrest and a chair seat, where the backrest conforms to a select modular parameter and can be fitted onto the frame irrespective of the design treatment that is imparted to the backrest. The chair seat is similarly conformable to a select modular parameter and can be fitted onto the frame irrespective of the design treatment that is imparted to the chair seat. 
         [0014]    Another version of the present invention comprises a method for manufacturing a frame chair with a customized backrest. The method includes the steps of standardizing a frame for a chair assembly, fabricating the frame for the chair, preparing a blank for the backrest within select parameters, selecting a customized design for the backrest, converting the design for the backrest into a readable format, loading the readable format for the chair design into a customized cutting apparatus, loading the blank into the cutting apparatus, cutting the blank in conformity with the selected and loaded backrest design, removing the completed blank from the cutting apparatus, mounting the backrest onto the frame, and lastly, mounting a seat onto the frame. 
         [0015]    In a further version of the present embodiment includes the steps for customizing a chair seat. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein: 
           [0017]      FIG. 1  is a front elevation view of a chair assembly according to the subject invention showing the backrest with an initial profile in phantom and a customized profile in solid; 
           [0018]      FIG. 2  is a right side view of the chair assembly shown in  FIG. 1 ; 
           [0019]      FIG. 3  is a top view of the chair assembly shown in  FIG. 1 ; 
           [0020]      FIG. 4  is a perspective view of a backrest blank showing an initial profile; 
           [0021]      FIG. 5  is a cross-sectional view taken generally along lines  5 - 5  in  FIG. 4 ; 
           [0022]      FIG. 6  is a cross-sectional view taken generally along lines  6 - 6  in  FIG. 4 ; 
           [0023]      FIGS. 7A-F  depict a sequence of manufacturing steps, wherein a backrest blank is transformed into a finished backrest according to the subject invention; 
           [0024]      FIG. 8  is a front view of a backrest blank having an initial profile and showing certain dimensional parameters and the mounting surfaces in shade; 
           [0025]      FIG. 9  is one example of a completed backrest showing the backrest profile altered from the initial profile but yet the mounting surfaces in shade remaining unaltered. 
           [0026]      FIG. 10  is an other example of a completed backrest showing the backrest profile altered from the initial profile but yet the mounting surfaces in shade remaining unaltered 
           [0027]      FIG. 11  is a fragmentary view of a rear leg of the chair frame showing the mounting tab exploded away; 
           [0028]      FIG. 12  is a fragmentary view of a rear leg of the chair frame showing the a portion of the backrest fastened to the mounting tab with exemplary mounting screws; 
           [0029]      FIG. 13  is an exemplary collection of backrest designs that can be fabricated for a chair assembly according to this invention, wherein the backrest contour is unaltered from that of the blank and the mounting surfaces likewise remaining unaltered; and 
           [0030]      FIG. 14  is another exemplary view showing three side-by-side chair assemblies according to the subject invention, each chair assembly having a unique backrest profile that comprises a partial design theme, and wherein the design theme is completed when the chairs are arranged in a group of three. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]    Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a chair assembly according to the subject invention is generally shown at  20 . The chair assembly  20  has a rigid frame, generally indicated at  22 , including at least two front legs  24  and two rear legs  26 . Each rear leg  26  has an upper end  28 . Preferably, the rear legs  26  are longer than the front legs  24 , such that when set upright on a level surface, the upper ends  28  of the rear legs  26  are elevated above the front legs  24 . The legs  24 ,  26  are made of tubular metal in the preferred embodiment of this invention. Although it will be appreciated that the legs  24 ,  26  can be made from other materials like wood or plastic, and do not need to maintain a round cross-section nor a consistent dimensional quality along their entire lengths. 
         [0032]    The front legs  24  are attached to one another with at least on front stretcher  30 . The rear legs  26  can also be joined directly to one another with one or more rear stretchers, but in the preferred embodiment no rear stretcher is used for reasons to be described subsequently. Each rear leg  26  is directly connected to one respective front leg  24  with at least one chair rail  32 . Thus, two or more chair rails  32  extend between the front  24  and rear  26  legs to hold the leg  24 ,  26  in a generally vertical orientation and arranged in a generally square or trapezoidal configuration. A pair of transverse seat supports  34  extends between the chair rails  32 , and may be slightly curved as shown in  FIG. 12  to accommodate a complimentary contoured seat  36 . A seat  36  is shown in the fully assembled chair examples of  FIG. 14 . In  FIGS. 1-3 , the seat  36  is omitted from the chair assembly  20  for clarity. 
         [0033]    A mounting tab  38  is affixed to each rear leg  26  adjacent the upper end  28  thereof. The mounting tabs  38  are laterally spaced apart from one another a fixed distance. In the preferred embodiment, the mounting tabs  38  are plate-like members that are slightly skewed relative to the longitudinal extent of the respective rear legs  26 , such that the uppermost edges of the mounting tabs  38  are tilted toward the back. As perhaps best shown in  FIG. 11 , each mounting tab  38  has at least one, and preferably two, tennons  40  adapted to mate with complimentary mortises  42  in the respective rear leg  26 . The mounting tabs  38  can be secured in their respective mortises  42  on the rear legs  26  with a carefully applied weld (in the case of metal legs  24 ,  26 ), or glue or other bonding agent (in the case of wooden or plastic legs  24 ,  26 ). Each mounting tab  38  is machined to include two (or more) fastener holes  44 . 
         [0034]    The subject invention is directed particularly toward a method for manufacturing chair assemblies  20  having a backrest, generally indicated at  46 , with a profile that is easily configurable at the design inspiration of a customer. To accomplish this objective, the backrest  46  is formed from a chair back blank  48  having an initial profile, as illustrated in broken lines in  FIGS. 1-3  and in solid lines in  FIGS. 4-6 . The blank  48  has a generally uniform thickness and is generally rigid so as to maintain compound curved contours adapted to conform to the backside of a human torso. The compound curving design of the blank  48  is perhaps best shown in  FIGS. 4-6 . Preferably, the blank  48  is formed by laminating several thinly sliced wood sheets back-to-back while compressing them between opposing mold surfaces. Of course, non-plywood materials can be used with effectiveness, such as metal, masonite, high pressure laminates, and machinable acrylics, to name a few. The blank  48  has a dimensional height A and a dimensional width B as described in  FIG. 8 . The blank  48  has an initial profile, defined as the shape as viewed from the front like that in  FIGS. 1 ,  7 A and  8 . 
         [0035]    Two mounting surfaces  50  are established on the blank  48 , along its lowermost edge at the extreme outward sides. In  FIG. 8 , the mounting surfaces  50  are shown as shaded areas of generally rectangular shape corresponding in size to the mounting tabs  38 . Accordingly, the mounting surfaces  50  are laterally spaced apart from one another a distance X corresponding to the mounting tabs  38  on the rear legs  26 . In  FIG. 8 , the mounting surfaces  50  are depicted having a height Y. Two fastener holes  51  are milled in each mounting surface  50 . These holes  51  can be drilled, laser cut, punched or in some other manner created in the blank  48  to correspond with the fastener holes  44  in the mounting tabs  38 . Preferably, side extensions  52  are created above the mounting surfaces  50 , enabling the dimensional width B to be greater than the outside distance X between the mounting surfaces  50 . The outside distance X corresponds to the lateral spacing between the rear legs  26 , whereas the dimensional width B establishes a maximum width for the finished backrest  46 . 
         [0036]      FIGS. 9 and 10  represent two sample backrest  46  profiles altered from the initial profile of  FIG. 8 . These illustrations depict how the spacing between the mounting surfaces  50  remains unaltered during the profile reconfiguration process. 
         [0037]    Referring now to  FIGS. 7A-F , an exemplary manufacturing sequence for configuring a backrest  46  to customer order is shown. The sequence begins by providing the backrest blank  48  as described above. A customer request is received to manufacture a chair assembly  20  having a backrest  46  profile that is different than the initial profile. Based on the desired new profile requested by the customer, the backrest  48  profile is cut, such as by a computer controlled laser cutting device shown in  FIG. 7B , without altering its compound curved contours and without altering the lateral spacing between the mounting surfaces  50 . As an alternative to laser cutting, any known technique can be used to reconfigure the backrest  46  profile, including CNC routing, or water jet cutting to name a few. Fully inset, or included, holes and other shapes can also be imparted to the backrest  46  to achieve desired design or functional elements as illustrated in  FIG. 7C . As one example, an ergonomically shaped cutout can be milled near the top edge of the backrest  46  to serve as a handle. Other included shapes can likewise be cut into the backrest  46 . 
         [0038]      FIGS. 7D-7F  illustrate various optional and/or alternative steps of applying a surface treatment to the reshaped backrest  46 .  FIG. 7D , more specifically, shows a laser etching process, wherein a decorate picture, logo, word or other feature is burned into the surface of the backrest  46 . Although not shown, surface treatments can also include various forms of grooving and embossing, which can be accomplished using CNC routing or other suitable technique. A spraying process is depicted in  FIG. 7E , which can represent a painting or staining operation, clear coating operation, or other application of atomized coating material as a surface treatment to the reshaped backrest  46 . In  FIG. 7F , an upholstered pad  54  is shown as another form of surface treatment. The shape as well as the color of the resilient pad  54  can be designed by the customer to accomplish their particular design intention. 
         [0039]    Once the backrest  46  has been fully fabricated and configured to the customer&#39;s specification, it is fastened to the chair frame  22  by mechanically connecting the mounting surfaces  50  directly to respective mounting tabs  38  as shown in  FIG. 12 . While screws  56  are used as exemplary illustrations in  FIG. 12 , it will be appreciated that other fastening techniques know to those of skill in the art can be substituted for the screws  56 . The rigid nature of the backrest  46  provides structural support to the chair frame  22 , thus enabling the need for a rear leg stretcher in some applications. 
         [0040]    A novel method for manufacturing a frame chair  22 , and the resulting chair assembly  20 , are the subjects of the present invention. Chair frame designs of the prior art inherently limit the ability of chair manufacturers to easily fulfill custom requirements of the purchaser. With the present invention, however, it is possible for the purchaser to specify the type of backrest  46  design treatment he/she may desire, including cuts, embosses, and outer shapes. Virtually any design intent of the customer may be readily implemented. Examples of customized backrests  46  of the present invention are shown in  FIG. 13 , wherein discrete designs are identified with reference letters A-T. In each example, the backrest  46  profile is a reconfigured form of the initial profile, and the mounting surfaces  50  remain unaltered in terms of their relative spacing one from another so that they can be attached to the mounting tabs  38  in the manner described above. 
         [0041]      FIG. 14  shows the effect of combining related design treatments among juxtaposed chair assemblies  20 . In this example, each backrest  46  carries a related partial design theme which can be expressed as a whole only when the chairs  20  are arranged in a group of three (or two or more). 
         [0042]    Although not shown in any of the figures, those of skill in the art will recognize that a chair  20  of the present invention may be fitted with arm rests and possibly other features without detracting from the novel aspects described above. 
         [0043]    In use, the modular chair system of the present invention is reliant upon the dimensional envelope in which the backrest  46 , and to a lesser degree the chair seat  36 , may be allowed to exist. This envelope is comprised of the outer parameters A and B which define the maximal area which the backrest  46  can occupy. The dimensional envelope is also comprised of the mounting parameters, X and Y which define the area for a select configuration for the backrest, typically a lowermost portion of the blank  48 , with height Y which roughly corresponds to the height of each mounting tab  38  and with width X which roughly corresponds to the distance between the rear legs  26 . This dimensional envelope for the backrest  46  is the basis that allows for the liberality in selecting different design treatments. 
         [0044]    For the first time a customer will have the unfettered capability to design their own furniture (within the boundaries explained above) which encompasses an endless array of possibilities. For example, embossing can be accomplished using CNC routing on a selected wood substrate and can range from intricate carvings, logos and names, geometric patterns, and so on. 
         [0045]    As may be inferred for the foregoing discussion, the manufacturer of a chair  20  product of the present invention can utilize mass manufacturing techniques for the production of the frame  22 . The frames  22  can be easily standardized from which fixturing, jigs, tooling, and other manufacturing tools can be configured with the end result that the frame  22  can be made for nearly the same costs as frames for non-customized chair products. This renders a great advantage to the present invention which allows the chair products to be sold to a much larger market. 
         [0046]    The customization of the chair seat  36  can occur in the same manner as set forth above, although there are practical and cosmetic reason why this approach will likely be less utilized than the customization of the backrest  46 . Even if a standard chair seat  36  is settled upon for use in conjunction with the present invention, the standard chair seat  36  can be matched to meet the cosmetic selections, base material selections and the like, that are made by the customer. 
         [0047]    The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.