Abstract:
A swivel arm adjustment device is provided for pivoting the armrest of a chair in order to allow multi-position adjustment to relieve stresses normally exerted on hands and wrists from improper hand positioning when typing. The swivel arm adjustment device includes a top member and a base member. The top member has a unitized construction and includes a centralized aperture, a first arcuate slot with resistance grooves and a second arcuate slot. The base member also has a unitized construction and includes a bushing with a snap-lock ring and a detent pin. The base and top members are adapted to be snapped together to form a pivotal coupling. The swivel arm adjustment device pivotally connects the armrest to the arm of a chair to provide a pivotal arrangement.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention may be described as an improved armrest swivel adjustment which is attached to the arms of an office chair and provides for multi-position rotational adjustment and is designed to be assembled without the need for additional fastening hardware, significantly reducing the time and cost required for manufacture and assembly.  
         DESCRIPTION OF RELATED ART  
         [0002]    Office chairs are equipped with an array of adjustments designed to allow an occupant to manipulate the chair into a position that allows them to work comfortably. With more computers in the workplace, employees are spending increased amounts of time seated in front of computer terminals which can lead to back pain and other ailments. Modern office chairs are ergonomically designed to allow the user of the chair to make adjustments to relieve stress and fatigue. Also, improper hand position when typing causes undue stress on wrists which can lead to carpel tunnel syndrome. To alleviate the stress on hands and wrists, chair armrests are adjustable to allow optimum positioning of the hands and wrists in relation to the keyboard. Adjustments may include height adjustment, lumbar support adjustment, back angle and height adjustment, lateral arm adjustment, vertical arm adjustment, forward and reverse armrest adjustment and swivel armrest adjustment. By allowing the armrests to pivot, the hands can be properly positioned in relation to the keyboard. Typical swivel armrest adjustments are comprised of many intricate pieces that take time to connect together during the assembly of the chair and usually require the use of tools. The additional time, hardware and manpower required to assemble the armrest swivel increases the overall cost of the product. Prior art devices that incorporate bolts to fasten the rotating armrest assembly together eventually loosen causing the armrest to improperly function. The prior art devices do not provide for a multiple position armrest assembly wherein the assembly is comprised of two pieces and can be snapped together without the use of tools.  
         SUMMARY OF THE INVENTION  
         [0003]    This invention may be described as an office chair arm swivel adjustment device that allows an armrest to be pivoted to a number of predetermined positions. The swivel armrest adjustment device is comprised of two sections, a base member and an attached top member. The base member includes a snap-lock bushing with an integral snap ring that connects with a central aperture on the top member. The snap-lock bushing design allows the top member and the base member to be snapped together eliminating the need for screws and other fasteners. Since the two members can be snapped together, assembly during manufacturing can be automated, reducing production costs. The base member further includes a detent pin that, upon assembly, is positioned in an arcuate slot located on the top member. The arcuate slot contains resistance grooves to provide multiple adjustment positions. When the detent pin is moved from one position to the next, the arcuate slot is deformed in shape by protruding into an adjacent secondary arcuate slot, also located on the top member, allowing the arcuate slot to expand far enough to allow for the passage of the detent pin into the next resistance groove. The swivel adjustment device allows a user to incrementally pivot the chair armrest clockwise or counterclockwise up to 30 degrees to allow for the proper positioning of the users arms and hands in relation to the work station and the chair seat. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]    [0004]FIG. 1 is an exploded view of the swivel arm adjustment device of the present invention.  
         [0005]    [0005]FIG. 2 is a perspective view of the upper surface of the top member of the swivel arm adjustment device.  
         [0006]    [0006]FIG. 3 is a perspective view of the lower surface of the top member of the swivel arm adjustment device.  
         [0007]    [0007]FIG. 4 is a perspective view of the upper surface of the base member of the swivel arm adjustment device.  
         [0008]    [0008]FIG. 5 is a perspective view of the base member of the swivel arm adjustment device. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0009]    While the present invention will be described fully hereinafter with reference to the accompanying drawings, in which a particular embodiment is shown, it is understood at the outset that persons skilled in the art may modify the invention herein described while still achieving the desired result of this invention. Accordingly, the description which follows is to be understood as a broad informative disclosure directed to persons skilled in the appropriate arts and not as limitations of the present invention.  
         [0010]    A preferred embodiment of a swivel arm adjustment  10  of the present invention is shown in FIG. 1 attached to a chair  12 . The swivel arm adjustment  10  is adapted to be fastened to a sleeve  14  which covers an arm  15  of the chair  12  such as an office or other style of chair, and to an armrest  16 . The swivel arm adjustment device  10  allows the user to pivot the armrest  16  in various positions to increase comfort and reduce fatigue.  
         [0011]    The swivel arm adjustment  10  is rectangular in shape and includes a top member  18  and a base member  20 . The top member  18 , as shown in FIGS. 2 and 3, includes a centralized aperture  22  a first arcuate slot  24  and a second arcuate slot  28 . The top member  18  is a generally planar with a top surface  30 , best shown in FIG. 2, and a spaced apart bottom surface  32 , best shown in FIG. 3. The top surface  30  has a recessed center portion  34  and two raised end portions  36  and  37 . The top surface  30  also includes two apertures  39  and  41  to allow access to the hardware on the base member  20 . The two raised end portions  36  and  37  come in contact with and support the armrest  16  upon assembly. The recessed center portion  34  houses the centralized aperture  22  and the first and second arcuate slots  24  and  28 . The recessed center portion  34  is reinforced by a rib  38  that extends from the centralized aperture  22  to end portions  36 . The raised end portions  36  and  37 , shown in FIG. 1, are planar and include apertures  40  and  42  to allow for the passage of fasteners  44  used to fasten the armrest  16  to the swivel arm adjustment  10 .  
         [0012]    The centralized aperture  22 , as shown in FIG. 2, is ringlike in shape and extends upwardly from the recessed center portion  34 . The top edge  46  of the aperture  22  is at an elevation slightly higher than the raised end portions  36  and  37 . Outer circumference  48  is in contact with inside surface  50  of side walls  52  of the recessed center portion  34 . The outer circumference  48  is also in contact with outside surface  54  of the first arcuate slot  24 , opposite the resistance grooves  26 . Inner surface  56  of the centralized aperture has a flat surface that acts as a bushing housing when the swivel arm adjustment system  10  is assembled. The inner surface  56  further includes an annular ridge  58  located near the bottom edge  60  which acts as a retaining ring to prevent detachment once the base member  20  is installed.  
         [0013]    The wall surrounding the first arcuate slot  24 , shown best in FIG. 2, is elevated above the recessed center portion  34  and includes a first side  64  and a second side  66 . An inside surface  62  of the first side  64  is smooth to allow a detent pin  68  formed on the base member  20  to slide along the surface without resistance. The second side  66  of the inside surface  62  contains five resistance grooves  26  placed along the entire length of the side  66 . The number of resistance grooves  26  can be varied depending on the number of adjustment positions desired. The resistance grooves  26  are arranged so that one of the grooves  26  has its centerline positioned midway along the length of the first arcuate slot  24 . The four remaining resistance grooves  26  are paired on both sides of the center groove  26  creating a center detent position, two right detent positions and two left detent positions. The outer two resistance grooves  26  define edges  72  of the slot  24  preventing any further movement. The detent pin  68  is sized so that when it is inserted into the first arcuate slot  24  the outer circumference  70  is in contact with the inside surface  62  of the first side  64  and one of the resistance grooves  26 , resisting any movement. Adjacent to the first arcuate slot  24  is a second arcuate slot  28  which is created by an absence of material on the bottom surface  32 . The second arcuate slot  28  follows the curve of the outside surface  54  and wraps around the edges  72 . The purpose of the second slot  28  is to provide space to allow for the encroachment of the second side  66  of the first arcuate slot  24 . The outside surface  54  of the second side  66  is uninhibited by any structure allowing the second side  66  to bow outward when enough force is exerted by the detent pin  68 , allowing the pin  68  to proceed to the next resistence groove  26 . The pin  68  is moved by applying enough rotational force to the top member  18  causing it to move.  
         [0014]    The bottom surface  32 , as shown in FIG. 3, is generally planar with the exception of two depressions  74  located at the extremities of the surface  32 . The bottom surfaces  76  of the depressions  74  house the apertures  40  and  42 , visible from the top surface  30 . The depressions  74 , shown best in FIG. 3, are designed to receive the head of a screw or other fastener  44 , shown in FIG. 1 as a bolt, to be recessed below the surface  32 . The ability to recess the fasteners  44  is important to allow the center section  82  of the bottom surface  32  to pivot in relation to the base member  20 . The center section  82 , shown in FIG. 3, also includes the centralized aperture  22 , the first arcuate slot  24  with resistance grooves  26  and the second arcuate slot  28 . The centralized aperture  22 , the first arcuate slot  24  with resistance grooves  26  and the second arcuate slot  28  are flush with a center section  82  of the bottom surface  32 . The top member  18  is designed so that the entire structure can be made out of a single piece of material. While it is preferable to form the entire top member  18  out of injected molded plastic, it is also possible to construct the member  18  out of metals, resins or other materials. To aid in the pivot action of the top member  18 , a plastic containing a self-lubricating additive such as graphite may be used.  
         [0015]    The base member  20 , of the swivel arm adjustment  10 , as shown in FIGS. 4 and 5, includes a top surface  84  and a spaced apart bottom surface  86 . The base member further includes four edges  87 ,  88 ,  89 ,  90 . The top surface  84  is generally planar and includes a central bushing  92  and detent pin  68  which extend from the surface  84 . The top surface  84  further includes two apertures  94  and  95  and two notches  96 . The central bushing  92  is circular in shape and has an inner surface  98  and an outer surface  100 . The outer surface  100  includes an integrated annular snap-ring  102  located near the top edge  104  of the central bushing  92 . The snap-ring  102  incorporates a beveled upper edge  106  designed to allow the bushing  92  to be pressed into the aperture  22  on the top member  18 , snapping them together. The lower edge  108  forms a ledge, preventing disassembly by interlocking with the top surface  59  of the annular ridge  58 . When the bushing  92  is pressed into the centralized aperture  22  the pressure exerted by the snap-ring  102  against the annular ridge  58  causes the walls  91  of the bushing  92  to constrict and the walls of the aperture  22  to expand, allowing the snap-ring  102  to pass by the annular ridge  58  and expand outwardly locking the two members together. The diameter of the snap-ring  102  is sized so that it is in contact with inner surface  56  of the aperture  22 . While the fit between the aperture  22  and the bushing  92  involves surface contact, it is noted that the two elements are sized to allow pivotal rotation of the top member  18  with respect to the base member  20 . The detent pin  68  is cylindrical in shape and affixed to the top surface  84  along the center line of the length of the base member  20 . The detent pin  68  has been positioned so that when the base member  20  and the top member  18  are aligned and pressed together, the detent pin  68  slides into the center resistance groove  26  of the first arcuate slot  24 . The apertures  94  and  95  are oriented in a staggered configuration, diagonal from the other. The apertures  94  and  95  further include a stepped bore  110 , shown best in FIG. 4, to allow the head of a fastener  112 , shown in FIG. 1, to be recessed below the top surface  84 . Apertures  94  and  95  allow the use of fasteners  112  to attach the swivel arm adjustment  10  to the sleeve  14  of the chair  12 . The top surface  84  of the base member  20  is in slidable contact with the bottom surface  32  of the top member  18  upon assembly. The notches  96  on the base member  20  are placed at opposing ends along edges  87  and  89 . The notches  96  are designed to allow the fasteners  44  to be removed and installed from the armrest  16 , shown in FIG. 1, when the chair  12  is either assembled or disassembled. The bottom surface  86 , as shown in FIG. 5, includes a plurality of ribs  114  in order to add flexural strength to the base member  20 . The base member  20  along with the central bushing  92  and detent pin  68 , in the preferred embodiment, are formed in a unitized fashion out of a single piece of material. While it is preferred to form the base member  20  from plastic, other materials such as metal or resin can be used, as well as various methods of manufacture such as injection molding and casting. Also, lubricants can be added to the plastic or metal to aid in the pivotal movement of the swivel arm adjustment  10 .  
         [0016]    During the assembly of office chair  12 , shown in FIG. 1, at the factory incorporating the swivel arm adjustment  10 , the top member  18  is attached to the armrest  16  by inserting the top surface  30  into the inside hollow of the armrest  16  and fastening the top member  18  and the armrest  16  together with screws  44 . Similarly, the bottom member  20  is placed upon the top of the sleeve  14  and fastened to the sleeve  14  with the use of screws  112 . Once the members are properly fastened, the aperture  22  of the top member  18  and the bushing  92  of the base member  20  are aligned and a force is exerted to snap the two members together. Once attached, a pivotal connection is formed and cannot be easily disassembled. The swivel arm adjustment  10  allows the armrest  16  of a chair to pivot either clockwise or counterclockwise through a predetermined number of positions without the use of tools, reducing the time required for assembly.  
         [0017]    Various features of the invention have been particularly shown and described in connection with the illustrated embodiment of the invention, however, it must be understood that these particular arrangements merely illustrate, and that the invention is to be given its fullest interpretation within the terms of the appended claims.