Abstract:
A tablet arm apparatus providing a re-positionable and stowable tablet work surface which is easily mounted on a chair or integrated into a chair design is described in which movement in each axis is independent and is accomplished by an articulating arm assembly or a single inexpensive two-axis hub.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a tablet arm for furniture, particularly a chair. More specifically, the invention concerns a work tablet that mounts to a chair and uses an assembly having two or more degrees of freedom to pivot and rotate the tablet from a vertical stowed position at the side of the chair to an deployed position above and parallel to the seat of the chair. 
     A number of chair tablet designs have a mechanism that support the work tablet in a first horizontal position over the chair seat and in a second stowed position when the tablet is not in use. However, few designs have provided an apparatus that can be integrated into the chair design and that allow repositioning of the tablet from above the chair seat to a position to the side of the chair by both rotating the tablet from the horizontal plane to the vertical plane or, when the tablet is in use, by merely swinging the tablet in the horizontal plane. Further, as an easily mountable accessory to a chair, none of the existing tablet designs provide rotation of the tablet from the horizontal plane to the vertical plane and independent rotation in the vertical plane to a stowed position along the side of the chair using a single inexpensive two-axis hub. 
     One design that provides a horizontal tablet position above a chair and repositions to a stowed vertical position at the side of the chair is Bauman et al., U.S. Pat. No. 5,683,136. The tablet must be pivoted from the horizontal to the vertical plane using one pivot joint then slid to a position along the side of the chair using a slide mechanism. This design does not allow repositioning of the tablet without rotating it from the horizontal plane, nor does it allow the tablet to be rotated within the horizontal plane. 
     Two designs that use angled pivot joints for positioning are Benoit, U.S. Pat. No. 4,216,994, and Phoon, U.S. Pat. No. 5,845,964. The angled pivot joints cause the tablet to be rotated through the horizontal and vertical planes simultaneously. Other designs, such as the patent to Sorenson, U.S. Pat. No. 5,765,911, allow motion in one plane independent of the other and movement of the tablet without upsetting its horizontal position. However, such designs require manual loosening and re-tightening of friction brakes before and after repositioning. 
     The alternative design of Kanigowski, U.S. Pat. No. 4,852,940, provides multiple axis motion using a single ball-joint, but fails to provide integral stops or locks. In order to maintain a horizontal position, the chair arms or a shelf extending from them must support the tablet. A design patent to Best, U.S. Pat. No. 409,860,illustrates a mountable accessory, requiring two mounting bars and two single-axis pivot joints to provide repositioning to a stowed position. 
     In light of the shortcomings of these prior devices, there remains a need for a tablet arm apparatus that allows the tablet to rotate to a vertical position or to move through the horizontal plane without upsetting the other plane of motion and without having to fully stow the tablet for a person to enter or exit of the seat of the chair while requiring only one mount and one inexpensive two-axis joint and furthermore, not requiring manual friction brakes to lock an axis of motion of the tablet. 
     SUMMARY OF THE INVENTION 
     Briefly describing one aspect of the invention, the work tablet arm apparatus includes a tablet plate for mounting a work tablet and an articulating arm assembly providing various tablet positions and configured for attachment of the apparatus to a chair. 
     The difficulties with prior chair tablet arm apparatuses are overcome in one aspect of the current invention by the articulating arm assembly. The arm assembly in one embodiment includes a pivot rod assembly connecting one end of a long arm to one end of a short arm. The other end of the long arm can be rotationally connected to the tablet plate using a slotted washer and stop pin combination that allows limited rotation of the tablet independent of the arm position. The other end of the short arm can be pivotably mounted to the chair arm, preferably as an integral element of the chair design. In one aspect of this embodiment, the short arm pivot provides a means for moving the tablet from a position over the seat of the chair to the front of or other side of the arm of the chair. This pivot allows a person to enter or exit the seat without having to fully stow the tablet and without upsetting the contents of the tablet. 
     In a further aspect, the pivot rod assembly provides a means for rotating the tablet and long arm about an axis parallel with the chair seat. The pivot rod assembly can include a bias spring for engaging a locking pin into a locking notch, stopping rotation of the long arm when the tablet is parallel to the chair seat. The long arm rotation about the pivot rod provides for quick movement of the tablet when it is not in use. When combined with a pivot to the outside of the arm of the chair, the long arm also provides for stowing the tablet in a vertical position along the outside of the arm of the chair. The chair tablet arm apparatus requires no manual friction brakes and no external support of the tablet other than a single mounting point. 
     In another embodiment of the invention a chair tablet arm apparatus is provided as an accessory to an existing chair design and is capable of two-axis motion using a single inexpensive hub and a single mounting bracket. The chair tablet arm apparatus in this embodiment can include a tablet plate, a pivot hub assembly, a mounting bar, and a mounting bracket. The mounting bracket can function to attach the apparatus to an existing member of the chair such as a chair leg. The mounting bar rotationally attaches the mounting sleeve to the pivot hub assembly. The pivot hub can be pivotably attached to the tablet plate. 
     The pivot hub assembly can include spring-biased pins that engage the mounting bar, and are operable to stop rotation of the hub around the mounting bar when the tablet is at a rotational position for pivoting. The tablet plate can then pivot between a position perpendicular to a position parallel to the chair seat. In the perpendicular position, the tablet can rotate independently within the perpendicular plane to a stowed position at the outside of the chair member to which the apparatus is attached. 
     One object of the invention is to provide a stowable tablet arm apparatus that can be readily integrated into an existing chair using a single mounting point. Another object is to such a tablet arm apparatus that can provide two-axis motion using a single inexpensive joint. 
     One benefit is that the tablet can be rotated to a vertical position or moved through the horizontal plane without upsetting the other plane of motion and without having to fully stow the tablet for a person to enter or exit the seat of the chair. Another benefit is that the apparatus requires no manual friction brakes to lock an axis of motion of the tablet. 
     These and other objects, advantages, and features are accomplished according to the devices, assemblies, and methods of the present invention. 
    
    
     DESCRIPTION OF THE FIGURES 
     FIG. 1 is a perspective view of a chair tablet arm apparatus according to one embodiment of the invention, utilizing a single pivot hub assembly and shown in a deployed position. 
     FIG. 2 is a front elevational view of the chair tablet arm apparatus depicted in FIG.  1 . 
     FIG. 3 is a top view of the chair tablet arm apparatus depicted in FIG.  1 . 
     FIG. 4 is a perspective view of the chair tablet arm apparatus of FIG. 1 mounted on a chair and in a deployed position. 
     FIG. 5 is a perspective view of the chair tablet arm apparatus depicted in FIG. 1 but shown in a stowed position. 
     FIG. 6 is a top perspective view of a chair tablet arm apparatus according to a further embodiment of the invention, utilizing an articulating arm assembly. 
     FIG. 7 is a front elevational view of the chair tablet arm apparatus shown in FIG. 6 but integrated into a chair design and shown in a stowed position at the outside of the chair arm. 
     FIG. 8 is a top plan view of a chair tablet arm apparatus shown in FIG. 6, but integrated into a chair design and shown in a deployed position at the outside of the chair arm and in a deployed position above the chair seat. 
     FIG. 9 is a perspective view of a chair tablet arm apparatus shown in FIG. 6 but integrated into a chair design and with the tablet in a deployed position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     For the purposes of promoting an understanding of the principles of 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. The invention includes any alterations and further modifications in the illustrated devices and described methods and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates. 
     The present invention relates to a tablet arm apparatus for furniture, particularly a chair. More specifically, the invention concerns a work tablet that mounts to a chair and uses an assembly having two or more degrees of freedom to pivot and rotate the tablet from a vertical stowed position at the side of the chair to a deployed position above and parallel to the seat of the chair. 
     In accordance with one embodiment of the present invention, a chair tablet arm apparatus  10  is shown in FIG.  1  and as attached to a chair in FIG.  4 . The apparatus  10  contemplates a tablet plate  11  pivotably attached to a pivot hub assembly  16 , which is itself rotationally attached to a mounting bar  20 . The apparatus  10  can be generally constructed of plastic or lightweight metal and can be attached to a member of a chair, such as a chair leg, with a mounting bracket  27  as depicted in FIG.  4 . The apparatus is movable from a deployed position  10 ″ (FIG. 4) above and parallel to the seat of the chair, and a vertical stowed position  10 ′ at the side of the chair as depicted in FIG.  5 . The stowed position  10 ′ facilitates easy access to or exit from the seat of the chair. The deployed position  10 ″ provides a work surface functional to a person seated in the chair. 
     Referring to FIGS. 1 and 2, the mounting bracket  27  in one specific embodiment preferably includes two opposing “C” clamp portions  28  and  29 . Each clamp portion  28  and  29  defines a curved portion  28   a  and  29   a  forming a half cylinder, and a flat flange  28   b  and  29   b  extending the length of one end of the cylinder. The flange  28   b  of clamp portion  28  is attached to a long arm  21  of the mounting bar  20 , preferably at three weld points  32 . The apparatus  10  can be mounted to a chair leg, as depicted in FIG. 4, by first positioning the clamp portion  28  with the half cylinder  28   a  in contact with one side of the chair leg. The second clamp portion  29  is then placed in juxtaposed mirror image fashion so that the two half cylinders  28   a  and  29   a  cooperate to enclose the chair leg. Three alignment dimples  31  defined between the two flanges  28   b  and  29   b  align the clamp portions and the portions are drawn together by a number of screws  33 . The screws  33  and dimples  31  cooperate to allow the clamp portions  28  and  29  to firmly grip the chair leg. The interior of the half cylinder portions  28   a  and  29   a  of each clamp  28  and  29  is preferably lined with foam tape  30  to provide a firm attachment to the chair member  34 . 
     The mounting bar  20  extends from a long arm  21  through a 90-degree bend  23  to a short arm  22 . The pivot hub assembly  16  can include a bearing hub  17 , a retaining nut  19 , a rest bracket  24 , and a washer  25 . The hub assembly  16  is rotationally mounted on the short arm  22  of the mounting bar  20 , with the end  22  passing through a central opening  18  (FIG. 3) of the hub  17 . The retaining nut  19 , which is preferably a cap nut, can be attached to the short arm  22  of the mounting bar to trap the hub  17  between the retaining nut  19  and the washer  25  and rest bracket  24 . The rest bracket  24  is preferably fixed to the short arm  22 , such as at weld points  26 . The washer  25  provides a sliding surface for the hub  17  relative to the rest bracket  24 . In the deployed position  10 ″ depicted in FIG. 2, the tablet plate  11  is supported by the rest bracket  24  in a generally horizontal attitude. 
     Referring to FIG. 1, the tablet plate  11  has a flat surface having multiple mounting holes  12  defined therethrough by which a solid work surface may be attached. The plate further includes a pair of mounting ears  13  forming a U-shape extend from one end thereof. The mounting ears  13  are spaced apart to receive the pivot hub  17  within the U-shape. 
     Each mounting ear  13  defines a co-linear thru-hole  14 . The thru-holes are sized to receive a corresponding spring pin  15  therein, with each pin extending toward the interior of the U-shape. The spring pins  15  can extend through opposite walls  17   a  and  17   b  of the hub  17 , as depicted in FIG. 3, to mount the tablet plate  11  to the hub for rotation therewith. At a rotational position in which the tablet plate  11  is in a plane sharing one axis with the chair seat, the spring pins  15  can engage detents  35  defined on opposite sides of the short arm  22  of mounting bar  20 . The detents  35  cooperate with the ends of the pins  15  to resist rotation of the hub  17  and tablet plate when the pins reside within the detents. However, the spring pins are configured to allow the ends of the pins to slide out of the detents upon application of a moderate force rotating the hub  17  relative to the short arm  22 . The tablet plate  11  remains free to pivot about the axis of the spring pins  15 , and relative to the hub, permitting movement of the tablet plate between a horizontal and vertical position. 
     The hub  17  is preferably formed substantially entirely of nylon or a similar low-friction material. Most importantly, the hub opening  18  must have a low friction characteristic so that the hub, and therefor the tablet plate  11 , can freely rotate about the mounting bar. Likewise, the pin bores  16   a  and  16   b  must have a low friction characteristic so that the spring pins can pivot freely as the tablet plate is pivoted relative to the hub. In addition, the spring pins must be able to freely translate axially toward the detents  35  in the mounting bar. 
     The operation of the chair tablet arm assembly  50  is as follows. The stowed position  10 ′ depicted in FIG. 5 presents a well-situated location for the tablet when it is not in use. In the stowed position  10 ′, the tablet plate  11  is oriented in a vertical position, perpendicular to the chair seat. The tablet plate mounting ears  13  are located at the top-most end of the tablet plate, which hangs from the pivot pins  15 . To re-position the tablet plate to the deployed position  10 ″ depicted in FIG. 4, two steps are required. First, the tablet plate  11  is rotated within the vertical plane, rotating the hub  17  about the short arm  22  of the mounting bar  20 . At 180-degrees of rotation, the rotation position at which the mounting ears  13  are located at the bottom-most end of the tablet plate, the spring pins  15  engage the detent bores  35  on the mounting bar  20 , resisting further rotation. Second, the tablet plate  11  is pivoted about the pivot pins  15  from the vertical position toward the chair seat until the tablet plate contacts and is supported by the rest bracket  24  in the deployed position  10 ″ depicted in FIG.  2 . Completion of the steps and movement of the tablet plate  11  in reverse order will return the tablet plate to the stowed position  10 ′ depicted in FIG.  5 . 
     In a further embodiment of the invention, as depicted in FIG. 6, a tablet arm apparatus  50  contemplates a tablet plate  51  rotationally attached to an articulating arm assembly  81 . The assembly includes a slotted washer  53 , a long arm  61 , a pivot rod assembly  65 , and a short arm  77 . The apparatus  50  can be generally constructed of plastic or lightweight metal and can be attached to a member of a chair with the short arm  77 , preferably as an integral part of the chair design. The vertical stowed position  50 ′ of the apparatus, at the side of the chair, is depicted in FIG. 7. A first deployed position  50 ″ of the apparatus with tablet plate  51  parallel to the seat of the chair and to the outside of the arm of the chair is depicted in FIG. 8. A second deployed position  50 ′″ above and parallel to the seat of the chair is further depicted in FIG.  8 . The first deployed position  50 ″ and stowed position  50 ′ facilitate access to or exit from the seat of the chair. The first and second deployed positions  50 ″ and  50 ′″ each provide a work surface functional to a person seated in the chair. 
     Referring to FIG. 6, the short arm  77  is pivotally mounted at one end  77   b  to the chair arm  58 . The other end  77   a  of the short arm  77  is attached to the pivot sleeve  69  of a pivot rod assembly  65 . One end  61   a  of the long arm  61  can be attached to a pivot rod  66  of the pivot rod assembly  65 . The pivot rod assembly  65  provides a means for the ends  61   a  and  77   b  of the arms  61  and  77 , respectively, which are not attached to pivot rod assembly, to articulate from a position extended and opposite each other, as depicted in FIG. 6, to a position toward each other, as depicted in FIG.  7 . The articulating translation allows tablet plate  51  to be rotated from the stowed position  50 ′ depicted in FIG. 7 to the first deployed position  50 ″ along the outside of the chair arm  58 , depicted in FIG.  8 . The pivotable mounting of the short arm  77 , permits the entire tablet arm assembly  50  to pivot between the two deployed positions  50 ″ to  50 ′″, both depicted in FIG.  8 . 
     Referring to FIG. 6, the short arm  77  can be constructed of a section of rectangular tubing. The rectangular shape forms two wider sides  77   c  and  77   d  and two narrower sides  77   e  and  77   f.  Two thru-holes  78  are bored in the wider sides  77   c  and  77   d,  near one end  77   b,  to provide means for pivotably mounting the short arm  77  to a member  58  of the chair (FIG.  8 ). At the same end  77   b  of the short arm  77  an end cap  80  in inserted to close the open tubing end. The opposite end  77   a  of the short arm  77  is preferably cut at an angle and is attached to pivot sleeve  69  of the pivot rod assembly  65 . 
     The pivot rod assembly  65  includes the pivot rod  66  and pivot sleeve  69 , as well as a locking spring  72 , a washer  73 , and a retaining nut  74 . The pivot rod assembly  65  provides a means for the pivot rod  66  to rotate relative to the pivot sleeve  69  and for the resulting articulation of the attached short arm  77  and the attached long arm  61  to stop when the arm assembly is in the extended position depicted in FIG.  6 . The cylindrical pivot rod  66  can have an end  66   a  attached to the angled end  61   a  of the long arm  61 . The pivot rod  66  extends through the open cylinder formed by the pivot sleeve  69  with each end  66   a  and  66   b  situated beyond the respective end of the pivot sleeve. 
     In the preferred embodiment, a locking pin  75  extends through a hole  67  bored through a midpoint along the pivot rod  66 , with the pin  75  situated adjacent end  69   a  of the pivot sleeve. The pivot rod  66  further includes an opposite threaded end  68  configured for receiving the retaining nut  74 . The nut is used to secure the washer  73  and locking spring  72  between the retaining nut  74  and the end  69   b  of the pivot sleeve  69 . In this arrangement, the locking spring  72  biases the pivot rod  66  toward the end  69   b  of the pivot sleeve. More specifically, the locking spring biases the pivot rod  66  so that the locking pin  75  can reside within notches  70  and  71  cut in oppose sides of the end  69   a  of the pivot sleeve  69 , as shown in FIG.  6 . When the locking pin  75  is so situated, the long arm  61  is fixed against rotation relative to the pivot sleeve  69 . Rotation is permitted when the pivot rod  66  is pushed toward end  69   a  of the sleeve  69 , against the force of the locking spring  72 , to thereby release the locking pin  75  from the notches  70  and  71 . 
     The long arm  61  can be constructed of a section of rectangular tubing of the same type as the short arm  77 . One end  61   a  of the long arm  61  is angled and attached to an end  66   a  of the pivot rod  66 . The other end  61   b  of the long arm  61  can be rotationally connected to the tablet plate  51  using rotational pin  59 , support disk  56 , a slotted washer  53 , and stop pin  55 . The long arm  61  can have an end cap  62  enclosing the tube end near the tablet plate  51 . 
     The arm  61  can define a thru-hole  63  sized to receive the rotational pin  59  therethrough. The pin  59  is preferably affixed to the underside of the tablet plate  51 , such as by press-fit into a corresponding bore in the plate. Most preferably, the pin passes through a support disk  56  interposed between the tablet plate  51  and the long arm  61 , and then through the hole  63  in the arm  61 . A retaining cap  64  can engage the pin  59  to fasten the rotational pin, while permitting the pin to rotate relative to the arm  61 . 
     In a further feature of this embodiment, the slotted washer  53  is preferably mounted to the long arm  61 , with the support disk  56  disposed between the washer  53  and the tablet plate  51 . The washer  53  defines a slot  54  along an arc of a constant radius and extending for less than 360-degrees around the washer. The slotted washer  53  is configured to cooperate with a stop pin  55  extending from the underside of the tablet plate  51 . In other words, the stop pin  55  rides within the slot  54  of the washer to control the range of rotational movement of the tablet plate  51  relative to the long arm  61 . Preferably, the slot  54  extends along an arc of about 135-degrees so that the user can find a comfortable orientation of the tablet plate in use. The tablet plate  51  can define multiple mounting holes  52  therethrough by which a work surface can be attached. 
     The operation of the chair tablet articulating arm assembly  50  is as follows. The stowed position  50 ′ depicted in FIG. 7 presents a well-situated location for the tablet when it is not in use. In the stowed position  50 ′, the tablet plate  51  can be oriented in a vertical position, perpendicular to the chair seat. To re-position the tablet plate  51  to the first deployed position  50 ″, depicted in FIG. 8, the tablet plate can be translated to the horizontal position, parallel to the chair seat, by the pivoting of the long arm  61  at the pivot rod assembly  65 , until the locking pin  75  engages the locking notches  70  and  71 . The tablet plate  51  is thereby located outside the chair arm  58 , at position  50 ″ depicted in FIG.  8 . 
     To re-position the tablet plate  51  over the seat of the chair, such as in the second deployed position  50 ′″ depicted in FIG. 8, the entire arm assembly can be simply rotated about the pivotable mounting fastener  79  located near the end of short arm  77 . Completion of the steps and movement of the assembly in reverse order can return the tablet plate to the stowed position  50 ′ depicted in FIG.  7 . 
     While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. It should be understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.