Patent Publication Number: US-6705239-B2

Title: Adjustable table assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119(e) on U.S. Provisional Application No. 60/313,229 entitled ADJUSTABLE TABLE ASSEMBLY, filed on Aug. 17, 2001, by James E. Doyle, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an adjustable table and particularly to a table leg assembly which allows macro and micro adjustment of the height of the table work surface. 
     In current ergonomic work spaces, it is desirable to provide personnel with work areas which accommodate different working positions, either sitting or standing, and for personnel of different heights. It has been discovered that work surface heights of about 22″ to 24″ from the floor is appropriate for female workers when seated, while approximately 24″ to 28″ from the floor is an average comfortable height for male workers. On the other hand, in a standing position, work surface heights of from about 37″ to 42″ for female workers and about 39″ to 46″ for male workers are desirable. Thus, to accommodate both male and female workers in sitting and standing positions, a relatively large range of motion (i.e., 22″ to 46″) is desirable for a given work surface. Several proposals have been made for providing multiple leg telescopic actuators, such as described in U.S. patent application Ser. No. 09/573,065 filed May 17, 2000, entitled ADJUSTABLE LEG ASSEMBLY, and U.S. patent application Ser. No. 09/901,225 filed Jul. 9, 2001, entitled TELESCOPIC LINEAR ACTUATOR, the disclosures of which are incorporated herein by reference. The use of multiple telescopic legs using two or more interactive telescopic sections satisfies the desired height adjustment requirement, however, such telescopic legs can be somewhat expensive to manufacture insofar as they require additional parts and assembly procedures. Conventional single stage screw-type actuators are capable of providing 24″ of adjustment, however, mechanical restrictions in the design of telescoping guide mechanisms make it impossible to achieve the specified seated heights within this range of motion. The range of work surface heights should cater to the intended user rather than an entire population of users. 
     As a result, there remains a need for an adjustable work surface which allows a range of motion for male and female workers between standing and sitting positions and which is inexpensive to manufacture and utilizes a single screw actuating mechanism. 
     SUMMARY OF THE INVENTION 
     The table assembly of the present invention satisfies this need by providing at least one telescopic leg assembly, which is motor-actuated. The leg assembly has an outer leg with adjustable feet to provide micro adjustment of the height of the work surface. The combination of a telescopic support leg and adjustable feet thus provides macro and micro adjustment of the table leg and provide additional height adjustment to accommodate workers of different stature. Preferably, the leg assembly includes extruded leg members with an extruded track formed in an outer leg which receives the adjustable feet and can also accommodate cross-struts for providing additional support to the table. 
     These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a table assembly embodying the present invention; 
     FIG. 2A is an end elevational view of one of the leg assemblies for the table assembly, shown with the feet in a position for lowering the overall height of the table; 
     FIG. 2B is a side elevational view of one of the leg assemblies shown with the feet in a position to raise the table to a maximum height; 
     FIG. 3 is an enlarged partial vertical cross-sectional view through one of the leg assemblies; 
     FIG. 4 is an enlarged cross-sectional view of the upper end of the leg assembly shown in FIG. 3; 
     FIG. 5 is an enlarged vertical cross-sectional view of the interface between the upper leg and lower leg of the leg assembly, taken along section line V—V of FIG. 6; 
     FIG. 6 is a fragmentary perspective view of the interface shown in FIG. 5; 
     FIG. 7 is a cross-sectional view of the interface between the upper and lower legs taken along section lines VII—VII of FIG. 6; 
     FIG. 8 is a perspective view of one of the guides employed for slidably supporting the inner leg with respect to the outer leg; 
     FIG. 9 is a horizontal cross-sectional view of the inner leg extrusions; 
     FIG. 10 is a horizontal cross-sectional view of the outer leg extrusion; 
     FIG. 11 is a fragmentary perspective view of a stretcher employed for coupling the leg assemblies; 
     FIG. 12 is a fragmentary cross-sectional view taken through section lines XII—XII of FIG. 11; 
     FIG. 13 is a fragmentary enlarged vertical cross sectional view of the foot area of one of the leg assemblies shown in FIGS. 1,  2 A,  2 B and  3 ; 
     FIG. 14 is a fragmentary perspective view of the foot area of the leg assembly shown in FIGS. 1,  2 A,  2 B and  3 ; 
     FIG. 15 is an enlarged fragmentary cross-sectional view of one of the feet shown in FIG. 14, taken along section lines XV—XV in FIG. 14; 
     FIG. 16 is a side elevational view, partly broken-away in phantom form, of an alternative foot assembly for use in connection with the table assembly of the present invention; and 
     FIG. 17 is a fragmentary vertical cross-sectional view of an alternate mounting system for the feet of the table assembly of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIGS. 1,  2 A, and  2 B, there is shown a table assembly  10  embodying the present invention. Assembly  10  includes a generally planar work surface or table top  12  coupled to a pair of substantially identical adjustable leg assemblies  20 . Each of the identical leg assemblies  20  includes an inner leg  30  telescopically extending with an outer leg  40  and a pair of adjustable feet  50 ,  52 , which allow the table to move from an adjustable lowered position approximately 24″ to 28″ high for the work surface  12  to an adjustable raised position approximately 40″ to 44″ in height in the raised position, as illustrated in FIGS. 2A and  2 B, respectively. The inner and outer legs, as described below, are telescopically mounted with respect to one another and movable utilizing a motorized screw jack assembly to provide macro adjustment of approximately 16″ between the lowermost position and an uppermost or raised position. The feet  50 ,  52  can be adjusted along the outer leg  40  as shown in FIGS. 2A and 2B to provide micro adjustment of approximately 4″ between a lower position, shown in FIG. 2A, and an upper position, shown in FIG. 2B, as described below. Thus, the table assembly  10  has the ability to provide motor-driven adjustment between selected first and second raised and first and second lowered positions, depending on the position of the adjustable feet  50 ,  52  on the outer leg  40 . Inner legs  30  are mounted to the undersurface  11  of work surface  12  by means of a motor enclosure  14 . A motor control  13  is coupled to a supply of operating power (not shown) and selectively applies electrical power to a reversible DC electric motor  16  (FIGS. 3 and 4) in each of the leg assemblies  20  to provide macro adjustment of the work surface  12  over a range of about 16″. 
     The inner and outer legs  30 ,  40 , respectively, are shown in horizontal cross-sectional detail in FIGS. 9 and 10 and are extruded of a suitable material, such as aluminum, which can be anodized, plated, or painted to provide a desired appearance. The inner leg  30  has a generally ovular/rectangular cross section with convexly curved side walls  31  and  32  and flattened end walls  33  and  34 . At the inner junction of the side and end walls, there are formed sockets  35  at the four corners for receiving self-threading screws (not shown) for the attachment of slides  80  (FIGS. 7 and 8) to the bottom of inner leg  30 , as seen in FIG. 5, and the top of inner leg  30  to the motor enclosure, as best seen in FIG.  4 . 
     The outer leg  40  also is an extruded member having a somewhat flattened ovular/rectangular cross section with side walls  41  and  42  and end walls  43  and  44 , with the intersection thereof including screw-receiving sockets  45  at the junction of the side and end walls for receiving mounting screws for securing the base  64 , as seen in FIG.  13  and described below, and bezel  70  (FIG.  6 ). Integrally formed with outer walls  43 ,  44  are L-shaped opposed facing legs  46  and  48  external to each of the end walls  43 ,  44  to define T-shaped slots  49  which, as described in greater detail below, adjustably receives T-nuts for mounting the feet  50 ,  52  as well as a stretcher  25 , which extends between each of the leg assemblies  20  to the outer legs  40 , as shown in FIGS.  1  and  11 - 14 . 
     As seen in FIGS. 11 and 12, the stretcher  25  includes a pair of spaced apertures  26  at each end for receiving threaded fasteners, such as bolts  22 , which extends through the aperture and stretcher  25  to a T-shaped nut  28  fitted within T-shaped slot  49  of the outer leg  40  for securing each end of stretcher  25  to the outer leg. As seen in FIG. 11, two such fasteners  22  and associated T-shaped nuts  28  may be employed at each end of the stretcher. The stretcher provides lateral stability to the table assembly, as seen in FIG. 1, and typically will be placed near the upper end of outer leg  40 . Additional stretchers may be employed and one may be placed at the lower end of the table at the feet  50 ,  52  to provide a foot rest for the table assembly, if desired. Additionally, a stretcher may be placed on both the front and rear end walls  43 ,  44  of the outer leg  40 , if desired. Before describing the micro adjustment of the feet  50 ,  52  along the T-shaped slot  49  defining elongated, vertically extending tracks in the outer leg  40 , a description of the motorized telescopic mounting of the inner leg  30  to the outer leg  40  is described in connection with FIGS. 3-8. 
     Each of the leg assemblies  20  are substantially identical, therefore, a description of only one of the leg assemblies follows. The leg assemblies  20  are coupled to work surface  12 , as noted below, by motor enclosure  14 , which includes apertures  15  (FIG. 4) for receiving fasteners which attach the motor enclosure  14  to the lower surface  11  of the table top defining work surface  12 . Motor enclosure  14  defines an open housing for receiving a drive motor  16  having an angled gear box  17  keyed to a threaded power screw  18  which extends through a collar  13  at the top of the power screw and a thrust bearing  19 . Motor enclosure  14  is secured to the open, upper end of the inner leg  30  and includes an aperture for receiving the collar and thrust bearing such that, upon actuation of motor  16 , the power screw  18  rotates for raising and lowering the inner leg  30  with respect to the outer leg  40 . 
     The power screw  18  is coupled, as best seen in FIG. 5, to an internally threaded power nut  60  secured to a riser tube  62 , which is concentric with and extends upwardly from the base plate  64  (FIG. 13) secured to outer leg  40 . Tube  62  is welded at  61  to the lower mounting plate  64  which rests on the support surface or floor at which the table assembly  10  is located. The power screw is secured to a guide washer  65  (FIG. 5) by means of a threaded fastener  66  to control the motion of the power screw as it slidably extends within riser tube  62 . Thus, rotation of the power screw  18  by activation of motor  16 , which is supplied by suitable electrical power from control  13  to provide reverse polarity activation of the reversible DC electrical motor in a conventional manner, causes the power screw to raise and lower, carrying with it the inner leg  30  attached at its upper end to the mounting bracket  14  and, therefore, work surface  12 . 
     The lower end of inner leg  30  is guidably supported at the upper end of the outer leg  40  by means of a guide bezel  70  (FIG.  6 ), which has four apertures  72  in each of the corners for receiving fastening screws extending into apertures  45  in outer leg  40 . Bezel  70  includes a central opening  75  generally conforming to the outer peripheral shape of inner leg  30 , thereby providing stability to the inner leg at the interface of outer and inner legs, as seen in FIG.  6 . The lower end of inner leg  30  is supported within the internal U-shaped channels  47  (FIGS. 7 and 10) of outer leg  40  by means of a pair of lubricious polymeric slides  80  with one such identical slide  80  being shown in detail in FIG.  8 . Each of the slides  80  comprises a generally rectangular block of polymeric material, such as acetal, polyvinyl chloride, ABS, or the like, and has a pair of elongated apertures  81 ,  82  for receiving fastening screws extending through apertures  81 ,  82  into apertures  35  on inner leg  30 . Slides  80  include a rectangular outwardly extending projection  84  which fits within guide channels  47  with the elongated apertures  81 ,  82  allowing for appropriate adjustment of the slides  80  with respect to the inner contacting surfaces of channels  47  of outer leg  40 . Thus, the lower end of inner leg  30  is supported by a pair of lubricious slides  80  as it moves within outer leg  40  while the junction of the inner and outer legs  30  and  40  is also supported by the guide bezel  70 . 
     The lower end of each of the outer legs  40  is supported on the floor of the installation supporting the table by means of the pair of feet  50 ,  52 , shown in FIGS. 1,  2 A,  2 B and  3 , and which are attached as best seen in FIGS. 14 and 15 now described. Feet  50 ,  52  are substantially identical and each includes floor engaging pad  51  which has a generally horizontal extending surface and upwardly inclined leg  53  and an attachment end  54 , which has a vertically extending surface having flanges with apertures  55  (FIG. 15) for receiving attaching bolts  56  which extend through apertures  55  and thread into a T-nut  57  in slots  49  in outer leg  40  to allow the adjustment of each of the feet  50 ,  52 , as seen in FIGS. 2A and 2B, by the loosening of bolts  56  and sliding feet  50 ,  52  upwardly and downwardly within slots  49 . Depending upon the length of the feet and the angle between pad  51  and flange  54  of each of the legs, a vertical adjustment of at least 4″ can be provided to provide a micro adjustment of the work surface  12 . The foot is designed so that it provides stability to the table and it can be adjusted in the lower leg T-slot to achieve 4″ of adjustment between the lower edge of each of the legs  50 ,  52  and the vertically extending side edges  43 ,  44  of outer legs  40 . In one embodiment, angle α was approximately 45°, although angles from 30° to 60° will also provide a desired micro height adjustment. The feet  50 ,  52  should be designed to provide support for a given work surface size and can be made of cast aluminum having relief apertures  58  therein or stamped or otherwise formed of a suitable material, including a polymeric material, to provide the desired strength and stability for the table assembly  10 . 
     In place of pads  51  on the feet  50 ,  52  for the table, one of the pairs (either  50  or  52 ) may include a roller foot assembly  90 , such as shown in FIG.  16 . Roller foot assembly  90  includes a caster  92  on one end of the leg section  91  which includes a mounting flange  94  for receiving a fastening bolt, such as a bolt  56  similar to the attachment of feet  50  and  52  as shown in FIGS. 14 and 15, for coupling to a T-nut  57 , which fits within slots  49  of one side of outer leg  40 . The roller foot assembly  90 , including a caster  92  rotatably mounted to leg section  91  by means of an axle  93 , permits the table assembly  10  to be raised at one edge and easily moved along the floor to different locations. 
     Instead of having T-shaped slots  49  on the end walls  43 ,  44  of outer leg  40 , an outer leg  40 ′ (FIG. 17) may include an extrusion including T-shaped slots  49 ′ and  49 ″ formed in the side walls  41 ′ and  42 ′ as opposed to having a single T-shaped slot in each of the end walls. Thus, extrusion of outer leg  40 ′ would include four T-shaped slots, a pair on each of the opposite sides to allow a leg assembly, such as foot  50 ′ to be attached to opposite sides of the leg  40 ″ by means of attachment screws  56 ′ extending into T-shaped nuts  57 ′ in each of the slots  49 ″. Such an arrangement provides a somewhat stronger connection which may, in some embodiments, be desirable. The open tracks  49 ,  49 ′ and  49 ″ of the outer leg  40  in each embodiment may be capped by a decorative extruded polymeric cap, such as cap  98  as seen in FIGS. 6 and 7, in those areas which do not include the stretcher  25  or the feet  50 ,  52 . 
     Thus, with the table assembly of the present invention, macro adjustment is provided by the telescopic mounting of inner leg  30  to outer leg  40  by the power screw  18  and micro adjustment is provided by the adjustment of feet  50 ,  52  within the T-shaped slot  49  in the outer legs  40 . Such an arrangement allows the table to provide a greater height adjustments well as adjusting the table for different stature individuals which will provide a comfortable work surface height for sitting and standing for different individuals. 
     It will become apparent to those skilled in the art that the exact extruded shape of the inner and outer legs can be varied as desired, as can be the shape and configuration of the support feet, as long as the inner and outer legs or intermediate or other telescopic leg assemblies provide a macro adjustment of the table surface while the feet are adjustably mounted to elongated tracks within the outer legs to provide a micro adjustment of the table height. These and other modifications to the preferred embodiment of the invention as described herein can be made without departing from the spirit or scope of the invention as defined by the appended claims.