Abstract:
Apparatus for adjusting the longitudinal and angular position of a work surface support leg. The leg passes through a channel in a cap held via a spring and pin to a base affixed to the work surface. The leg&#39;s angular position is adjusted by rotating the cap, which moves a tooth through a series of mating depressions. The longitudinal position is adjusted by moving the leg which has a series of notches that mate with a locking tooth in the cap. A knob interfaces with the cap via a rotary cam having high and low steps and a matching cam rider. The low step allows separation between the cap and base and the high step locks the cap to the base, thereby locking in the adjustment setting for the leg.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 60/948,459, filed Jul. 7, 2007 by Roy P. Conley. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to work supports, and more particularly to adjustable legs for portable desk tops. 
     BACKGROUND OF THE INVENTION 
     Assistive Technology (AT) is a generic term that includes assistive, adaptive, and rehabilitative devices and the process used in selecting, locating, and using them. AT promotes greater independence for people with disabilities by enabling them to perform tasks that they were formerly unable to accomplish, or had great difficulty accomplishing, by providing enhancements to or changed methods of interacting with the technology needed to accomplish such tasks. According to disability advocates, technology, all too often, is created without regard to people with disabilities, and unnecessary barriers make new technology inaccessible to hundreds of millions. Universal accessibility (universal design) means excellent usability, particularly for people with disabilities. But, argue advocates of assistive technology, universally accessible technology also yields great rewards to any user; widely accessible design is good design, they say. The classic example of an assistive technology that has improved everyone&#39;s life is the curb cuts in the sidewalk at street crossings. While these curb cuts surely enable pedestrians with mobility impairments to cross the street, they have also aided parents with carriages and strollers, shoppers with carts, and travelers and workers with pull-type bags, not to mention bicyclists, skateboarders and inline skaters. 
     Previous art has disclosed portable desks such as lap desks and bed tables. These provide a generally planar rigid platform as a small portable work surface (i.e., desktop) that may be supported on legs, but in many cases the legs aren&#39;t adjustable in terms of height and/or angle relative to the plane of the desktop. As assistive technology, these desks provide not just convenience for the able bodied, but provide needed alternative placement of, for example, keyboards and mice (e.g., at a wheelchair), and/or provide support for arm(s) or upper body of those who are handicapped by back and/or muscular problems, such as Parkinson&#39;s disease, multiple sclerosis and the like. Thus, for the latter, the desk becomes not only a work surface (desktop for items being worked on), but also a “work support” in that the desk supports both the work and, at least partially, the worker. 
     Particularly for the handicapped, therefore, there is a great need for adjustable desk (work support) legs to accommodate, for example, a user&#39;s height and leg/lap size; or for example, different situational placements. For example, the desk may need different leg placement when used in a wheelchair versus in a bed. For example, a painter with back and arm support problems may want to adjust the leg height according to the portion of a canvas that he/she is painting. Thus the desk/work support may need to be adjusted high or low, level or tilted in any direction, with legs angled back or forward to reach an appropriate base (e.g., angled back to the seat of a wheelchair), and so on. Furthermore, for those with disabilities, adjustments of the legs should be as simple and quick as possible, as well as not requiring much strength, mobility, or dexterity of arm, hand, or fingers. 
     Work support placement changes generally require adjustment of both leg length and angle, often simultaneously for a given leg, and usually front and back legs require different adjustments (assuming a typical arrangement of four legs near the corners of a rectangular desktop). In such cases, it is also common to need the same adjustment made for at least a pair of the legs (e.g., both back legs). Thus it is desirable to be able to recognize an adjustment setting made on one leg such that the setting can be readily duplicated on another leg. 
     Thus, it is an object of the present invention to provide adjustable work support legs that accommodate the limitations imposed upon people with disabilities, particularly relating to the back and/or muscles, while simultaneously providing superior convenience for the able bodied. 
     More particularly, it is an object to provide individual leg adjusters that can be operated by one hand with minimal requirements of strength, dexterity, and movement range (mobility). It is a further object to enable simultaneous adjustment of both length and angle for a leg, and for the adjustment to be restricted to discrete angle and length (longitudinal) adjustment steps that provide easily controlled, recognizable and duplicatable leg positioning. 
     BRIEF SUMMARY OF THE INVENTION 
     According to the invention, a leg adjuster, comprising a cap, base, and knob, is held together by an axial pin with a compression spring biasing the cap against the base. The base is attached to a platform (work surface, work support, desk top), and a leg passes through a channel in the cap, the channel being open to the base. The legs are supplied in several standard lengths with optional padded extenders. The leg adjuster is unlocked by a discrete turn of the knob which rides on a rotary cam surface. The rotary cam has a high step limiting rotation to a discrete turn, a medium step that prevents separation of the mechanism, thereby locking it at a particular adjustment, and a low step which unlocks the mechanism to allow separation of the cap from the base, thereby enabling simultaneous but one-handed adjustment of the longitudinal and angular position of the leg. Notches in the leg mesh with a locking tooth as the leg slides between the channel openings and the base. An O-ring in an end groove on the leg prevents the leg from falling through the adjuster. Radial teeth in the base mate with radial depressions in the cap as the cap is rotated relative to the base. The invention thus affords fast, convenient, stepwise (“click-stop”) adjustment of the longitudinal and angular position of the legs. 
     Other objects, features and advantages of the invention will become apparent in light of the following description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawing figures. The figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these preferred embodiments, it should be understood that it is not intended to limit the spirit and scope of the invention to these particular embodiments. 
       Certain elements in selected ones of the drawings may be illustrated not-to-scale, for illustrative clarity. The cross-sectional views, if any, presented herein may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a true cross-sectional view, for illustrative clarity. 
       Elements of the figures can be numbered such that similar (including identical) elements may be referred to with similar numbers in a single drawing. For example, each of a plurality of elements collectively referred to as  199  may be referred to individually as  199   a ,  199   b ,  199   c , etc. Or, related but modified elements may have the same number but are distinguished by primes. For example,  109 ,  109 ′, and  109 ″ are three different elements which are similar or related in some way, but have significant modifications. Such relationships, if any, between similar elements in the same or different figures will become apparent throughout the specification, including, if applicable, in the claims and abstract. 
       The structure, operation, and advantages of the present preferred embodiment of the invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of a work support with four leg adjusters, according to the invention; 
         FIG. 2  is a side view of the work support showing details of an adjuster base, according to the invention; 
         FIG. 3  is a perspective view of a leg extension that can be mated with a work support leg, according to the invention; 
         FIG. 4  is a perspective side view of a cap portion of the leg adjuster, according to the invention; 
         FIG. 5  is a perspective bottom view of the cap holding the work support leg (ghosted), according to the invention; 
         FIG. 6  is a perspective top view of the cap holding the work support leg, according to the invention; 
         FIG. 7  is a perspective side view of a knob for use in locking the leg adjuster, according to the invention; 
         FIG. 8  is a side view of the knob, cap, and base held together by a pin, an obstructing shoulder portion of the cap having been cut away, according to the invention; 
         FIG. 8A  is a magnified view of a cam portion of the adjuster as indicated by the circular outline in  FIG. 8 ; and 
         FIG. 9  is a cross-sectional side view of the adjuster, the view taken as indicated by the line  9  in  FIG. 8 , according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an overall perspective view of an inventive work support  100  illustrating several inventive forms of adjustable legs  104 , not all of which would be used combined as shown. The work support  100  includes a platform  102  with leg adjusters  120 , typically four as illustrated by the embodiment of  FIG. 1 . Each leg adjuster  120  comprises a base  125  that is molded as part of, or attached through some other means to, the side of the platform  102 , a rotating cap  106 , a manual locking knob  134  (preferably wing shaped), and an adjustable leg  104 . Each leg  104  comprises a series of longitudinally spaced notches  110  (e.g., a circumferential groove on a cylindrical leg post), a protrusion  114  (e.g., O-ring) at each leg end  109 , and a leg shank  108  of length L 1  onto which a leg extension  112  may be attached to increase the effective length of the leg  104 . 
       FIG. 2  shows a side view of the work support  100  with the platform  102 , leg adjuster  120 , and an adjuster base  125  onto which the cap  106  can be movably attached. The base  125  has at least one, and preferably an arcuate series of, teeth  126  (e.g., radial ridges) spaced around an arc having a radius of curvature, and a central hole  128  at the axis of the radius of curvature. The purposes of the teeth  126  and the hole  128  will be elucidated later in this description. 
       FIG. 3  shows further detail of the leg extension  112 . A short cavity  113  is dimensioned to accept the leg shank  108  such that friction from the O-ring  114  holds the leg extension  112  in place. The leg extension  112  thus allows customizability in the length of the leg  104  and is optionally covered at least at the bottom end with a cushioning and/or non-slip material  146  (e.g., resilient foam). 
       FIGS. 4 and 5  show detailed perspective views of the cap  106 . The cap  106  is arranged around a rotational axis defined by an axle pin  130  passing through a center hole  128 , and has a planar first axial side  144 , the plane being normal to the axle pin  130 . A channel  123  crosses the cap  106  parallel to the first axial side  144  of the cap  106 , is open on the first axial side  144 , and is dimensioned to hold the leg  104  between the channel  123  and the plane defined by the first axial side  144 . Protruding into the channel  123  is a locking tooth  122  (e.g., a ridge) that is dimensioned to mate with the notches  110  in the leg  104  when it is in the channel  123 . A bottom view of the cap  106  with a mated leg  104  (a portion thereof being shown in ghosted outline) is illustrated in  FIG. 5 . Thus, a leg  104  properly placed in the channel  123  is held against longitudinal leg movement by the locking tooth  122 , especially when the leg  104  is pressured along a side of it opposite the locking tooth  122 . The illustrated embodiment of the cap  106  is made of molded plastic, so it is hollow to minimize plastic use. Therefore the channel  123  is implemented as a series of four plastic ridges, each one of which forms a short portion of the channel  123  across its width, as shown. Likewise, the tooth  122  is another ridge with a top edge that protrudes into the path of the channel  123 . 
     The cap  106  has an arcuate series of spaced-apart depressions  124  which are dimensioned to mate with the one or more teeth  126  of the base  125 . The teeth  126  are also shaped such that when the teeth  126  are mated with the depressions  124 , the cap  106  can be rotated about the base hole  128  such that the teeth  126  move out of the depressions  124  to which they are mated and into adjacent depressions  124 . Thus the cap  106 , when rotated, will change the angular position of the leg  104  when it is in the channel  123 . Although the drawings discussed herein show depressions  124  on the cap  106  and the teeth  126  on the base  125 , the depressions  124  and the tooth/teeth can of course be on either the cap  106  or the base  125 . 
       FIG. 6  shows a top view of the cap with a mated leg  104 . An axle pin  130  passes through a spring  132 , preferably a compression spring, and a central cap hole  129 , which is rimmed by a rotary cam  138  comprising at least one, but preferably four, two-step  137  cam sets. Although the embodiment disclosed herein shows a coiled spring  132 , the invention can accommodate other types of springs  132  (e.g. a beveled spring washer). The spring  132  biases the cap  106  against the leg  104 . At each end of the leg  104  the O-ring  114  is stretch-fitted into an end groove  116 . In addition to providing friction to hold the leg extension  112 , the O-ring  114  also serves as a laterally protruding end stop to prevent the leg  104  from slipping through and out of the channel  123 . The leg  104  also has an overall leg length L 2  that can be varied by providing different lengths L 1  for the shank  108 . Two shank lengths L 1  are shown (compare  FIGS. 1 and 6 ), though an array of lengths can be accommodated, e.g., 6″, 9″, 12″. For example, the leg  104  in  FIG. 6  is 6″ (six inches) long (L 2 ), comprising a shank length L 1  of 1.5″, a 3″ notched portion divided into 1″ increments by the notches  110 , and a top end  109  also being 1.5 inches long. For a 9″ version, the length L 1  of the shank  108  is increased to 4.5″ and everything else stays the same. 
       FIG. 8  shows a side view, while  FIG. 9  shows the same view in cross-section, of the knob  134 , the cap  106 , and the base  125 , through all of which passes the axle pin  130 . A head or clip ring  142  in a groove on one end of the axle pin  130  and a clip ring  142  in a groove on the other end hold everything together with pressure from the spring  132  biasing the cap  106  against the base  125 . The knob shank  140  is hollow to contain the pin  130  while a number of cam riders  136  equal to the number of cam sets in the rotary cam  138  rim one end of the knob shank  140 . This is shown in further detail in  FIG. 7 . Although only one cam set  138  and one cam rider  136  are needed, four are shown as preferred in order to prevent wobbling of the knob  134 . Thus, the cam rider(s)  136  of the knob  134  can be mated with the cam (sets)  138  of the cap  106 , as shown in the close-up view of  FIG. 8A . For a given cam set  138 , when the knob  134  is in the “LOCK” position, the cam rider  136  rests on a middle step  137   b  of the cam  138 . A top step  137   c  is a stop that prevents any further rotation of the knob  134  in the “LOCK” direction, providing a discrete stopping point for the cam rider  136 . When the knob  134  is turned in the “UNLOCK” direction, the cam rider  136  moves to the bottom step  137   a , while another top step  137   c  once again stops any further rotation. The extra space afforded by the bottom step  137   c  allows the cap  106  to be moved out against the spring bias such that the teeth  126  are no longer mated with the depressions  124 . This allows the angular position of an object placed in the channel  123  (e.g. a leg) to be adjusted by applying torque to the cap  106 . 
     The unique locking and unlocking ability afforded by the knob  134  and cam  138 , combined with a click-stop system, allows simultaneous, one-handed adjustment of the angular and longitudinal position of the leg  104 . When one wants to make leg  104  adjustments, one merely needs to turn the knob  134  in a discrete turn to the “UNLOCK” position, which enables adjustment of the leg  104  in discrete units of adjustment. Moreover, even while unlocked, the adjuster  120  will hold any given leg  104  position setting by spring bias  132  until light force is exerted to either turn the cap  106  or longitudinally push/pull the leg  104  from one “click-stop” setting to the next, either angularly or longitudinally, individually or simultaneously. The spring  132  causes the movements to “click” and stop when the leg  104  or cap  106  moves to a new mating engagement of tooth/depression ( 122 / 110  or  126 / 124 , respectively). Because the click stop positions are spaced apart in relatively large increments (e.g., one inch spacing between leg grooves  110 , e.g., fifteen degree angular increments between cap/base depressions  124 ) a leg position setting made and locked in on a first leg  104  is easily recognized for duplicating on a second leg  104  of the work support  100 . Again one-handed adjustment is enabled since a plurality of legs  104  can be adjusted one at a time. 
     Thus, longitudinal and angular adjustment of the leg  104  is controlled by a single knob  134 , allowing simple and quick click-stop style adjustment. This is especially important for people with physical handicaps including, for example, limited arm/hand dexterity, strength, and/or mobility, for whom extra convenience can mean the difference between the ability and inability to adjust a work support by themselves. This also allows the inventive work support  100  to be used in a variety of situations and for a variety of purposes (e.g. in bed for reading a book, in a chair or wheelchair for holding a laptop or keyboard, etc.). Thus, the easily adjustable inventive work support  100  offers superior convenience for both handicapped and able-bodied people. 
     Although 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 being understood that only 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. Undoubtedly, many other “variations” on the “themes” set forth hereinabove will occur to one having ordinary skill in the art to which the present invention most nearly pertains, and such variations are intended to be within the scope of the invention, as disclosed herein.