Abstract:
An improved mechanism for positioning loads of varying magnitudes, such as LCD displays, etc. The position of the load can be varied in height and angle according to the requirements of the user. The mechanism incorporates an adjustable sliding fulcrum, a support arm, a housing with four generally perpendicular channels, and a gas spring. The mechanism is initially manually adjusted for a particular load and then it automatically adjusts proportionally for the varying moments generated as the position of the load changes. The load is therefore evenly counterbalanced throughout its range of motion, and its position is maintained.

Description:
This application claims priority to U.S. provisional application Ser. No. 60/339,761, filed Dec. 10, 2001, the disclosure of which is incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   This invention relates to video display support mechanisms, specifically an improved position adjustable support for flat panel Liquid Crystal Displays (LCD), A worker at a typical computer terminal may be required to spend long hours in a somewhat constrained physical posture. In order to maintain user comfort and create the proper ergonomic position of the video display it is often necessary for the user to be able to adjust the position of his video display. Various prior art mechanisms have created devices that give the user this adjustability, however, these previous designs have inherent mechanical and functional shortcomings. 
   The typical prior art mounting systems contain various combinations of mounting brackets, support arms, friction locking knobs, ball gimbals, arcuate slots, mechanical springs, and gas springs. While the majority of these designs solve several of the typical usage problems, they are not very efficient support mechanism throughout their limited range of motion. 
   Typical single arm models such as described in prior art (U.S. Pat. No. 4,768,744 to Leeds) have their support arm pivot axis mounted in a low position near the users work surface. This has the effect of limiting the vertical adjustably range that the user might need. This is very important in a situation where the user has other furniture such as a keyboard support that has the ability to adjust to a standing height position. Due to this restriction this type of support mechanism is usually limited to supporting larger heavier CRT type displays. 
   A second typical prior art design (U.S. Pat. No. 6,019,332 to Sweere) incorporates a gas spring whose stored energy is used to counter balance the forces generated by the display. In this and numerous other existing devices the gas spring is mounted in a position such that its axis is at a relatively small distance from the pivot axis of the support arm and the angle to the axis of the support arm is relatively small. In these types of mechanisms the close proximity of the gas spring axis to the pivot axis of the arm requires the gas spring to exert very high forces to counter balance the weight of a typical display. These forces are in the range of 400-800 Newtons (N). These high forces limit the materials that can be used in the design of the highly stressed supporting components to various types of metals. 
   In order to calibrate this type of mechanism initially to provide the proper counter balance for the display, the user must adjust a bolt or screw with some type of tool such as a wrench or screw driver. This adjustment is generally difficult to accomplish due to the previously described high forces generated by the gas spring. This adjustment increases (or decreases) the distance from the axis of the gas spring to the pivot point of the arm, therefore increasing (or decreasing) the counter balance moment generated by the spring. 
   Since the distance from the axis of the gas spring to the axis of the arm pivot is relatively small, and the adjustment mechanism typically does not increase this distance significantly, the ratio of the heaviest loads that can be counter balanced to the lightest loads possible rarely exceeds 2 to 1. This can require that the user determine the weight of his display, and purchase a support mechanism with the correspondingly correct range of adjustability. This is evidenced in several existing products that are required to offer several models with different load range capabilities. 
   The design of the mechanisms that have the gas spring mounted generally parallel to the arm have an additional short coming in that the user is instructed to calibrate the counter balance while the support arm is in a horizontal position. It can be seen that through the range of articulation, the counter balancing force generated by the gas spring not only changes in magnitude, but also in direction. These changes produce a counter balancing moment that is continuously varying, with respect to the angle of the arm position and the internal characteristics of the gas spring. At the same time the moment generated by the load varies with the angle of the supporting arm. Trying to equate these two moments, as is necessary for a truly balanced condition, is very difficult, if not impossible. Since the counter balancing moments do not necessarily closely match the moments generated by the load, the load will tend to fade from the highest position toward the previously balanced horizontal position. Likewise, when the load is in the lowest position, it may be over balanced by the gas spring forces and it will tend to rise towards the horizontal position. In order to over come this inherent problem, many designs incorporate springs and polymer washers to increase the friction in the pivot areas. This in turn requires the user to apply much more force to reposition the load, because he must overcome the sum of the gas spring forces and the additional friction forces. These types of mechanisms do however operate adequately in a small range of motion. 
   In the previously mentioned prior art (Sweere), a second, manual adjustment in incorporated. This adjustment overcomes the small range of motion problem by allowing the user to access a more coarse adjustment through the use of a toothed ratchet mechanism. This in effect limits the counter balancing requirement placed on the gas spring to a smaller range of stroke. 
   SUMMARY OF THE INVENTION 
   Accordingly, my load support mechanism provides several advantages over the prior art. Included in these advantages is the mounting position of the arm pivot axis, which is located some distance above the user&#39;s working surface. This improved position allows the support arm to operate vertically through a much larger range of motion, which is very useful in the increasingly popular Sit to Stand user applications. 
   According to one aspect of the present invention, a position adjustable load support mechanism is provided that includes an arm, a channel, an attachment mechanism, and a force-producing device. The arm is supported at least partially by a movable fulcrum. The channel is adapted to constrain the movement of the fulcrum. The attachment mechanism allows a load to be attached to this arm. The arm, channel, fulcrum, and force-producing device are all arranged to create moments of force on the arm that automatically counterbalance each other over a plurality of different orientations of the arm. 
   In several prior art mechanisms, the gas spring is mounted with its axis relatively close to the pivot axis of the arm and at a small angle to the axis of the arm. This design has the inherent problem of requiring high counterbalancing forces from the gas spring, which in turn creates difficulty in adjusting the counterbalancing forces and limits the materials available for the heavily stressed components. One of the most significant aspects of the improved load support mechanism is the unique arrangement of the support arm, gas spring, and a horizontally adjustable fulcrum. This arrangement creates numerous mechanical and functional advantages. Since the distance between the axis of the gas spring and the adjustable fulcrum is relatively large compared to the prior art described previously, the force required from the gas spring to properly counter balance a load is much lower. A gas spring with a force in the 180-220N range is adequate to completely counter balance a typical video display. With this smaller counter balancing requirement two immediate advantages are evident, such as the ability to easily adjust the counter balance forces without the use of tools. A relatively small finger tip rotatable knob is adequate to adjust the position of the fulcrum and therefore change the counter balancing forces. The lower force requirement on the gas spring also allows many additional options in the design and material selection for the supporting components. The improved load support mechanism has a large portion of its components designed as molded plastics such as ABS or Nylon. This allows for many aesthetic design possibilities and less expensive components. 
   Since the fulcrum design allows additional distance between the gas spring axis and the fulcrum, the adjustability range of the improved design is greatly increased over the prior art. The improved design can be adjusted to properly counter balance loads where the ratio of the heaviest load to the lightest load can be as much as 5 to 1. In a typical prior art design as previously described, this ratio rarely exceeds 2 to 1. This is a very large advantage, because it minimizes the requirement of the user to determine the weight of his video display before purchasing a supporting mechanism, and it allows the manufacturer to produce one unit that can support a wide range of loads, again reducing the cost of the manufacturing process. 
   The improved design creates a much preferred counter balancing moment due to its ability to continuously adjust the moment generated by the gas spring to more closely match that generated by the load as it is raised and lowered. In the previously described prior art mechanism, the counter balance moments generated by the mechanism do not closely match the requirements from the load. The improved design mechanism however, creates a continuously changing moment that varies proportionally with the angle of the arm. This removes the arm angle variable from the balancing requirement and allows a much closer match of counter balancing moments. This in turn eliminates the requirement to create additional friction in the mechanism. The improved design does not require any additional friction producing components. Therefore, the amount of force required by the user to reposition the load is significantly less than in other designs, making the repositioning of the load much easier. An additional, but not less significant, advantage of being able to closely match the counter balance moment generated by the gas spring to that required by the load, is the elimination of the tendency for the load to fade toward a lower position when it is in its uppermost position or to become over counter balanced and tend to rise when in its lowest position. 
   Further objects and advantages of my invention will become apparent from a consideration of the drawings and the ensuing descriptions 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an isometric view of a load support mechanism according to one embodiment of the invention including a typical load, and a typical anchoring arrangement; 
       FIG. 2  is an exploded isometric view of the load support mechanism of  FIG. 1 ; 
       FIG. 3  is an isometric view of the main portion of the mechanism with a portion of a left housing and left arm removed to expose the internal components and details; 
       FIG. 4  is a partial bottom view of the arm assembly, showing the integral cord storage area; 
       FIG. 5  is a detailed view of a right arm showing internal details; 
       FIG. 6  is an exploded view of a ball and socket friction-producing arrangement and mounting plate; 
       FIG. 7  is an exploded view of an alternative embodiment of a load support mechanism; 
       FIG. 8  is a cross sectional view of a split ring assembly; 
       FIG. 9   a  is a force vs. displacement graph of one version of the support mechanism; 
       FIG. 9   b  is a force vs. displacement graph of an alternative version of the support mechanism; 
       FIG. 10   a  is a free body diagram of a first version of the arm, which corresponds to the force diagram of  FIG. 9   a;    
       FIG. 10   b  is a free body diagram of a second version of the arm with an offset load that corresponds to the force diagram of  FIG. 9   b ; and 
       FIG. 10   c  is a free body diagram of a second version of the arm according to an alternative embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   For purposes of description herein, the terms forward, rearward, upward, and downward relate to the load support mechanism as oriented in  FIG. 2  where the viewer&#39;s left side is considered the forward direction. As shown in  FIGS. 1 &amp; 2  the adjustable position load support mechanism includes an anchoring arrangement  10 , a load counterbalancing arrangement  30 , a housing assembly  20 , an arm assembly  40 , and a ball and socket friction producing arrangement  50  that includes a mounting plate  39  for the attachment of a load  100 , which is in this case a typical video display device. 
   The anchoring arrangement  10  is comprised of a channel shaped member  12 . To one of the channel flange surfaces  1  is rigidly attached a hollow cylinder  13 . On the same axis as the cylinder and extending through the opposite flange is a threadable member  14  and a disk shaped pad  15  which engages against the bottom surface of a desk overhang to enable a clamping operation to be effected when a clamping handle  16  is rotated. The described anchoring arrangement represents one of several provisions that can be made for this load support mechanism, other arrangements that are envisioned include an anchoring arrangement on top of a surface with inadequate thickness or having a thickness in excess of the limitations of the clamping arrangement, by a weighted tripod arrangement. A bracketed anchoring arrangement  60  ( FIG. 7 ) that anchors to a vertical surface such as a wall or typical office panel system is also envisioned. Other anchoring arrangements may be used. 
   A cable support ring  17  is disk shaped and is made from a flexible material such as flexible poly vinyl chloride (PVC). Ring  17  includes one large through hole  18  with a diameter such that it is slightly expanded when it is placed in any vertical location around cylinder  13 . Hole  18 , not being concentric with ring  17 , allows an area for the addition of several smaller through holes  19 , each with a thin slot  9  radiating from the center of holes  19  through the outer edge of ring  17 . Ring  17  allows the user to temporarily attach and control several cables that are associated with the video display equipment that is suggested by the load support mechanism. 
   The housing assembly  20  is comprised of two separate components, housing right  22   a , and housing left  22   b . These components are mirror images with the exception of three assembly posts  51   b ,  52   b ,  53   b  used by screws  31   a ,  31   b , and  31   c  respectively. Housing left  22   b  has indentions that allow the heads of screws  31   a ,  31   b , and  31   c , to be flush with or below the surface of housing left  22   b , and holes of such dimension to allow the screws to pass through without interference. Housing right has three assembly posts  51   a ,  52   a , and  53   a , that are axially aligned with those on housing left  22   b . The diameter of these three holes are such that screws  31   a ,  31   b , and  31   c  will produce internal threads in housing right at assembly, therefore securing the attachment of housing right  22   a  to housing left  22   b.    
   Both members  22   a  and  22   b  have an upper portion  41  that is generally triangular in shape and encompassing a lower portion  42  that is shaped as a semicircular extrusion with centerline axis  46 . In the preferred embodiment these components are molded from any material of sufficient structural strength. Therefore, they are generally hollow shells with internal ribs. Near the lower portion of the semicircular extrusion is a rib  43  perpendicular to axis  46 . Rib  43  contains a semicircular notch  44  concentric with axis  46 . A semicircular groove  45  with a rectangular cross section extends around lower portion  42  between rib  43  and a closed end wall  110 . At some distance above rib  43  and radiating at some specific angle is a slot  47 . Near the area of transition from the upper portion  41  to the lower portion  42  is a rib  48  ( FIG. 3 ) that includes a notch  49 . Notch  49  loosely conforms to the cross sectional shape of load counter balancing arrangement  30 . Above rib  48  and in alignment with axis  46  is a rib arrangement that produces a vertically oriented channel  24  (FIG.  2 ). A second rib arrangement that produces a horizontally oriented channel  21  roughly perpendicular to channel  24  is located approximately at the vertical midpoint of channel  24 , and extending forward into the point of the triangular upper portion  41  of housing  22   a  and  22   b . Channels  24  and  21  are on different planes. Each plane is offset a specific distance from axis  46 . A section of the outer edge of the upper portion  41  of housing right  22   a  and housing left  22   b  is offset to align with the plane of channel  21  creating edge  54 . A series of horizontal and vertical ribs  55  are incorporated to add structural strength and stability to channels  24  and  21 . When housing  22   a , and  22   b  are assembled it can be seen that they form a generally hollow structure with a cylindrical shaped lower portion  42  having circular ribs at  43  and  48 , and a triangular shaped upper portion with opposing internal rib arrangements  24  and  21 , an opening formed by edge  54  and a continuous assembly posts  51 ,  52 , and  53 . 
   Included in this support mechanism is a load counter balancing arrangement  30  comprised of an energy storage device, in this case a gas spring  27 , a strap  28 , and nut  29 . Gas spring  27  incorporates a rod end clevis  56  with a mounting hole  57  and a threaded stud  58 . Strap  28  is formed in the shape of a deep channel. The web section of the channel includes a hole  59  of sufficient diameter to accept stud  58  to which nut  29  is added to join strap  28  to gas spring  27 . Near the upper edge of the flange portions of strap  28  are two holes  95  on a single axis. Mechanism  30  is connected to the housing assembly  20  by the joining of assembly posts  51   a  &amp;  51   b  as they pass through hole  57 . 
   The arm assembly  40  is comprised of components arm right  23   a , arm left  23   b , a moveable fulcrum  26 , a threaded shaft  25 , and a hand wheel  92 . The two main arm components, arm right  23   a  and arm left  23   b , are generally mirror images with the exception of the mounting posts  61   a ,  62   a ,  63   a ,  64   a ,  65   a  ( FIG. 3 ) and their counterparts  61   b ,  62   b ,  63   b ,  64   b ,  65   b , (not visible) and the shape of their edges in cable storage area  66   a , and  66   b  as shown in FIG.  4 . Arm left  23   b  ( FIG. 2 ) has indentions that allow the heads of screws  32   a ,  32   b ,  32   c ,  32   d , and  32   e  to be flush with or below the surface of arm left and corresponding through holes of such dimension to allow the threaded portions of the screws to pass through the holes without interference. Counterpart hollow posts on arm right  23   a  incorporate blind holes of such internal diameter that screws  32   a ,  32   b ,  32   c ,  32   d , and  32   e  produce internal threads upon assembly of  23   a  and  23   b  therefore securing the attachment of arm right  23   a  to arm left  23   b.    
   As shown in  FIG. 4  the lower edges of arm right  23   a , and arm left  23   b  are irregularly shaped such that when joined to produce arm assembly  40  create two circular openings  75  and  76  that are joined by a serpentine shaped slot  77 . This arrangement allows the user to temporarily house a portion of the power and signal cables that accompany a typical video display unit. 
   As shown in  FIG. 5 , arms  23   a  and  23   b  are generally hollow in design and made from any molded material with the appropriate structural strength. Arm right  23   a  and arm left  23   b  are generally shaped as a channel with a rectilinear cross section throughout a rearward portion  69  and a tapering, generally semicircular cross section through a forward portion  70  terminating with an attached hemisphere  93 . Located near the midpoint of the arm is an oblong through slot  67  whose axis is generally perpendicular to the longitudinal axis of the arm and flanked on each side by walls  73  and  74 . Wall  73  has a semicircular notch  94 . 
   Rectangular through slot  68  aligns generally parallel with the longitudinal axis of the arm. Slot  68  is enclosed by rib  103 . Through the walls at the ends of slot  68  are semicircular notches  105  and  106  whose axis are aligned with the axis of notch  94 . At the rearmost portion of rectangular slot  68  is wall  97  that is perpendicular to the axis of slot  68 . 
   Arm rearward portion  69  terminates with offset area  71  that supports an externally protruding hollow cylindrical shape that creates arm axle  72  of specific diameter and length allowing it to extend through hole  95  and be captured in channel  24 . Several additional ribs  81  add structural strength and stability. 
   A wall  83  offset some distance from a lower edge of arm right  23   a  and arm left  23   b  and encompassing an irregular edge shape  66  extends from wall  74  forward past the irregular shape  66  and terminates at the lower edge of the arm. This creates a cavity  84  to accept temporarily stored video power and signal cords. 
   A moveable fulcrum  26  is generally a cubic shape of such dimension to allow it to be loosely captured by slot  68  and its surrounding rib  103 . From the sides of the cubic shape, extending outwardly are two cylindrical shapes forming axles  78  &amp;  79  of such diameter and length that they extend into and are loosely captured by channel  21  (FIG.  2 ). Through the centerline of the cubic shape and perpendicular to the axis of axles  78  &amp;  79  is a threaded hole  80  (FIG.  3 ). 
   A hand wheel  92  is rigidly attached to a threaded shaft  25 . Shaft  25  is terminated in a flat end  82  and has threads that are equal in size to threaded hole  80  and of such a diameter to allow it to be loosely captured in the semicircular notches  94 ,  105 , and  106  ( FIG. 5 ) upon assembly. Wheel  92  has a protruding hub surface  96  ( FIG. 3 ) such that the distance from the end of shaft  82  ( FIG. 3 ) to hub surface  96  is loosely captured between walls  74  and  97  (FIG.  5 ). The outside diameter and thickness of wheel  24  are such that it protrudes through the oblong arm slot  67  without interference. 
   As shown in  FIG. 6  a ball and socket friction producing arrangement  50  including a mounting plate  39  is assembled to encompass spherical shape  93 . The ball and socket arrangement includes two identical ball clamps  34   a , and  34   b  that include a spherical pocket  83  whose inside diameter matches that of hemisphere  93  and whose centerline lies some small distance off of flat surface  107 , such that as clamps  34   a  and  34   b  are assembled to encompass hemispheres  93 , surfaces  107  can not contact each other. Clamps  34   a  and  34   b  include a cylindrical boss  85  that contains a counter bored through hole  86  positioned such that the counter bore extends to surface  107 . Also included in the ball clamp is an oblong depression  111  of such dimension to accept double threaded plate  36 , compressible pad  35 , and to allow the heads of clamping screws  33   a  and  33   b  to be recessed into the overall outline of clamp  34   a . Clamps  34   a  and  34   b  incorporate two through holes  98  of such dimension to accept screws  33   a  and  33   b.    
   The mounting plate  39  as envisioned is a square plate with 4 mounting holes  108  dimensioned in such a way to accept a standard mounting geometry supplied by a majority of video display manufacturers. Formed from the plate are ears  88  and  89 . Through each ear is a hole  90  and  91  of such diameter to allow extended spring pins  37   a  and  37   b  to pass through the holes. The distance between the ears is such that it closely approximates the assembled overall length of the cylindrical bosses  85 . 
   Enclosed in the counterbored holes upon assembly is a compressed spring  38  and two headed pins  37   a  and  37   b  that are of such dimension that their heads  87  are loosely contained in the counter bored portion of hole  86  but they can not pass through counterbored hole  86 . The pins are of such length as to allow them to extend outwardly through holes  86  and through holes  90  and  91  in ears  88  and  89  of mounting plate  39  therefore axially constraining plate  39  to ball and socket friction producing arrangement. 
   DESCRIPTION OF OPERATION 
   In the preferred embodiment of the load support mechanism, the anchoring arrangement  10  is connected to a desk or work surface edge overhang by manipulation of members  14 ,  15  and  16  to apply a clamping force from the underside of the desk or surface. With the anchoring arrangement connected to the desk, the user is presented with a hollow vertical cylinder  13  into which he can insert the remaining assembly consisting of the housing assembly  20 , which contains the load counterbalancing arrangement  30 , arm assembly  40 , and the ball and socket friction producing arrangement  50 . With the assembly mounted as described, the arm assembly  40  will be forced by counterbalancing assembly  30  upwards such that the longitudinal axis of the arm makes an angle of approximately 45 degrees with the desk surface. This is due to the gas spring&#39;s normal position of full extension. In this position the outwardly projecting cylindrical axles  78  &amp;  79  on arm right  22   a  and arm left  23   b  would be positioned at or near the lowermost limit of the vertical channel  24  and the adjustable fulcrum  26  and its axles  78  and  79  would be positioned at or near the rearmost position of the horizontal pocket  21 . 
   The user can now remove the mounting plate  39  from the ball clamps  34   a  and  34   b  by depressing both pins  37   a  and  37   b  together, further compressing spring  38 . With the mounting plate  39  free from the assembly, it can be mounted to the load  100 , in this case a video display by use of the standard threaded fasteners arrangement provided by the display manufacturers. The video display with its attached mounting plate  39  can now be attached to the ball clamp arrangement by compressing pins  37   a  and  37   b  and releasing them to extend through the holes  90  and  91  in ears  88  and  89  completing the installation. At this time the arm assembly  40  may or may not be in a horizontal position. The user can move the arm into a nearly horizontal position by applying an upward or downward force, whichever is appropriate. While holding the unit in this position, the user can adjust the counterbalancing force by simply rotating the hand wheel  92  either clockwise to increase or counter clockwise to reduce the counterbalancing forces on the load. This adjustment is easily accomplished by hand without the use of tools, such as wrenches, etc. because the user is not required to add or subtract additional energy into the gas spring  27 . The user&#39;s adjustment moves the fulcrum  26  either toward the load  100  and away from the gas spring, or toward the gas spring  27  and away from the load  100 . 
   It can be seen by one skilled in the art that a relatively small movement in the position of the fulcrum  26  has a significant impact on the counterbalancing force due to the fact that as the fulcrum  26  is moved away from the gas spring  27  it not only increases the counterbalancing moment produced by the gas spring  27 , but it also decreases the moment produced by the cantilevered load  100 . Since this is the case, it can be seen that this position adjustable load support mechanism allows for a wide range of loads that can be counter balanced by the same energy storage device (in this case gas spring  27 ). In addition, since all of the moment-producing force vectors from the load are gravity produced, and therefore are always acting vertically, and the preferred embodiment of this system has the counterbalancing force from the gas spring  27  constrained in a vertical position due to vertical channel  24  throughout the loads range of motion, it can be seen that the generated load moments and counterbalancing moments remain in a proportional relationship. This relationship is not affected by the angle of the arm, because the position of the fulcrum  26  automatically moves horizontally as the load is moved vertically therefore allowing a larger range of motion to be obtained while still producing a useable counterbalancing force. 
   With the counterbalancing force adjusted properly for the individual load  100 , the user can easily raise or lower the load  100  by applying a force on the load  100 . This amount of force is very small because it only has to overcome the inherent internal friction in the gas spring, and the load will remain in that position when the force is removed. The horizontal motion is accomplished by rotating the load  100 , the arm assembly, and the housing assembly  20  about axis  46 , and the axis created by pins  37   a , and  37   b . The tilt of the load about a horizontal axis can be accomplished by rotating the pretensioned ball and socket friction producing arrangement about the centerline of the ball and socket joint. 
   The load in this improved mechanism is supported by a generally cantilevered arm arrangement. In order for the load to be counter balanced such that it will remain in its required position, the moment generated by the gas spring must be equal to the moment generated by the load and its distance from the fulcrum. The force generated by the load is due to gravity, therefore, it always acts vertically, and since the force from the gas spring is constrained by the vertical channel  24  it also acts vertically. Since these forces remain parallel, the moment created by each force varies as a function of its distance from the fulcrum multiplied by the cosine of the angle that each portion of the arm makes with a horizontal plane. These moments will remain in perfect balance as long as the center of gravity of the load, the fulcrum and the connection point of the gas spring to the arm all lie on the same axis, as shown in  FIG. 10   a.    
   A graphic representation of this constant force required by the gas spring is shown in  FIG. 9   a , by horizontal line # 1 . In this perfect condition of balance, any additional force or change in the load will change the vertical position of he load, which is not a useful condition for most applications, as some degree of position stability is required. In all energy storage devices however, including typical gas springs, the output forces are not constant and there is some amount of inherent friction. Line # 2  represents a typical force vs. displacement curve produced by the non linear gas spring output, as it articulates. A graphical representation of the spring output, which includes the inherent friction, produces Line # 3 . By connecting the ends of these lines, we create a parallelogram of useable hysterisis in the diagram. Due to the design of the internal components of gas springs, both the amount of force variation (represented by the incline of lines # 2  and # 3 ) and internal friction, represented by the vertical distance between lines # 2  and # 3 ) can be adjusted by the manufacturer. It can be seen that in any position where line # 1  (the required spring force) is enclosed by the hysterisis parallelogram, a balanced condition occurs. In order to reposition the load, an additional force of such magnitude to overcome the friction must be applied as shown by lines a and b. When the user adjusts the counterbalancing forces, by moving the position of the fulcrum, he equalizes the moments produced by the gas spring and the load. Graphically, this adjustment determines the vertical position of line # 1 . It can be seen that the margin for error in adjusting the counter balance can be relatively small, since the entire length of line # 1  must reside inside the parallelogram. It can also be seen from line # 4  that the mechanism can be adjusted and counterbalanced in several positions, yet it may depart from the counter balance condition at some other positions, as shown by section “c” of line # 4 , which lies outside the parallelogram. 
   The improved mechanism as shown in  FIG. 10   b , shows an arrangement where the center of gravity of the load, (represented by the hemispheres  66 ) is not aligned with the axis line connecting the fulcrum and the point where the gas spring connects to the arm. In this configuration, the hemispheres are offset above the axis by some predetermined angle ‘x’. 
     FIG. 9   b  is a representation of the improved mechanism including the previously described angle “x”. With the addition of this angle, the relationship of the cosine of the angles as previously described, are only proportional at one position. Graphically displayed ( FIG. 9   b ), this angle creates a condition where the forces required from the gas spring to balance the load (line # 5 ) are not constant as  FIG. 9   a  (line # 1 ). Therefore the graphical representation more closely matches the output of the gas spring (line # 2 ). One of the advantages is that the internal friction in the gas spring can be less, and the corresponding forces a′ and b′, that are required to move the load are generally smaller. It can be seen that the improved design creates a much preferred counterbalancing moment due to its ability to continuously adjust the moment generated by the gas spring to closely match that generated by the load as it is repositioned. 
     FIG. 9   c  illustrates an alternative arrangement for the present invention in which the position of the gas spring and the fulcrum are reversed. The gas spring connection point is constrained to move in a horizontal channel or other type of constraint. 
   DETAILED DESCRIPTION OF AN ALTERNATIVE EMBODIMENT 
   There are occasions when due to existing furniture configurations it would be advantageous to be able to anchor the system to a wall or office panel system. There are other occasions where anchoring the system in an inverted position would also be helpful in space conservation, etc. With the use of a wall mounted or bracketed anchoring arrangement  60 , both the previously described preferred embodiment, or this alternative embodiment can be used. Since it is evident to one skilled in the art to envision the wall anchoring of the preferred embodiment it will not be described. 
   An important alternative embodiment of the system is shown in FIG.  7 . The overall assembly of the ball and socket friction producing arrangement  50  and the arm assembly  40  are as described in the preferred embodiment. In this alternative embodiment the housing assembly  20  and gas spring  27  are inverted. The previously described strap  28  and nut  29  are eliminated. Gas spring rod end clevis  56  is attached to the rearward ends of arm right  23   a  and arm left  23   b  by the addition of cross pin  99 . Pin  99  has a diameter such that it is loosely controlled by the gas spring mounting hole  57  and the internal diameter of arm axle  72  on arm  23   a  and  23   b . On the now upper end of gas spring  27 , threaded stud  58  is supported and controlled by semicircular notch  44 . 
   In  FIG. 7  a typical office panel bracketed anchoring system  60  is shown. It consists of a vertical hollow cylinder  101  with an upper rim  109  connected to any number of notched flanges  104  that would be acceptable to a typical office panel configuration. The original cable support component  17  can be used as required. A circular split ring  102  with an “L” shaped cross section is used to lock the vertical position of the housing assembly  20  upon installation. FIG.  8 . To install the inverted system, the bracketed anchoring arrangement  60  is rigidly attached to a vertical surface. The housing assembly  20  is then inserted upwardly through the cylinder  101  until the circular groove  45  is above the top edge of cylinder  101 . Split ring  102  is expanded and forced into groove  45 , in such a way as to allow the vertical portion of the inverted “L” shape to be inserted inside the cylinder  101 . As the housing assembly  20  and ring  102  are lowered into position the flange portion of the ring contacts the upper rim  109  of the cylinder  101  and prevents the assembly  20  from further downward motion, without disrupting the ability of the assembly to rotate about axis  46 . 
   Since the normal position of the gas spring  27  is extended it can be seen that arm assembly  40  will be forced to an upward position with respect to a desk surface in the same way as it is in the preferred embodiment. All of the user adjustability is retained as well as all of the system capability and functions. 
   Thus the reader will see that the position adjustable load support mechanism&#39;s of the present invention produce a highly functional yet economical device that provides the user with many advantages over the prior art. 
   While my above description contains many details these should not be construed as limitations on the scope of the invention but rather as an exemplification of one preferred embodiment thereof. Many other variations are possible. For example the gas spring energy storage device as stated could be replaced by a more conventional mechanical tension compression or constant force spring if the spring is accompanied by some type of friction producing device to create the necessary force vs. displacement hysteresis. Also the described embodiments illustrate a pair of linear perpendicular motion controlling channels in the housing components. There may be applications where these channels are neither linear nor perpendicular to each other nor parallel with the axis of the energy storage device. These variations may be made in order to maximize the effectiveness of the mechanism or as the result of a specialized design. Additionally the shape and size of the individual components could be varied to maximize their effectiveness aesthetically economically or functionally. 
   Accordingly the scope of the invention should be determined not by the embodiments illustrated but by the appended claims and their legal equivalents. 
   List of Reference Numbers 
   NO. Component
           9  Slot     10  Anchoring arrangement     11  Channel flanged surface     12  Channel shaped member     13  Hollow cylinder     14  Threadable member     15  Disk shaped pad     16  Clamping handle     17  Cable support Ring     18  Large through hole     19  Small through hole     20  Housing assembly     21  Horizontal channel     22   a . Housing Rt.  b . Housing Left     23   a . Arm Rt.  b . Arm Left.     24  Vertical channel     25  Threaded shaft     26  Fulcrum     27  Gas spring     28  Strap     29  Nut     30  Load ct&#39;bal arrangement     31   a. b. c . Screws     32   a. b. c. d. e . Screws     33   a. b . Clamping screws     34   a. b . Ball clamp     35  Compressible pad     36  Double threaded plate     37   a. b . Pins     38  Spring     39  Mounting plate     40  Arm assembly     41  Upper portion of  40       42  Lower portion of  40       43  Semicircular rib     44  Semicircular notch     45  Semicircular groove     46  Housing CL axis     47  Slot     48  Rib     49  Notch     50  Ball &amp; Socket friction producing arrangement     51   a. b . Assembly post     52   a. b . Assembly post     53   a. b . Assembly post     54  Offset edge     55  Vert. and Hor. ribs     56  Rod end clevis     57  Mounting hole     58  Threaded stud     59  Strap hole     60  Bracketed anchoring arrangement     61   a. b . Assembly post     62   a. b . Assembly post     63   a. b . Assembly post     64   a. b . Assembly post     65   a. b . Assembly post     66  Cable storage area     67  Slot     68  Slot     69  Arm rearward     70  Arm forward     71  Offset area     72  Arm axle     73  Wall     74  Wall     75  Circular opening     76  Circular opening     77  Serpentine slot     78  Axle     79  Axle     80  Threaded hole     81  Ribs     82  End of shaft     83  Spherical pocket     84  Cable support cavity     85  Cylindrical boss     86  Counter bored hole     87  Pin head     88  Ear     89  Ear     90  Hole     91  Hole     92  Hand wheel     93  Hemisphere     94  Notch     95  Strap hole     96  Protruding hub     97  Wall     98  Screw hole     99  Cross pin     100  Load     101  Hollow cylinder     102  Split ring     103  Rib     104  Notched flange     105  Notch     106  Notch     107  Flat surface     108  Mounting holes     109  Cylinder upper rim     110  Closed end wall     111  Oblong depression