Abstract:
An equipoise armature comprises a parallelogram with a bridge piece positioned at a centroid based on the weight of a supported article and counterweight, to enable pivotal mounting of the armature to the bridge piece. The armature is adapted to carry an article, such as a lamp, a magnifier, a display, etc., for positional movement of the article.

Description:
BACKGROUND 
     This disclosure relates to armatures, and more particularly to an equipoise armature suitable for many uses. 
       FIG. 1  illustrates a simple balance beam or lever having symmetrical loading of substantially equal weights at each end of the lever, and the fulcrum at the center position of the beam. If the loading at the ends is different, the fulcrum point is moved to keep the beam in balance, as shown in  FIG. 2 . 
     If using these concepts for supporting an item, such as a lamp, it is advantageous to employ a “Z” beam, where a pivot is added mid-portion of the beam at either side of the fulcrum, to allow extension/contraction positioning of the ends of beam(s), as illustrated in  FIG. 3 , with equal loading at the ends, or  FIG. 4 , with unequal loading. 
       FIG. 12  is a schematic representation of the device disclosed in U.S. Pat. No. 3,219,303, which 1) is a “pantograph” configuration (with two perpendicular sides extending into arms, and 2) has its balance point on the parallelogram, as opposed to an interior point “C”. With the balance point on the edge corner of the parallelogram, it creates an imbalance when the device out of level. In level position, the balance point “C” is centered over the fulcrum centerline. But, as the device is rotated out of level (down and around) this results in more and more of the device being “all on one side” of the fulcrum centerline: lopsided (see: “A” Device Rotated). The device here will continue to rotate (B) and invert into an upside down hanging equilibrium. Indeed, the built device based on this patent requires a friction screw at the balance point to provide resistance to this overturning tendency. Extending perpendicular parallelogram sides for arms, instead of opposing sides, further exacerbates this lopsidedness. 
       FIGS. 14 and 15  are diagrams based on the disclosure of U.S. Pat. No. 6,991,199, which is based on a “bent parallelogram” with what looks to be a bridge segment subdividing the parallelogram. On inspection it is observed that the bridge segment “A” is fixed on the table base, and is not free to rotate. Nor is it weight counterbalanced, but spring balanced.  FIG. 14  shows the device in a stowed position and  FIG. 15  adds the configuration in the extended position. This device is a two position device (stowed, extended), instead of an infinite position device. Its lower portions are bent to create a mechanical advantage for its two positions. These limitations (fixed bridge element; two position limit; and spring counterbalance) are part of what makes this device less desirable. 
     Whereas the U.S. Pat. No. 6,991,199 patent document represents the “bent parallelogram” as elemental, we observe that one of the corners of the parallelogram below the bridge can be removed and not affect the levering of the parallelogram by the lever arm below the bridge element “A”: the remaining arm with spring counterbalance connection will still lever the device from stowed to extended. What looks to be an important integral part of the parallelogram is, in fact, redundant. This redundancy is part of what makes this device less desirable. 
     What would be desirable would be to have an armature that allows an object, such as a lamp, magnifier, display, or the like to be re-positionably supported in an efficient manner, remaining balanced whether at a horizontal angle, a vertical angle, in an open position, or in a closed position. 
     SUMMARY 
     In accordance with the disclosure, an armature is constructed as a lever beam comprised of a parallelogram with opposing extensions of two of its opposite sides, and a bridge-piece mid parallelogram to provide a physical location (at the device centroid) for a lever pivot point. 
     Accordingly, it is an advantage of the present disclosure to provide an improved armature. 
     It is a further advantage of the present disclosure to provide an improved armature for supporting objects. 
     It is yet another advantage of the present disclosure to provide an improved support arm for carrying a lamp, a display, a microphone, a screen, or other uses 
     The subject matter of the present technology is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and embodiments thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a simple balance beam/lever with symmetrical loading; 
         FIG. 2  is a diagram of a simple balance beam/lever with asymmetrical loading; 
         FIG. 3  is a diagram of a “Z” beam/lever with symmetrical loading; 
         FIG. 4  is a diagram of a “Z” beam/lever with asymmetrical loading; 
         FIG. 5  is a schematic diagram of an equipoise armature with imaginary theoretical center indicated; 
         FIG. 6  is a schematic diagram of an equipoise armature with an added bridge, with equal weights at the ends of the arms; 
         FIG. 7  is a schematic diagram of an equipoise armature with an added bridge, with unequal weights at the ends of the arms, wherein the bridge position is moved; 
         FIGS. 8-10  are illustrations of the equipoise armature used as a lamp armature; 
         FIG. 11  is a physical model and a line schematic view of the device of the present disclosure; 
         FIG. 12  is a view of a device in accordance with U.S. Pat. No. 3,219,303; 
         FIG. 13  is an illustration of the presently disclosed device as a lamp support; 
         FIG. 14  is a view of the device of U.S. Pat. No. 6,991,199 in a stowed position; 
         FIG. 15  is a view of the device of U.S. Pat. No. 6,991,199 in an extended position; 
         FIG. 16  is a hypothetical illustration of a configuration of the present disclosure altered to match that of the U.S. Pat. No. 6,991,199 device; and 
         FIGS. 17 and 18  are illustrations of extending the “bent parallelogram” device of U.S. Pat. No. 6,991,199 below an “Angle A” to illustrate contrast with the presently disclosed device. 
     
    
    
     DETAILED DESCRIPTION 
     The system according to a preferred embodiment of the present disclosure comprises an armature that employs a parallelogram lever beam having opposing extensions of two of its opposite sides. A bridge-piece connects two of the parallel legs at the centroid of the configuration (when considering the relative weights of the objects carried at the ends of the extension) to provide a pivot point. In use, the system is in equilibrium, regardless of the rotation position about the pivot point. 
     Referring now to  FIG. 5 , the armature  10  is constructed as a “Z” Beam parallelogram (parallel sides  12 ,  14  and  16 ,  18  with extensions provided to extend sides  16  and  18  outwardly. A pivot point  20  is provided at the beam centroid (the center of mass of the beam. In  FIG. 1 , a force  22  is illustrated at the left end of arm  18 , balanced by force  24  at the right end of arm  16 . 
     Considering  FIG. 6 , a schematic diagram of an equipoise armature with an added bridge with equal weights  22 ′,  24 ′ at each end, a bridge segment  26  is pivotally connects sides  12 ,  14 , to provide the connection point (suitably at the center of the bridge segment) to the pivot. The dashed lines in  FIG. 1  illustrate the movement action of the equipoise armature when the ends of arms  16 ,  18  are moved closer together (whereas the solid lines show the configuration when the arm ends are moved farther apart). 
       FIG. 7 , a further schematic diagram of an equipoise armature with an added bridge, illustrates the case of with unequal weights  28 ,  30  at the ends of the arms, wherein the bridge position is moved towards the left in  FIG. 7  (towards the direction of the weight  28 ,  30  that is greater in weight). The dashed lines illustrate the movement of the armature when the ends of arms  16 ,  18  are brought closer together. Movement of the bridge allows compensation for the weight differential between the two end weights. 
       FIGS. 8-10  are perspective view illustrations of the equipoise armature used as a lamp armature, wherein in  FIG. 8 , the armature is retracted to substantially the position of greatest retraction. In  FIG. 9 , the armature is extended a substantial amount, while in  FIG. 10 , the armature is drawn-out to its maximum extent. 
     In the lamp armature configuration shown, the extension arms  32 ,  34  (corresponding to arms  18 ,  16  of  FIG. 5 ) are of unequal length and a counter weight  36  is positioned at the outer end of shorter arm  34 , to counter balance the weight of lamp  38 , positioned at the far end of arm  32 . Central arms  40 ,  42  are substantially the same length in this configuration. Arms  40  and  40  are pivotally connected to arms  32 ,  34  in spaced arrangement, via pivot members  44 . 
     Bridge  46  is connected at pivot points  48 ,  50  to each of central arms  40 ,  42 , and a mounting stand arm  52  is connected generally centrally of the bridge to allow pivoting of the entire assembly. The mounting stand arm is suitably rotationally mounted to base  54  to allow rotation of the lamp assembly as illustrated by arc  56 , whether by rotation of arm  52  relative to the base  54  or rotation of the base  54  relative to the surface on which the base sits. In operation, the longitudinal axis of the bridge remains parallel to the longitudinal axes of the extension arms. 
     In summary, referring to  FIG. 11 , a view of a physical model and line schematic of the configuration of a device in accordance with the present disclosure, the device has main parallelogram “A” inscribed with two smaller parallelograms B 1  and B 2 . This subdivision is result of addition of bridge-piece “C” which provides a center point “inside” the main parallelogram for balance on fulcrum. In addition, the main parallelogram extends two opposing sides, in opposition, into arms “D”: the whole forming a spiral. This spiral is what keeps the ends of the arms always the same relative each other across the balance point. The present device remains balanced at horizontal angle, vertical angle, open, or closed, providing an improvement over the art. 
     Referring to  FIG. 12 , a view of a device in accordance with U.S. Pat. No. 3,219,303, the device therein 1) is a “pantograph” configuration (with two perpendicular sides extending into arms), and 2) has its balance point on the parallelogram. With the balance point on the edge corner of the parallelogram, it creates an imbalance when the device is out of level. In level position, the balance point “C” is centered over the fulcrum centerline. But, as the device is rotated out of level (down and around) this results in more and more of the device being “all on one side” of the fulcrum centerline: lopsided (see: “A” Device Rotated). The device of this patent will continue to rotate (B) and invert into an upside down hanging equilibrium. Indeed, the built device based on this patent requires a friction screw at the balance point to provide resistance to this overturning tendency. Extending perpendicular parallelogram sides for arms, further exacerbates this lopsidedness. 
     Unlike the device of U.S. Pat. No. 3,219,303, which has extending perpendicular parallelogram sides for arms which exacerbate the lopsidedness of the device therein, the presently disclosed device has two opposing sides. Referring to  FIG. 13 , an illustration of the presently disclosed device, the present device always has equal parts (distances A and B) of its assembly on either side of the fulcrum centerline. Thus is superior as it has none of the overturning tendency of the device of U.S. Pat. No. 3,219,303. 
     Further, with reference to the U.S. Pat. No. 6,991,199 device, shown in  FIG. 14  in a stowed position, and  FIG. 15  in an extended position which shows the armature moving from a stowed to open position with spring length change, to make the configuration of the present disclosure match that of the U.S. Pat. No. 6,991,199 device, removing the same segment (A) of  FIG. 15  from device of the current disclosure (see  FIG. 16 ) results in the counterbalancing arm to flop away of its own accord, now having no connection, or influence, to the assembly&#39;s main parallelogram, rendering the device unworkable. Unlike the “Bent Parallelogram”, the device of the current disclosure has a non-subtractive assembly, each of its elements contributing to its more sophisticated, and superior, performance. 
     Further considering the present device in contrast to that of U.S. Pat. No. 6,991,199, with reference to  FIGS. 17 and 18 ,  FIG. 17  shows the possibility of extending the “bent parallelogram” device of U.S. Pat. No. 6,991,199 below “Angle A”, to be comparable in size and length to device of the present disclosure, with counterbalance spring still operable. This is a test illustration, which shows that the possibility that the “bent parallelogram” is not the same as present disclosed device&#39;s regular parallelogram. 
       FIG. 18  shows an attempt to use the “bent parallelogram” of U.S. Pat. No. 6,991,199 on the device of the present disclosure. This test shows that bending the parallelogram moves the device axis “B” away from the true balance center, or centroid, “C”. With the device axis moved off-centroid, the device becomes “lopsided”, rendering it less effective thus inferior as a result of incorporating the teaching of U.S. Pat. No. 6,991,199. 
     Therefore, the device in accordance with the present disclosure is seen as different and superior in respect to the prior art devices, including the following features: Spiral not pantograph; Center-balanced not edge-balanced; Subdivided-parallelogram that cannot be subtracted from as it can the one patent, Regular-parallelogram not bent-parallelogram; Balanced at all angles, not top-heavy in some; and Counter-weighted in infinite positions not counter-sprung in two positions. 
     The present device is markedly identifiable by its 1) main parallelogram subdivided by 2) a bridge-piece, and 3) its spiral armatures. 
     Accordingly, an equipoise armature is provided suitable for use as a lamp armature, display support, microphone stand, screen positioning device, lift or other uses. 
     While a preferred embodiment of the technology has been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the broader aspects. The appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the technology.