Patent Publication Number: US-2005121578-A1

Title: Locking joint for support arm

Description:
This application claims priority to U.S. Provisional Application No. 60/498,471 filed Aug. 27, 2003 which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      This application relates to devices and methods for moveably supporting equipment. Specifically, but not by way of limitation, this application relates to devices and methods for supporting display screens such as flat panel display screens for use with personal computers.  
     BACKGROUND  
      In many fields, it is useful to support equipment in such a way to make the position of the equipment adjustable. In particular, flat panel display screens for personal computers are gaining popularity with consumers. It is desirable for users of personal computers to be able to position their computer screens, such as flat panel screens in orientations that are ergonomically correct.  
      Although embodiments of the present invention can be used with several different adjustment joints, an elevation joint is used as an example. An elevation adjustment is useful to provide flexibility for users of different heights. One common elevation adjustment includes an arm configuration with a joint between two arm portions. A user can extend a distal arm portion upwards or downwards by rotating the distal arm in relation to a base arm portion about an elevation joint.  
      It is inconvenient for the user if the equipment, such as the flat panel display, does not stay in the intended position. Unwanted motion can be caused by the elevation joint being too loose, with the equipment moving under its own weight. Unwanted motion can also be caused by inadvertent bumping of the arm or supported equipment. Further, if the elevation joint moves an excessive amount, the supported equipment, such as the flat panel display, may become damaged by hitting a surface such as a desktop.  
      What is needed is an improved support arm that provides adjustability. What is also needed is an improved support arm that reduces unwanted motion of adjustment joints such as elevation joints. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a support arm according to an embodiment of the invention.  
       FIG. 2  shows an exploded view of a joint according to an embodiment of the invention.  
       FIG. 3  shows another exploded view of a joint according to an embodiment of the invention.  
       FIG. 4  shows an engaging device according to an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION  
      In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical changes, etc. may be made without departing from the scope of the present invention. In the following description, unless otherwise provided, the term “locked” is defined for joint motion as being fixed in a position until an actuator device releases a locked condition. This is in contrast to detent configurations, or spring biased conditions that require additional force to overcome a barrier to motion of a joint.  
       FIG. 1  shows a support arm  100  according to an embodiment of the invention. In one embodiment, selected components of the support arm are fabricated from cast aluminum. Other materials such as steel, polymers, etc. are also within the scope of the invention. Likewise, other fabrication methods such as forging, CNC machining, etc. are also within the scope of the invention.  
      The support arm  100  includes a first arm portion  110  and a second arm portion  120 . In one embodiment, the first arm portion  110  includes a base portion  112  and an upper portion  114 . In one embodiment, the base portion  112  and the upper portion  114  are coupled together mechanically. In one embodiment, the base portion  112  and the upper portion  114  are integrally formed.  
      The second arm portion  120  includes a main arm  122 . In one embodiment, other adjustment components  150  such as rotation joints are also included with the second arm portion  120 . The embodiment of  FIG. 1  includes a first axis joint  152 , a second axis joint  154 , and a third axis joint  156 .  
      An equipment support  140  is further shown in  FIG. 1  with a number of attachment holes  142 . In one embodiment, the equipment support  140  is adapted to mount a flat panel display screen such as used with personal computers, although the invention is not so limited. In another option, the equipment support  140  is integral to the display screen.  
      An elevation joint  130  is shown between the first arm portion  110  and the second arm portion  120 . When actuated, the elevation joint  130  allows a user to adjust a height of the equipment support  140 . A number of actuating pins  162  are further shown in  FIG. 1 . The actuating pins will be discussed in more detail below. In one embodiment, a cover  164  is included and is attached over the actuating pins  162  as shown by the arrow in  FIG. 1 . Optionally, the cover  164  includes recesses  161  sized and shaped to receive the pins  162 , as shown in  FIG. 3 . Although in one embodiment, the cover  164  is used to actuate the actuating pins  162 , other configurations such as mechanical linkages, buttons, etc. are also acceptable to actuate the actuating pins  162 .  
       FIG. 2  shows details of components between the first arm portion  110  and the second arm portion  120 . A first engaging feature  116  is shown on the upper portion  114  of the first arm portion  110 . In one embodiment, the first engaging feature includes a number of teeth. In one embodiment, the number of teeth are formed in a female configuration to accept an engaging device  170 . Although a number of teeth are shown in  FIG. 2 , one of ordinary skill in the art, having the benefit of the present disclosure, will recognize that several geometries of engaging features are possible. For example, square features, triangular, other polygons, etc. In one embodiment, a number of teeth are used to provide a high number of possible rotational selections within the first engaging feature  116 .  
      A first friction surface  118  is also shown on the upper portion  114  of the first arm portion  110 . In one embodiment, the first friction surface  118  is adapted to mate with a friction insert such as a friction washer  180 . Although a washer configuration is shown, other geometries of inserts are possible to provide frictional resistance between surfaces in the elevation joint  130 .  
      An engaging device  170  is further shown in  FIG. 2  that is adapted to engage the first engaging feature  116  of the first arm  110 . As described above, in one embodiment, a toothed configuration, such as a gear is used to provide a high number of possible rotational selections.  
      A number of features  115  such as pockets are further shown as part of the first arm portion  110 . In one embodiment, a number of compression springs  117  ( FIG. 3 ) are placed within the features  115 . The number of compression springs  117  are adapted to urge the engaging device  170  along direction  172 . Although the compression springs  117  are used in one embodiment, other urging devices, such as other spring varieties, elastomer inserts, etc. are also possible within the scope of the invention.  
      An actuating device  160  is also shown in  FIG. 2 . In one embodiment, the actuating device includes a number of actuating pins  162 . In operation, the actuating device bears against the engaging device  170 . When the actuating pins  162  are pressed, the engaging device  170  is forced farther into the first engaging feature  116  against the urging force of components such as compression springs discussed above. Although three actuating pins are shown, other numbers of actuating pins are also within the scope of the invention. Likewise, components other than pins, such as linkages, etc. that operate to displace the engaging device  170  are also within the scope of the invention.  
       FIG. 3  shows another view of components between the first arm portion  110  and the second arm portion  120 . A joint axis  132  of the elevation joint  130  ( FIG. 1 ) is shown. A second engaging feature  126  is shown on a joint end  124  of the main arm  122 . Similar to the first engaging feature, in one embodiment, the second engaging feature  126  includes a number of teeth. In one embodiment, the number of teeth are formed in a female configuration to accept the engaging device  170 . Although a number of teeth are shown in  FIG. 3 , one of ordinary skill in the art, having the benefit of the present disclosure, will recognize that several geometries of engaging features are possible. For example, square features, triangular, other polygons, etc. In one embodiment, a number of teeth are used to provide a high number of possible rotational selections within the second engaging feature  126 .  
      A second friction surface  128  is also shown in  FIG. 3 . In one embodiment, a friction washer  180  engages both the first friction surface  118  and the second friction surface  128  to provide smooth and controlled movement between the first arm portion  110  and the second arm portion  120 . In one embodiment, the friction washer  180  includes a polymer friction washer. In one embodiment, the friction washer  180  includes an ultra high molecular weight polyethylene washer. As discussed above, although a washer is shown, other shapes of material that provide a friction function are within the scope of the invention.  
      In one embodiment, the first arm portion  110  and the second arm portion  120  are secured together using a fastener  131  that is inserted through openings along the axis  132  as shown in  FIG. 3 . Several options are possible for the fastener  131 , including a nut and bolt, a rivet, or other mechanical fastening systems. Because the joint  130  as described in embodiments above is selectively locked in place by the engaging device  170 , a tension of the fastener  131  is less critical than in non-locking designs. A fastener only needs to provide adequate tension for smooth operation between the first friction surface  118  and the second friction surface  128 . Use of the friction washer  180  further provides some degree of leeway in acceptable fastener tension during manufacturing. In one embodiment, use of a rivet as a fastener is possible because of the less critical fastener tension. One of ordinary skill in the art, having the benefit of the present disclosure will recognize that use of a rivet is less expensive for manufacturing than use of a nut and bolt. A second cover  133  is provided in one option to at least partially cover a portion of the fastener  131 .  
       FIG. 4  shows one embodiment of an engaging device  170 . As discussed above, in one embodiment, the engaging device  170  includes a toothed gear. In one embodiment, each tooth  174  includes an asymmetric profile. As shown in  FIG. 4 , in one embodiment, one side of the teeth  174  have a first width  176  and the other side of the teeth  174  have a second, thinner width  178 . In one embodiment, the difference in widths provides a taper to the teeth  174 . Although a taper is described in the context of teeth, one of ordinary skill in the art, having the benefit of the present disclosure, will recognize that a taper can be used on other geometries of engaging devices. In one embodiment, the engaging device  170  is oriented so that the thinner width  178  faces the second engaging feature  126 .  
      In operation, the elevation joint  130  includes two conditions, locked and unlocked. The condition of the elevation joint  130  is determined by a position of the engaging device  170 . The engaging device  170  is allowed to move within a range of motion within the elevation joint  130 . In one embodiment, the engaging device is further biased using compression springs as described above to be normally in a selected portion of the range of motion.  
      In one embodiment, in the normal biased portion of the range of motion the elevation joint is locked. In one embodiment, in the normal biased portion of the range of motion, the engaging device  170  engages both the first engaging feature  116  and the second engaging feature  126 .  
      When the actuating pins  162  are pushed, the actuating device  160  displaces the engaging device  170  into the first engaging feature  116  to a second location in the range of motion so that only the first engaging feature  116  is engaged by the engaging device  170 . When the engaging device  170  is in the second location, the elevation joint  130  is in the unlocked state, and the second arm portion  120  is therefore free to rotate about the joint axis  132 .  
      When the actuating pins are released, compression springs as described above urge the engaging device  170  back so that the elevation joint is in a normally locked state. In one embodiment, the cover  164  is used to depress the actuating pins  162  at the same time. In one embodiment, the cover  164  is attached to the actuating pins using a suitable attachment method such as adhesive, mechanical attachment, etc. As discussed above, other configurations such as mechanical linkages, buttons, etc. are also acceptable to depress the actuating pins  162 .  
      In one embodiment, the taper as described above, and shown in  FIG. 4 , enhances engagement of the engaging device  170  into the second engaging feature  126  to put the elevation joint  130  back into the locked state. The taper reduces the probability of an alignment error between the engaging device  170  and the second engaging feature  126 . In one embodiment, because the engaging device  170  is always at least partially engaged in the first engaging feature  116 , there is no alignment error issue between the engaging device  170  and the first engaging feature  116 .  
     Conclusion  
      Using embodiments described above, a number of advantages are realized. One advantage includes a simple, joint device that provides selective adjustment to a user. In one example, embodiments described above provide an adjustable elevation joint. Another advantage of embodiments described above includes a selective locking joint that securely locks a position of a joint such as an elevation joint, once a position is selected. A locking joint provides security against unwanted movement of a joint. Another advantage of embodiments described above includes a simple design that is inexpensive to manufacture. In selected embodiments, features such as first and second engaging features are integrally cast into components. Integral forming reduces a number of parts required for manufacture, which in turn reduces cost. As discussed above, a further cost advantage is obtained in selected embodiments though the use of fasteners such as rivets in place of nuts and bolts.  
      Although selected advantages are detailed above, the list is not intended to be exhaustive. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention includes any other applications in which the above structures and fabrication methods are used.