Support arm and method with variable counterbalance

Abstract

A support arm includes an arm having a proximal arm pivot joint that provides a range of elevational rotation of the arm. The arm further includes a distal component mount. The support arm further includes a biasing device adapted to provide an increasing force with increasing displacement. A flexible element is coupled between the biasing device and the arm with a linkage therebetween. At least a portion of the flexible element forms a segment between the arm and the linkage. The segment is at an angle relative to the arm, and the angle varies during rotation of the arm. An arm end location of the segment is fixed in relation to the arm during rotation of the arm. A linkage end location of the segment changes in relation to the pivot joint during rotation of the arm.

1 . A support arm, comprising: 
 an arm having a proximal arm pivot joint to provide a range of elevational rotation of the arm, and a distal component mount;    a biasing device sized and shaped to provide an increasing force with increasing displacement;    a flexible element coupled between the biasing device and the arm with a linkage between the arm and the biasing device wherein at least a portion of the flexible element forms a segment between the arm and the linkage and the segment is at an angle relative to the arm, wherein the angle varies during rotation of the arm; and    wherein an arm end location of the segment is fixed in relation to the arm during rotation of the arm, and a linkage end location of the segment change in relation to the pivot joint during rotation of the arm.    
   
   
       2 . The support arm of  claim 1 , wherein the linkage includes at least one pulley.  
   
   
       3 . The support arm of  claim 1 , wherein the arm includes a four bar linkage.  
   
   
       4 . The support arm of  claim 3 , wherein the four bar linkage includes a second arm sized and shaped to correspondingly rotate with the arm, and another portion of the flexible element is coupled to the second arm.  
   
   
       5 . The support arm of  claim 1 , wherein the flexible element includes a metal cable.  
   
   
       6 . The support arm of  claim 1 , wherein the biasing device includes a tension spring.  
   
   
       7 . The support arm of  claim 1 , wherein the biasing device includes a compression spring.  
   
   
       8 . The support arm of  claim 1 , wherein the angle of the segment changes during rotation of the arm and the angle of the segment adjusts a moment applied to the arm by the biasing device throughout the range of elevational rotation of the arm.  
   
   
       9 . The support arm of  claim 1 , wherein the biasing device is progressively displaced throughout the range of motion of the arm, and the angle of the segment changes at a higher rate at least when the arm rotates below horizontal to adjust a moment applied to the arm by the progressively displaced biasing device.  
   
   
       10 . The support arm of  claim 1 , further comprising an additional pulley coupled with the biasing device to double displacement of the flexible element in relation to displacement of the biasing device.  
   
   
       11 . A support arm, comprising: 
 a four bar parallelogram linkage arm having a proximal arm pivot end to provide a range of elevational rotation of the arm, and a distal component mount;    a spring coupled to an upper member of the four bar linkage parallelogram;    a flexible element coupled between a bottom member of the four bar parallelogram linkage arm and the spring with a pulley between the bottom member and the spring wherein at least a portion of the flexible element forms a segment between the bottom member and the pulley, and the segment is at an angle relative to the bottom member, wherein the angle varies during rotation of the arm; and    wherein an arm end of the segment is fixed in relation to the bottom member during rotation of the arm, and a tangent location of a pulley end of the segment changes in relation to the pivot end of the arm during rotation of the arm.    
   
   
       12 . The support arm of  claim 11 , wherein the flexible element includes a metal cable.  
   
   
       13 . The support arm of  claim 11 , wherein the arm end of the segment can be adjusted within a range of locations along the bottom member to a plurality of locations, wherein a selected location in the range remains fixed in relation to the bottom member during rotation of the arm.  
   
   
       14 . The support arm of  claim 11 , wherein the angle varies during rotation of the arm between around 90 and −90 degrees.  
   
   
       15 . The support arm of  claim 11 , further including an additional pulley coupled to the spring to double flexible element displacement in relation to spring displacement.  
   
   
       16 . The support arm of  claim 11 , wherein the spring includes a compression spring.  
   
   
       17 . The support arm of  claim 11 , wherein the spring is progressively displaced throughout the range of motion of the arm, and the angle of the segment changes at a higher rate at least when the arm rotates below horizontal to adjust a moment applied to the arm by the progressively displaced spring.  
   
   
       18 . A system, comprising: 
 a wheeled chassis;    a support arm coupled to the wheeled chassis, the support arm including: 
 an arm having a proximal arm pivot joint to provide a range of elevational rotation of the arm, and a distal component mount;  
 a spring;  
 a flexible element coupled between the arm and the spring with at least one pulley between the arm and the spring wherein at least a portion of the flexible element forms a segment between the arm and the at least one pulley, and the segment is at an angle relative to the arm, wherein the angle varies during rotation of the arm;  
 wherein an arm end of the segment is fixed in relation to the arm during rotation of the arm, and a tangent location of a pulley end of the segment changes in relation to the pivot end of the arm during rotation of the arm;  
   a display screen coupled to the distal component mount; and    a processor unit in communication with the display screen.    
   
   
       19 . The system of  claim 18 , wherein the arm includes a four bar linkage arm.  
   
   
       20 . The system of  claim 18 , wherein the spring includes a compression spring.  
   
   
       21 . The system of  claim 18 , further comprising an additional pulley coupled to the spring, and the additional pulley and the at least one pulley are adapted to double cable displacement in relation to spring displacement.  
   
   
       22 . The system of  claim 18 , wherein the display screen includes a flat panel computer monitor.  
   
   
       23 . The system of  claim 18 , wherein the processor unit is located adjacent to the wheeled chassis.  
   
   
       24 . A method for making a support arm comprising: 
 coupling a flexible element between a biasing device and a first member, and the first member includes a pivot joint, and the biasing device provides an increasing force with increasing displacement; and    moveably coupling a linkage along the flexible element, and the linkage is between the first member and the biasing device, and at least a portion of the flexible element forms a segment between the first member and the linkage and the segment is at an angle relative to the first member, wherein the angle varies during rotation of the first member, and an arm end location of the segment is fixed in relation to the first member during rotation, and a linkage end location of the segment changes in relation to the pivot joint during rotation.    
   
   
       25 . The method of  claim 24 , wherein moveably coupling the linkage along the flexible element includes moveably coupling at least one pulley along the flexible element.  
   
   
       26 . The method of  claim 25 , further comprising coupling the at least one pulley to a second member, wherein the second member is adapted to correspondingly move with the first member.  
   
   
       27 . The method of  claim 25 , further comprising coupling an additional pulley between the biasing device and the flexible element, and the additional pulley is moveably coupled to the flexible element.  
   
   
       28 . The method of  claim 24 , further comprising coupling another portion of the flexible element to a second member, wherein the second member is adapted to correspondingly move with the first member.  
   
   
       29 . The method of  claim 24 , further comprising coupling a portion of the biasing device to a second member, wherein the second member is adapted to correspondingly move with the first member.