US Patent 9291793 Apparatus for compact counter balance arms

In one embodiment of the invention, an apparatus is provided including a linkage and a balancing mechanism coupled to the linkage around a pivotal joint. The linkage couples to a support structure at a first end and support a weight applied to a second end. The balancing mechanism counter balances the weight applied to the second end of the linkage. As the linkage is deformed to vertically adjust the height of the weight with a different moment arm length, the balancing mechanism varies a cable path length to modify the compression of a spring and a tension in a cable to adjust the amount of counter balance force applied to the linkage.