Compact counter balanced arm

A compact counter balance link for a counter-balanced arm, the compact counter balance link comprising:

• a hollow housing with a cylindrical cavity having an open end and a closed end with a small opening;
• a first pivotal joint near the closed end of the hollow housing, the first pivotal joint configured to pivot the compact counter balance link with respect to another linkage, of the counter balance arm, coupled to the first pivotal joint;
• a second pivotal joint near the open end of the hollow housing, the second pivotal joint configured to pivot a load coupled to the second pivotal joint with respect to the compact counter balance link;
• a compression spring assembly inside the cavity of the hollow housing, the compression spring assembly including a coil spring configured to provide a counterbalance force in opposition to a weight of the load;
• one or more cables routed through the small opening of the closed end of the housing into a first end of the coil spring, and through a center of the coil spring, the one or more cables coupling to a second end of the coil spring, the one or more cables configured to compress the coil spring of the compression spring assembly in reaction to a downward pivot of the load thereby providing a counterbalance force in opposition to the weight of the load;
• and
• a plug coupled to the open end of the cylindrical cavity of the hollow housing, the plug configured to torsionally stiffen the hollow housing by preventing the open end of the cylindrical cavity from deforming;
• wherein the first and second pivotal joints comprise two corners of a parallelogram linkage structure.