Adjustable support

An adjustable support comprising:

• a first pivot mechanism defining a first axis of rotation;
• a second pivot mechanism defining a second axis of rotation parallel to the first axis of rotation;
• and
• a polygonal structure connecting the first pivot mechanism to the second pivot mechanism, wherein said polygonal structure comprises:
• a top member;
• a bottom member;
• a proximal member;
• a distal member;
• means coupling the top member, bottom member, proximal member, and distal member to form an articulated parallelogram structure;
• a constraint link having a first end, a second end and a distal portion, the first end being rotatably coupled to the top member and the second end being rotatably coupled to the bottom member, the distal portion including a coupling point;
• and
• means pivotally connected to said coupling point for moving said constraint link to affect the shape of the parallelogram.

An adjustable support comprising:

• a first pivot mechanism defining a first axis of rotation;
• a second pivot mechanism defining a second axis of rotation parallel to the first axis of rotation;
• a rigid tubular sleeve having a first flat internal surface;
• a polygonal structure including a portion having a first flat external surface closely received within said sleeve and slidably engaging said first flat internal surface of said sleeve, said polygon structure connecting the first pivot mechanism to the second pivot mechanism.

An adjustable support comprising:

• a first pivot mechanism defining a first axis of rotation;
• a second pivot mechanism defining a second axis of rotation parallel to the first axis of rotation;
• a sleeve;
• a top member;
• a bottom member;
• a proximal member;
• a distal member;
• means coupling the top member, bottom member, proximal member, and distal member to form an articulated parallelogram structure, a portion of said parallelogram structure being disposed within and slidably engaging said sleeve and connecting the first pivot mechanism to the second pivot mechanism;
• a constraint link having a first end, a second end and a distal portion, the first end being rotatably coupled to the top member and the second end being rotatably coupled to the bottom member, the distal portion including a coupling point;
• and
• means pivotally connected to said coupling point for moving said constraint link to affect the shape of the parallelogram.