Constant force spring with active bias

An extensible support device comprising:

• a bracket;
• a sliding assembly fixed to the bracket;
• a vertical column coupled to the sliding assembly at an upper end and supporting a load at a lower end, the sliding assembly allowing the vertical column to move in a vertical direction;
• a drum rotatably coupled to the bracket;
• a constant force spring having a first end coupled to the drum and a second end coupled to the vertical column, the constant force spring counterbalancing gravitational forces on the vertical column;
• and
• a motor having a rotor coupled to the bracket and a stator coupled to the drum.

An extensible support device comprising:

• a bracket;
• a motor coupled to the bracket;
• a drum coupled to the motor such that the drum can rotate with respect to the bracket;
• means for supporting a load that is movable in a vertical direction;
• a constant force spring coupled to the drum at a first end and coupled to the means for supporting the load at a second end, the constant force spring counterbalancing gravitational forces on the load;
• and
• a control module coupled to the motor to apply a controlled compensating force to the drum.

A method for supporting a load that is movable in a vertical direction, the method comprising:

• supporting the load from a lower end of a vertical column;
• supporting an upper end of the vertical column on a sliding assembly fixed to a bracket;
• coupling a motor to the bracket;
• coupling a drum to the motor such that the drum can rotate with respect to the bracket;
• coupling a first end of a constant force spring to the drum;
• coupling a second end of the constant force spring to the vertical column to counterbalance gravitational forces on the vertical column;
• and
• applying a controlled compensating force to the drum with the motor.