主权项 |
1. A height-adjustable table comprising:
a) a work surface; b) a vertically movable frame adapted to support the work surface, the frame comprising:
i) a cross-member;ii) a first upper leg and a second upper leg connected to the cross-member, the upper legs being spaced apart and extending downwardly from the cross-member, wherein the frame defines a passage, the passage extending through the first upper leg, the cross member, and the second upper leg; c) a first lower leg and a second lower leg, wherein the first upper leg telescopes within the first lower leg, and the second upper leg telescopes within the second lower leg; d) a pulley mechanism comprising:
i) a first plurality of pulleys located in the passage; andii) a first tension line and a second tension line passing through the first plurality of pulleys, the first line being adapted for vertically moving the first upper leg within the first lower leg and the second line being adapted for vertically moving the second upper leg within the second lower leg; e) a spring located in the passage and having a fixed end connected to the frame and a movable end adapted to move a first distance relative to the fixed end, wherein the spring is adapted to exert an upward force on the frame over the first distance; f) a block-and-tackle assembly located in the passage, the block-and-tackle assembly comprising:
i) a fixed block having a second plurality of pulleys and being connected to the frame,ii) a movable block having a third plurality of pulleys and being connected to the movable end of the spring such that a displacement of the movable end of the spring relative to its fixed end results in a displacement of the movable block relative to the fixed block,iii) a third tension line threaded between the second and third plurality of pulleys and secured at one end to one of the fixed block and the movable block and at another end to the first line, wherein the block-and-tackle assembly is adapted to cooperate with the pulley mechanism to transfer the upward force exerted by the spring over the first distance to the frame, wherein the force exerted by the spring over the first distance contributes to upward vertical movement of the frame over a second distance, the second distance being greater than the first distance. |