| 摘要 |
PURPOSE: To eliminate a parallelogrammic link and simplify a construction of a frame for chair by making a joint on a knee side as a helicoidal spring joint to make tensile strength of the spring adjustable and supporting a prop on a supporting arm by means of the spring part. CONSTITUTION: A sitting part 5 and a back-leaning part 6 are fixed or connected with each other by a joint. The sitting part 5 is guided archedly around a supporting arm 2 to form a helicoidal spring joint 10 and fixed to a pivot connector 11 under the helicoidal spring joint. A adjustment screw 13 is attached to a lever 12 extending from the helicoidal spring joint. The adjustment screw 13 is rotatable under the supporting arm 2. The lever 12 moves in a covering or leaving direction to the supporting arm 2 by rotation of the adjustment screw. The supporting arm 2 increases or decreases a deviation on the knee side of the helicoidal spring joint 10.
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