Patent ID: 6397763
Filing Date: 2002-06-04
Classification: A47B

Abstract:
An adjustable support apparatus for supporting an object thereon that can be adjusted by a user, comprising:(a) a base; (b) a rotatable support arm capable of rotation relative to said base over at least a range of angular orientations, said support arm having first and second ends, said support arm comprising a first link having first and second ends, said first end of said first link coupled to said base at a first location so as to be capable of rotation about said base and so as to be capable of displacement relative to said base; (c) a support member for supporting said object, said support member coupled to said second end of said support arm; (d) an engageable and disengageable mechanism for locking rotation of said support arm about said base in at least a first direction, comprising: (i) first and second contact members formed on one of said base or said first end of said first link, said first and second contact members spaced apart by a distance and defining a line extending therethrough, (ii) at least a segment of a ring formed on the other of said base or said first end of said first link, said ring segment having inner and outer arcuate surfaces, said ring segment having a radius of curvature that defines a center thereof, said ring segment disposed between said first and second contact members, wherein, when said center of said ring segment radius of curvature is displaced a first distance from said line extending through said first and second contact members, application of a load on said support member causes said first contact member to impart a force on said ring segment inner surface and causes said second contact member to impart a force on said ring segment outer surface, said forces generating a friction force that restrains rotation of said first link in said first direction, whereby said locking mechanism is engaged and said support arm is restrained from rotation in said first direction, and wherein, when said first link and said base undergo relative displacement so that said center of said ring segment radius of curvature is displaced a second distance from said line that is less than said first distance, application of a load on said support member does not cause said first and second contact members to exert forces on said ring segment inner and outer surfaces, respectively, that generate friction forces that restrain rotation of said first link in said first direction, whereby said locking mechanism is disengaged and said support arm can be rotated in said first direction.