Patent ID: 6761410
Filing Date: 2004-07-13
Classification: A47C

Abstract:
A gear-controlled height-adjusting mechanism for an armrest of an office chair, comprising:a T-shaped armrest support including a flat top portion for the armrest to mount thereto and a flat long body extending downwardly from said flat top portion for fixing to a side of the office chair; a housing having at one side of an inner wall surface thereof a vertical row of equally spaced locating holes, wherein said armrest support is upwardly and downwardly slidably mounted in said housing; an elongate slide member movably connected to an upper outer side of said armrest support, such that said slide member can be pulled upward and released to elastically return to a lower position relative to said armrest support, said slide member including a handle laterally outwardly extending from a top of said slide member, and a rack downwardly extending from a lower end of said slide member with a plurality of teeth of said rack projected toward said armrest support; a gear set including a driving gear and a driven gear, which are connected to each other with a pivotal shaft to mount in an opening provided at a middle portion of said armrest support, said driving gear meshing with said rack on said slide member, said driven gear including a transmission gear and a locating gear that are integrally formed into one unit, said transmission gear having teeth adapted to engage with said locating holes on said housing; and said gear set also including a unidirectional catch means provided between said driving gear and said driven gear, said unidirectional catch means being adapted to bring said driven gear to rotate forward along with said driving gear when the latter rotates forward, and to idle when said driving gear rotates in a reverse direction; whereby when said handle of said slide member is alternately pulled upwardly and released, said driving gear meshing with said rack is caused by said rack to rotate forwardly and backwardly, respectively, and said driven gear is caused by said unidirectional catch means to rotate in one forward direction with said teeth of said transmission gear engaging with said locating holes on said housing to gradually move said armrest support upward in multiple stages and guided by said spaced locating holes, and a spring connected at an upper end to a lower outer end of said handle to provide a restoring force for elastically pulling said slide member to an initial lower position when said handle is pulled upwardly and then released.