Patent ID: 6264276
Filing Date: 2001-07-24
Classification: A47C

Abstract:
A concealable height adjusting device adapted to be mounted between a seat member and a backrest member of a chair, the backrest member extending in an upright direction, said height adjusting device comprising:a mounting frame including a proximate end portion adapted to be secured to the seat member, and a distal end portion extending from said proximate end portion in the upright direction and adapted to be disposed rearwardly of the backrest member;an elongated sliding member adapted to be secured to the backrest member; anda slidable and unidirectionally retaining mechanism disposed between said distal end portion and said elongated sliding member to position said distal end portion relative to said elongated sliding member, said retaining mechanism including:a linear-movement actuated engaging member including:a mounting portion with first and second mounting walls opposite to each other in a first transverse direction relative to the upright direction;a pawl portion having a pivot end pivotally mounted to said first mounting wall about a pivot axis parallel to the first transverse direction, and an engaging end provided with an engaging key which extends in the first transverse direction; anda first biasing member disposed to bias said engaging key to turn clockwise about the pivot axis, and to displace in a second transverse direction which is transverse to both the upright direction and the first transverse direction, a multilevel engaged member including:first and second retaining walls opposite to each other in the first transverse direction and slidable relative to said first mounting wall of said mounting portion in the upright direction, said first retaining wall having first and second inner lateral edges spaced apart from each other in the second transverse direction to define a keyway extending in the upright direction between upper and lower limits to receive and permit said engaging key to move relative to said keyway between said upper and lower limits, said first inner lateral edge defining a plurality of notches spaced apart from one another in the upright direction, and between said upper and lower limits, said notches extending in the second transverse direction and being communicated with said keyway so as to form a plurality of ratchet teeth such that once said multilevel engaged member has been moved downward to a first position where said upper limit is brought to abut against said engaging key, an initial upward movement of said multilevel engaged member from the first position will permit said engaging key to be biased by said first biasing member to move into and be engaged within one of said notches, and a subsequent upward movement thereof will cause said engaging key to slide over a corresponding one of said ratchet teeth against the biasing action of said first biasing member and to move into and be engaged within a next one of said notches until a second position is reached where said engaging key abuts against said lower limit;an arrest member disposed to be moved with said multilevel engaged member from the first or second position so as to release said engaging key or to grip said engaging key such that said engaging key is confined within said keyway when said multilevel engaged member is being moved downward from the second position to the first position; anda barrier member disposed to hinder said arrest member from being moved with the upward movement of said multilevel engaged member so as to set said arrest member ready for moving with the downward movement of said multilevel engaged member to grip said engaging key.