Back Adjusting and Positioning Structure of Chair

Abstract

A back adjusting and positioning structure of a chair is characterized in that: a backward tilt adjustment unit is disposed at the junction of a cushion frame and a back frame of the chair so that the backward tilt adjustment unit drives a screw segment with one end thereof extending inward to retract and/or protrude a blocking element coupled to a rear segment thereof in response to a knob's rotating in a predetermined direction, so as to control compression and/or expansion of a predetermined stop distance acquired by a spring fitted in the backward tilt adjustment unit, and in consequence the back in operation attains the required tightening and/or loosening state.

What is claimed is: 
     
         1 . A back adjusting and positioning structure of a chair, adapted for adjusting, including loosening and/or tightening, a back of the chair, characterized in that: a backward tilt adjustment unit is disposed at a junction of a cushion frame and a back frame of the chair, and the backward tilt adjustment unit comprises a knob with a screw segment extending therefrom, a spring for controlling the resilience of the back, a blocking element for carrying the spring to undergo inward and outward displacement, and a support element abutting against a related segment of the cushion frame,
 wherein, after a pad has been fitted into the screw segment extending from the knob, guiding a support segment of the back frame into a pipe segment, fitting a pad into the screw segment, and meshing a screw nut with the screw segment so that the knob is confined to the support segment of the back frame, wherein the screw segment extending inside of the back frame guides in the blocking element coupled to the screw nut so that the blocking element undergoes predetermined inward and outward displacement along the screw segment in response to the rotation of the knob,   wherein the spring is mounted on an inner side of the blocking element, and another end of the spring is confined to a recess region attributed to the support element and positioned proximate to the cushion frame, and at least one concealment member is disposed within the range of motion of the spring,   wherein, to adjust the loosening and tightening of the back, the backward tilt adjustment unit drives a screw segment with an end thereof extending inward to retract and/or protrude the blocking element coupled to a rear segment thereof in response to the knob's rotating in a predetermined direction, so as to control compression and/or expansion of a predetermined stop distance acquired by a spring fitted in the backward tilt adjustment unit, and in consequence the back in operation attains a required tightening and/or loosening state.   
     
     
         2 . The back adjusting and positioning structure of a chair according to  claim 1 , wherein the concealment member disposed within the range of motion of the spring included in the backward tilt adjustment unit and adapted to control the resilience of the back comprises an inner sleeve and an outer sleeve, with an inward bent edge formed at an end of the inner sleeve to engage with a protruding segment disposed at a related part of the back frame, and an inward bent edge formed at an opposing end of the outer sleeve to engage with an inward region attributed to the support element and positioned proximate to the cushion frame, so that the inner and outer sleeves and the range of motion of the spring maintain a concealment state conducive to environmental isolation. 
     
     
         3 . The back adjusting and positioning structure of a chair according to  claim 1 , wherein the concealment member is disposed within the range of motion of the spring included in the backward tilt adjustment unit and adapted to control the resilience of the back, and a predetermined segment located inside of the inner sleeve extends to form at least one bump so that a limit is placed on the inward and outward displacement of the blocking element coupled to a rear segment of the screw segment extending from an end of the knob, thereby maintaining stable retraction and/or protrusion. 
     
     
         4 . The back adjusting and positioning structure of a chair according to  claim 2 , wherein the concealment member is disposed within the range of motion of the spring included in the backward tilt adjustment unit and adapted to control the resilience of the back, and a predetermined segment located inside of the inner sleeve extends to form at least one bump so that a limit is placed on the inward and outward displacement of the blocking element coupled to a rear segment of the screw segment extending from an end of the knob, thereby maintaining stable retraction and/or protrusion. 
     
     
         5 . The back adjusting and positioning structure of a chair according to  claim 1 , wherein, when the blocking element which the screw nut is coupled to is guided in along the screw segment extending from an end of the knob included in the backward tilt adjustment unit, a restriction portion meshes with an inner end of the screw segment extending, so as to place a directional limit on the retraction of the blocking element. 
     
     
         6 . The back adjusting and positioning structure of a chair according to  claim 1 , wherein a guidance application is disposed between the inner sleeve and the outer sleeve of the concealment member of the backward tilt adjustment unit, that is, two outer sides at an end of the inner sleeve each extend to form a bump for engaging with a recess disposed on an inner side of the outer sleeve so as to maintain a stable concealment together with the range of motion of the spring. 
     
     
         7 . The back adjusting and positioning structure of a chair according to  claim 4 , wherein a guidance application is disposed between the inner sleeve and the outer sleeve of the concealment member of the backward tilt adjustment unit, that is, two outer sides at an end of the inner sleeve each extend to form a bump for engaging with a recess disposed on an inner side of the outer sleeve so as to maintain a stable concealment together with the range of motion of the spring. 
     
     
         8 . A back adjusting and positioning structure of a chair, wherein a directional coupling of a cushion portion and the back of the chair is characterized in that: the junction of the cushion frame and the back frame of the chair extends to form supporting portions; holes are penetratingly formed in the supporting portions at the junction of the cushion frame and the back frame; after a spring has been inserted into a pipe segment, thrusting segments are disposed along two sides of the spring to abut against the pipe segment, outer screw segments of the two thrusting segments are guided out of the holes formed in the supporting portions at the junction of the cushion frame and the back frame so that the directional mounting and/or demounting of the back frame and the cushion frame achieves quick positioning and/or removal by inserting and/or retracting the two thrusting segments capable of appropriate resilient stop.