Seating furniture having movable backrest

Abstract

The present invention relates to seating furniture, and more specifically, to seating furniture having a movable backrest, which allows a user's back to be supported by a backrest at all times in order to enable seating with proper posture, and comprises: a lower frame which is connected to a support; an upper frame which is connected to the lower frame via a vertical displacement generation means; at least one elastic body which is installed between the lower frame and upper frame; a back and forth moving means which is formed at the edge of the left and right sides of the upper frame, and is connected to a backrest frame to move back and forth; a power generation unit which converts the displacement according to the descent of the upper frame into a straight line movement at the back and forth moving means if a load is applied to a seat unit combined to the upper frame, thereby moving the backrest frame forward; and a switching unit which switches to a half-lock state in which the backrest frame can move forward only if a load is applied to the seat unit, and to an unlock state in which the backrest frame can move backward if the load applied to the seat unit is removed.

1 . A seating furniture having movable backrest, comprising:
 a lower frame which is connected to a support part;   an upper frame which is connected with the lower frame with an upper and lower displacement generation means being disposed between them;   at least one elastic part disposed between the lower frame and the upper frame;   a forward and backward movement means which is formed at the edge portions of left and right sides of the upper frame and is connected with the backrest frame and is movable in forward and backward directions;   a driving force generation part allowing the backrest frame to move in a forward direction as the displacement generating owing to the down movement of the upper frame is converted into a linear movement by means of a forward and backward movement means when a certain weight is applied to a seat part engaged to the upper frame; and   a switching part which becomes a half-lock state in which the backrest frame is movable only in a forward direction when a weight is applied to the seat part, and which becomes an unlock state in which the backrest frame is movable only in a backward direction when the weight having applied to the seat part is removed.   
     
     
         2 . A seating furniture having movable backrest according to  claim 1 , wherein said upper and lower displacement generation means is formed of a plurality of vertical slides or a plurality of foldable link plates, each of said vertical slides or said foldable link plates connecting the lower frame and the upper frame and linearly moving. 
     
     
         3 . A seating furniture having movable backrest according to  claim 2 , wherein said driving force generation part comprises:
 a vertical rack gear which is vertically installed at an upper surface of the lower frame;   a gear box which is engaged to the upper frame;   a pinion gear which is engaged with a first shaft installed at a lower side of the gear box and then is engaged with the vertical rack gear;   a vertical bevel gear which is engaged with the first shaft near the pinion gear;   a spur gear which is horizontally installed in the interior of the gear box wherein a horizontal bevel gear connected with the vertical bevel gear is installed at a lower surface of the spur gear and rotates; and   a horizontal rack gear which is engaged to a lower side of the backrest and is engaged with the spur gear and transfers a driving force to the backrest frame.   
     
     
         4 . A seating furniture having movable backrest according to  claim 3 , wherein said driving force generation part is formed of a stopper which is connected with a stop lever at one side of the spur gear, thus being selectively engaged with or disengaged from the spur gear. 
     
     
         5 . A seating furniture having movable backrest according to  claim 1 , wherein said switching part comprises:
 a rotation latch which is engaged in the interior of the upper frame in forward and backward directions, thus converting a rotation direction depending on the presence of a weight at the seat part; and   a latch hook which is connected with a lower surface of the backrest frame and is in a rotational operation within a limited angle range and is selectively engaged or disengaged with respect to the rotation latch.   
     
     
         6 . A seating furniture having movable backrest according to  claim 5 , wherein said seating furniture having a movable backrest is characterized in that the sear part is movable upward and downward with the rear end portion of the upper frame operating as a fixing part, and a pusher connected with a front end portion of the rotation latch is disposed at a lower surface of the front end portion of the seat part, thus allowing the rotation latch to rotate depending on the motion of the seat part. 
     
     
         7 . A seating furniture having movable backrest according to  claim 6 , wherein said pusher comprises:
 an upper pusher which faces a lower surface of the seat part;   a lower pusher of which an upper end portion is inserted through a lower side of the upper pusher and is movable, and a lower end portion is engaged with the rotation latch; and   a coil spring which is disposed between the upper pusher and the lower pusher.   
     
     
         8 . A seating furniture having movable backrest according to  claim 5 , wherein said switching part is characterized in that a latch guide with slot formed in forward and backward directions is disposed between the rotation latch and the latch hook, and two limit pins protruded with certain intervals from each other are disposed at the latch hook, and the latch hook passes though the slot, wherein the rotation angle of the latch hook is so limited that the latch hook is limited by two limit pins. 
     
     
         9 . A seating furniture having movable backrest according to  claim 5 , wherein said switching part is formed of a release lever by which the rotation latch can be adjusted to an unlock state by pressing a front end portion of the rotation latch.