Patent Publication Number: US-2023157452-A1

Title: Seating device with a reclining function

Description:
TECHNICAL FIELD 
     The present invention relates to a seating device with a reclining function. 
     BACKGROUND 
     About 80 percent of adults experience low back pain at some point in their lives. It is the most common cause of work-related disability and a leading contributor to lost work days. It is therefore important that it is easy for everyone to find a good sitting position with a satisfactory backrest. 
     Since recliners/sofas with movable backs came on the market, there has been a challenge with too much/too little lumbar support and that the lumbar support in the chair moves in relation to the anatomy of the user&#39;s spine when the chair back is laid back (the chair opens). 
     When sitting in the chair/sofa with the backrest in a more or less upright position, a user will find it comfortable that the backrest is shaped according to the anatomy of the user&#39;s spine, i.e. with a small sway and extra support against the lower back. The extra lumbar support is also ergonomically correct when being in a sitting position. 
     The challenge comes when the back is lowered to a resting position. Depending on how many degrees the chair/sofa mechanism allows, the lumbar support will no longer be as comfortable. It simply feels too hard and has “moved” upwards and will hit the user on the upper side of the lower back. How much depends on the anatomy of the chair and the movement pattern of the mechanism. In a more supine sitting position, the need for lumbar support is less and a more “flat” support surface is more ergonomically correct. 
     Throughout the ages, this has been attempted solved through a lot of trial and error as well as several patents. Common to them all is that they have almost no effect, or may not achieve the desired effect, at the same time these mechanisms are often complicated. There is still a need for a simple and effective solution to these problems. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a sitting device which avoids the above-mentioned problems with previously known devices and further provides an adapted support for the lumbar spine both in a sitting and reclining, resting or lying position. 
     The above-mentioned objects of the invention are achieved with a device as stated in the following patent claims. 
     The scope of the invention is defined in the following claims. 
     More particularly, the invention comprises a reclining function seating device comprising a seat, a back element and a rotatable hinge member. 
     The invention also comprises a back frame for use in a sitting device with a reclining function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in detail with reference to the accompanying drawings, in which: 
         FIG.  1    is a sketch of the chair seen from a side with an upright backrest, 
         FIG.  2    is a sketch of the back frame seen from the front, 
         FIG.  3    is a sketch of the chair with a reclining backrest without load seen from one side, and 
         FIG.  4    is a sketch of the chair with a reclining backrest under load seen from one side. 
     
    
    
     Further features and advantages of the invention will become apparent from the following detailed description. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG.  1    shows a seating device  1  according to the invention with an upright backrest. The seating device  1  can be a chair, a sofa, a car seat, or the like. The seating device  1  comprises a seat  2 , a backrest element  3  and a rotatable hinge element (not shown in the drawing) which allows reclining function. 
     The backrest element  3  comprises a back frame  4  and padding  5 , for example in foam, where the padding  5  is arranged on one or both sides of the frame. 
       FIG.  2    shows the structure of the back frame  4  as well as a detailed sketch of a rotatable fastener  6 , where the arrow shows how the rotatable fasteners  6  are rotated. 
     The back frame  4 , which is formed as a forward-shaped part, comprises at least one first resilient element  7  and one or more second resilient elements  8 . The first resilient elements  7  are made of a material which is suitable for being made with prestress (bias) and which can withstand deformation during use, for example high carbon steel wire, molded plastic, rubber, curved steel strip, fiber casting, etc., preferably high carbon steel wire. The second resilient elements  8  are made of a material suitable for having a supporting or resilient effect, for example steel strip, plastic plate, textile webbing, fabric, rubber mat, high carbon steel wire, molded plastic, rubber, curved steel strip, fiber casting, etc. In case the resilient elements  7 ,  8  are made of steel wire, they may follow a zigzag pattern. The resilient elements  7  and  8  are independently bonded to the frame preferably at each end, either directly or via fasteners  6 , preferably via rotatable fasteners. The fasteners  6  can be made of, for example, plastic, metal, leather, fabric or fiber. 
     In one embodiment, the elements  7 ,  8  are resilient and arcuate before mounting. The first resilient (yielding) element  7  follows a curve which has a smaller radius compared to the radius of the one or more other resilient elements  8 . The first resilient element  7  is longer than the one or more other resilient elements  8 . Mounting of these elements  7 ,  8  on the frame  4  gives them a prestress. 
     The first resilient element  7  has a carefully determined prestress, matched firmness and fastening. The one or more other elements  8  are located above and below the first element  7  and are considerably firmer and flatter. Distance (position) and matched firmness are based on the ergonomics of the spine and how much the back “moves” in relation to the user&#39;s lumbar support and the effect of the user&#39;s weight on the yielding element. The chairs will be manufactured in different sizes and hardness adapted to the individual customer as well as markets in e.g. Europe and Asia. 
     When the user is sitting in an upright position as shown in  FIG.  1   , the forward-shaped or convex first resilient element  7  in the central back will largely retain the prestress (and create the desired lumbar support). The weight of the user sitting in the chair will largely decrease towards the seat  2 . The pressure/weight exerted against the backrest element  3  is therefore limited in this position and the desired lumbar support is maintained. 
       FIG.  3    shows the seating device  1  with a reclining backrest element  3  without load.  FIG.  4    shows the seating device  1  with a reclining backrest element  3  with load. 
     When the backrest element  3  of the seating device  1  is placed backwards, the user lying (sitting) in the chair will distribute the weight on both the seat  2  and the backrest element  3 , in relation to the upright position as shown in  FIG.  1   . The backrest element will thereby receive a significant greater weight against it. The padding  5  in the backrest element  3  is then compressed and deformed (flattened out). The first resilient element  7  now yields and acquires a more backward-bent or even concave shape. 
     The fasteners  6  will, due to their rotatability, reinforce this movement from the back frame. The back frame can be forward-striving, for example so that it follows the natural curvature of the user&#39;s back. 
     The padding  5  in the backrest element  3  is so soft that it yields to the extent that the weight exerted against the first resilient element  7  straightens and bends it backwards, but not so soft that the other elements  8  feel uncomfortable for the user. 
     The other elements  8  will stretch a little, but are less affected by these forces as they are harder, tighter and yield less compared to the first resilient element  7 . 
     The other elements  8 , on the other hand, must have a carefully positioned and coordinated firmness in order to “take over” the support of the first “yielding” element  7 . 
     All the resilient elements  7 ,  8  must be mounted in a coordinated relationship with each other and the design of the back frame  4 . 
     The total effect is that the padding  5  in the back element  3  becomes flatter in the supine position and the relative lumbar support is moved downwards because the other resilient elements  8  become more prominent than the first resilient element  7  in the supine position. On a normal chair/sofa, the area for lumbar support on the back of the chair that meets the spine will move upwards when the backrest element  3  is laid down (the chair opens). On the described seating device  1 , the back frame  4  will become more prominent in the supine position and a more correct position, pressure and position of the lumbar support in relation to the anatomy of the spine of the user is maintained.