Patient chair with quaternary spring motion

Abstract

A patient chair has a support pedestal with a pair of front legs, a pair of rear legs, a pair of side members, a rear frame member connecting the two rear legs and a cross member connecting the side members at a location between the front and rear legs. A pair of leaf springs is attached to the underside of the cross member with portions thereof extending forwardly and rearwardly therefrom in a substantially horizontal manner. Each leaf spring includes a U-shaped bight or loop portion at the forwardmost extremity of the leaf spring coupling the forwardly extending portion with a horizontal overlying portion which passes over the cross member and extends rearwardly therefrom terminating in an orthogonally generally upwardly extending back support portion. A seat is fastened to the horizontal overlying portion of each leaf spring for receiving and supporting a chair occupant. Each leaf spring is provided with two spaced apart resilient members which are fixed to the chair and engage the horizontal overlying portion when the seat is supporting a load. The resilient members contribute to the spring action opposing closing of the U, but not to the spring effect opposing opening of the U.

What is claimed is:  
     
         1 . A chair having a seat, a backrest, a support pedestal adapted to rest on a floor or other horizontal support surface, and a pair of U-shaped compound springs coupling the seat and backrest to the pedestal, each spring having a longer portion, a shorter portion extending generally parallel to the longer portion, and a bight coupling the shorter and longer portions, the shorter portion fixed to the support pedestal intermediate the shorter portion free end and the bight, the seat fixed to the longer portion intermediate the bight and longer portion free end, and the backrest connected to the longer portion free end.  
     
     
         2 . The chair of  claim 1 , wherein each spring further includes a first resilient member fixed to one portion and engaging the other portion when the seat is supporting a load.  
     
     
         3 . The chair of  claim 2 , wherein the first resilient member is fixed to the shorter portion in substantially the same region as the region in which the shorter portion is fixed to the pedestal.  
     
     
         4 . The chair of  claim 2 , wherein each spring further includes a second resilient member spaced from the first resilient member, fixed to one of the portions and engaging the other portion when the seat is supporting a load.  
     
     
         5 . The chair of  claim 4 , wherein the second resilient member is fixed to one of the portions near the free end of the shorter portion.  
     
     
         6 . The chair of  claim 5 , wherein the first resilient member is fixed to the shorter portion in substantially the same region as the region in which the shorter portion is fixed to the pedestal and the second resilient member is fixed to the shorter portion near the free end of the shorter portion whereby, as an occupant slides rearwardly in the seat, or the load otherwise increases, the bight closes somewhat and the upper longer portion bends downwardly compressing the first and second resilient members and urging the free end of the shorter portion downwardly.  
     
     
         7 . The chair of  claim 5 , wherein, the first resilient member is fixed to the shorter portion in substantially the same region as the region in which the shorter portion is fixed to the pedestal and the second resilient member is fixed to the shorter portion near the free end of the shorter portion whereby, as an occupant slides forwardly in the seat, the lower portion intermediate the bight and region in which the shorter portion is fixed to the pedestal bends downwardly, the bight opens somewhat, and the upper longer portion bends upwardly separating from the first and second resilient members to aid occupant egress from the chair.  
     
     
         8 . The chair of  claim 1 , wherein the pedestal comprises a frame, two front legs and two rear legs extending downwardly therefrom, the forward extremity of the seat being located rearwardly of the front legs.  
     
     
         9 . The chair of  claim 8 , wherein the rear legs extend from the frame downwardly and rearwardly to provide an expanded pedestal rest area of enhanced stability.  
     
     
         10 . A patient chair, comprising: 
 a support pedestal having a pair of front legs, a pair of rear legs, a pair of side members, a rear frame member connecting the two rear legs and a cross member connecting the side members intermediate the front and rear legs; and    a pair of leaf springs attached to the underside of the cross member and having portions extending forwardly and rearwardly therefrom in a substantially horizontal manner, each leaf spring including a U-shaped bight portion at the forwardmost extremity of the leaf spring coupling the forwardly extending portion with a horizontal overlying portion which passes over the cross member and extends rearwardly therefrom terminating in an orthogonally generally upwardly extending back support portion.    
     
     
         11 . The chair of  claim 10 , further comprising a seat fixed to the horizontal overlying portion of each leaf spring for receiving and supporting a chair occupant.  
     
     
         12 . The chair of  claim 11 , wherein the seat is formed of a flexible, porous fabric sewn in to a hammock shape and disposed between the two leaf spring horizontally overlying portions.  
     
     
         13 . The chair of  claim 11 , further comprising a backrest fixed to the generally upwardly extending back support portion of each leaf spring.  
     
     
         14 . The chair of  claim 11 , wherein the front of each leaf spring extends forward of the cross member, but rearward of the front legs, curves substantially downward and loops rearwardly passing under the cross member.  
     
     
         15 . The chair of  claim 14 , wherein the leaf spring attaches to the cross member as it passes thereunder and continues rearwardly for a short distance past the cross member under and generally parallel to the leaf spring overlying portion.  
     
     
         16 . The chair of  claim 15 , wherein each leaf spring is provided with a first resilient member fixed to the cross member and engaging the horizontal overlying portion when the seat is supporting a load.  
     
     
         17 . The chair of  claim 16 , wherein leaf spring is further provided with a second resilient member spaced from the first resilient member and fixed to the spring in the region where the leaf spring continues rearwardly for a short distance past the cross member, the second resilient member engaging the horizontal overlying portion when the seat is supporting a load.  
     
     
         18 . The chair of claim a pair of armrests extending upwardly, then forwardly from the rear legs, and terminating forwardly of the seat forwardmost end and rearwardly of the forward most edge of the front legs.  
     
     
         19 . A chair support spring assembly, comprising: 
 a leaf primary spring fabricated from spring-steel, and shaped into a double cantilever spring-form of generally U-shape having a longer portion, a shorter portion extending generally parallel to the longer portion, and a bight coupling the shorter and longer portions;    a first resilient member fixed to one portion and engaging the other portion; and    a second resilient member spaced from the first resilient member, fixed to one of the portions and engaging the other portion.    
     
     
         20 . The chair support spring assembly of  claim 19 , wherein the first and second resilient members contribute forces opposing spring compression to close the U-shape from its unstressed position, while the forces opposing opening the U-shape are contributed solely by the leaf primary spring.