Chair having open shoulder backrest

Abstract

An ergonomically improved chair in which the user's thoracic region is supported by a narrow and generally flat or moderately convex thoracic cushion in the midrest region of the chairback. The design omits or greatly minimizes support for the user's scapulae and other areas of the back outside the thoracic region, excepting lumbar and cervical support features in some embodiments. The design differs from the prior art at least in that the thoracic cushion is narrow and configured not to complement that user's spinal curvature. By appropriate selection and design, a chair incorporating the invention may comprise a fabric covering portions of the chairback without significantly affecting functionality. Other embodiments include a chairback comprising regions having differing levels of firmness and/or differing cushion height at appropriate regions to promote concentrated support of the user's thoracic region.

I claim: 
     
         1 . A chair for a human user, said user having scapulae and further having lumbar and thoracic and cervical regions of the user's spine, said chair comprising:
 a seat platform;   a back support frame having a proximal end attached to the seat platform and a distal end extending above the proximal end;   a lumbar cushion having a front for supporting the lumbar region;   a midrest attached to the back support frame for supporting the thoracic region, said midrest separate and spaced apart from the lumbar cushion, said midrest situated between the lumbar cushion and the distal end, said midrest comprising a thoracic cushion having a width, the thoracic cushion further having a generally vertical length and a front;   wherein the thoracic cushion is less than five inches wide along at least two thirds of its length; and   said chair comprises no elements that engage the user's scapulae.   
     
     
         2 . The chair of  claim 1  further comprising: a neckrest cushion having a front for supporting the cervical region, wherein the neckrest cushion front and the lumbar cushion front generally define a first plane and the thoracic cushion front is behind the first plane. 
     
     
         3 . The chair of  claim 1  wherein the front of the thoracic cushion does not bend or curve to complement a dorsal spinal curvature of the user. 
     
     
         4 . The chair of  claim 1  wherein the thoracic cushion is less than four inches wide along at least two thirds of its length. 
     
     
         5 . The chair of  claim 1  wherein the back support frame is rigid. 
     
     
         6 . The chair of  claim 5  wherein the midrest is permanently secured to the back support frame, and wherein said midrest comprises a generally flat and vertically oriented thoracic cushion having a front that does not bend or curve to complement a dorsal spinal curvature of the user, said thoracic cushion being less than four inches wide along at least two thirds of its length. 
     
     
         7 . A chair for a human user having scapulae and further having lumbar and thoracic spinal regions, said chair comprising:
 a seat platform;   a back support frame having a proximal end and a distal end extending above the proximal end, the proximal end attached to the seat platform;   a lumbar cushion having a lateral width and a front for engaging the lumbar region;   a midrest attached to the back support frame between the lumbar cushion and the distal end for supporting the thoracic region, said midrest separate and spaced apart from the lumbar cushion, said midrest comprising a vertically oriented, substantially elongated thoracic cushion having a width and a generally vertical length and a front and an effective initial load deflection (ILD) firmness;   one or more interstitial areas laterally proximate to the thoracic cushion;   a chairback fabric attached to a fabric frame, the fabric frame configured to allow the fabric to hold an intended shape, the chairback fabric and fabric frame attached to the back support frame, the chairback fabric extending across at least one interstitial area wherein the chairback fabric covering the interstitial area that is laterally proximate to the thoracic cushion has an interstitial effective initial load deflection (ILD) firmness;   wherein the thoracic cushion is less than five inches wide along at least two thirds of its length; and   wherein the thoracic cushion effective initial load deflection (ILD) firmness is substantially higher than the interstitial effective initial load deflection (ILD) firmness such that the midrest primarily supports the seated user's thoracic spinal region and only minimally engages with the seated user's scapulae.   
     
     
         8 . The chair of  claim 7  wherein the chairback fabric is in direct contact with the thoracic cushion and with the lumbar cushion, the chairback fabric extending across at least the width of the thoracic cushion and the width of the lumbar cushion. 
     
     
         9 . The chair of  claim 7  further comprising a seat cushion on top of the seat platform, and wherein the fabric frame extends below the seat cushion. 
     
     
         10 . The chair of  claim 7  wherein the chairback fabric is in front of at least one cushion selected from the group consisting of: thoracic cushion and lumbar cushion. 
     
     
         11 . The chair of  claim 7  wherein the chairback fabric is behind at least one cushion selected from the group consisting of: thoracic cushion and lumbar cushion. 
     
     
         12 . The chair of  claim 7  further comprising a neckrest cushion having a front for engaging a cervical region of the user's spine, wherein the neckrest cushion front and the lumbar cushion front generally define a first plane, and wherein the thoracic cushion front is behind the first plane. 
     
     
         13 . The chair of  claim 7  wherein the thoracic cushion effective initial load deflection (ILD) firmness is above 28 and the interstitial area effective initial load deflection (ILD) firmness is below 24. 
     
     
         14 . A chair for a human user having scapulae and a thoracic spinal region, said chair comprising:
 a seat platform;   a back support frame having a proximal end and a distal end extending above the proximal end, the proximal end attached to the seat platform;   a chairback attached to the back support frame between the proximal end and the distal end, said chairback comprising a cushion having at least two cushion regions, the regions comprising a vertically oriented thoracic cushion region centrally situated in the chairback, the thoracic cushion region having an elevation and a front; and a scapular cushion region laterally abutting and extending from both sides of the thoracic cushion region, the scapular cushion region also having an elevation;   wherein the thoracic cushion region is less than five inches wide along at least two thirds of its length; and   wherein the thoracic cushion region's elevation is substantially greater than the proximately adjacent scapular cushion region elevation thereby creating a ridge, such that the chairback primarily supports the seated user's thoracic spinal region and only minimally engages with the seated user's scapulae.   
     
     
         15 . The chair of  claim 14  wherein the user has a lumbar region and wherein the chairback further comprises a lumbar cushion region, said lumbar cushion region situated approximately normal to the seated user's lumbar region and below the scapular cushion region, said lumbar cushion region having a front and having an elevation that is substantially greater than the proximately adjacent thoracic cushion region. 
     
     
         16 . The chair of  claim 15  wherein the human user has a cervical spinal region, and wherein the chair further comprises a neckrest cushion having a front for engaging the cervical spinal region; and wherein the neckrest cushion front and the lumbar cushion region front generally define a first plane, and wherein the thoracic cushion region front is behind the first plane. 
     
     
         17 . A chair for a human user having scapulae and a thoracic spinal region, said chair comprising:
 a seat platform;   a back support frame having a proximal end and a distal end extending above the proximal end, the proximal end attached to the seat platform;   a chairback attached to the back support frame between the proximal end and the distal end, said chairback comprising a cushion body having a vertically oriented thoracic cushion region laterally centered in the chairback, the thoracic cushion region having an effective initial load deflection (ILD) firmness; and a scapular cushion region laterally abutting and extending from both sides of the thoracic cushion region, the scapular cushion region generally normal to the seated user's scapulae, the scapular cushion region having an effective initial load deflection (ILD) firmness;   wherein the thoracic cushion region is less than five inches wide along at least two thirds of its length; and   wherein the thoracic cushion region's effective initial load deflection (ILD) firmness is substantially greater than the proximately adjacent scapular cushion region cushion effective initial load deflection (ILD) firmness, such that the chairback primarily supports the seated user's thoracic spinal region and only minimally engages with the seated user's scapulae.   
     
     
         18 . The chair of  claim 17  wherein the human user has a cervical spinal region and a lumbar region, and wherein the chair further comprises a neckrest cushion having a front for engaging the cervical spinal region; the chairback further comprising a lumbar cushion region having a front; wherein the neckrest cushion front and the lumbar cushion front generally define a first plane, and wherein the thoracic cushion front is behind the first plane. 
     
     
         19 . The chair of  claim 17  wherein the thoracic cushion region has a thoracic cushion region elevation and the scapular cushion has a scapular cushion region elevation, and wherein the thoracic cushion region's elevation is substantially greater than the proximately adjacent scapular cushion region.