Adjustable back support for a seating surface

A back support for a chair includes a cover configured to be coupled to opposing sides of a chair frame. A strap is connected to the cover. A sled having a central portion is coupled to the strap, the sled is configured to pivot with respect to the chair frame and provide support to a user's back. The cover is configured to moveably connect to the chair frame between a low position and a high position. The sled is configured to pivot as the cover moves between the low position and the high position so that the central portion of the sled is substantially parallel to at least a portion of a membrane connected to the frame between the low position and the high position. 本发明公开种用于椅的背部支撑件，其包括被构造成联接到椅框架的相对侧的盖板。接片连接到所述盖板。具有中心部分的橇板联接到所述接片，所述橇板被构造成相对于所述椅框架枢转并向用户的背部提供支撑。所述盖板被构造成在低位置与高位置之间以可移动方式连接到所述椅框架。所述橇板被构造成当所述盖板在所述低位置与所述高位置之间移动时枢转，以使所述橇板的所述中心部分在所述低位置与所述高位置之间大致平行于连接到所述框架的隔板的至少部分。