Fixed or movable seat or bed backrest with adjustable curvature - has movable horizontal spacer between base plate and resilient support (SW 14.11.77)

Back rest is formed by a rigid rectangular case plate (10) with two longitudinal edges connected by two transverse edges by a curved resilient support (20) which is connected to the base plate at the two transverse edges so that it can be displaced at at least one edge. A spacer (13) designed as a full-length support is mounted in the space between the base plate (10) and the support member (20) where it is pressed against the base plate owing to the elasticity of the support member and lies with its ends near the longitudinal edges of the plate. The length of the spacer is equal to the width of the base plate and its position can be adjusted so that the desired curvature of the support member can be set relative to the base plate. The base plate is provided along at least the middle parts of the longitudinal edges with locking elements (16).