A back support structure for a seat is known from European Patent Application No. 291,298. This application describes a seat measuring apparatus and a chair with an adjustable back, in which the adjustable back portion is formed by a pliable surface to which a number of metal strips can be attached. In order to obtain a curvature corresponding to that of a person's back, so as to allow measurement thereof, the deformable surface is provided with three supports allowing adjustment. Between the support locations the deformable surface is unrestrained by any positive means.
When considering the dynamics of vehicle collisions, and means for minimizing back and neck injuries, it is known that correct support of the back is very important, particularly as concerns the upper back, shoulders, neck and head. However, a seat back must also be easily adjustable in order to make it viable for use by people of different sizes. This is particularly true in vehicle seats which are standard for any particular car model. When considering a seat according to European Patent Application No. 291,298 (which primarily concerns a seat measurement apparatus and its application to a chair), obtaining conformity to a user's back is very complicated, requiring a large number of manipulations. Moreover, the assistance of a further person while the user is seated is required, if accurate conformity is to be obtained.
A known seat is disclosed in U.S. Pat. No. 5,120,109, which describes a standard car seat having several adjustable control sections, with a separate headrest portion attached by means of a control at the upper edge of the seat. Each of the adjustable sections comprises a panel having a number of parallel cords with intersecting cables which can be deformed into convex orientations of varying degrees of curvature. Such a seat does not, however, allow sufficient conformity to the actual shape of a user's back, but merely offers a compromise by supporting certain areas of the back by means of a series of standard convex surfaces which may or may not fit various users.
The main object of the present invention is thus to provide a seat back which is readily adjustable to provide good conformity, yet which provides positive support for the deformable support surface so as to provide a stable seat back structure.