Numerous attempts have been made to provide chairs—especially for office use—that are comfortable, and so do not tire out the person sitting in the chair even after sitting for a long time. Especially in an office, where a person may remain seated in a chair for an extended period, there is a marked tendency for the person to slouch in the chair, i.e. to slump down so that the person slides forward on the seat and so at least the lower back of the person moves to a more reclined position. It is well known that a slouched or slumped sitting position can cause or aggravate injury to a person's back.
What generally happens is simply that as a person tires, the person slides forward in the seat of the chair into a slouched position, and, already tired, tends not to expend the energy required to again assume a correct, non-slouching posture. Also a non-tired person can voluntarily assume the slouched position and find it difficult to correct this posture.
While the prior art teaches chairs in which the seat can be tilted to make slouching more difficult, the back of the chair generally tilts also, in synchrony with the seat, and the person ends up in a partially reclined position, which is generally considered not conducive to work. Chairs in which the back does not tilt, but the seat does are especially potentially harmful.
What is needed is a chair that addresses the tendency of a person to slide forward in a chair, but does so in a way that does not rely on a tilting of the seat or the back of the chair.