Abstract: A backrest structure for a seat comprising a backrest frame which has a support structure and a front side facing the back of a seat user, a backrest cushion at the backrest frame a lumbar support mounted on the front side of the backrest frame for supporting the back of a seat user, an adjusting device for adjusting the position of the lumbar support perpendicular to the extension plane of the backrest frame and a curving element arranged on the front side of the backrest frame between the lumbar support and the backrest cushion. The curving element is secured to the support structure and the adjusting device acts on the curving element in order to adjust a curvature of the curving element. Furthermore, the backrest structure comprises at least one connecting element being connected to the curving element and the support structure, which connecting element applies a pre-tensioning force to the curving element in order to maintain the curving element in contact with the support structure.

Abstract: A backrest structure for a seat comprising a backrest frame which has a support structure and a front side facing the back of a seat user, a backrest cushion at the backrest frame a lumbar support mounted on the front side of the backrest frame for supporting the back of a seat user, an adjusting device for adjusting the position of the lumbar support perpendicular to the extension plane of the backrest frame and a curving element arranged on the front side of the backrest frame between the lumbar support and the backrest cushion. The curving element is secured to the support structure and the adjusting device acts on the curving element in order to adjust a curvature of the curving element. Furthermore, the backrest structure comprises at least one connecting element being connected to the curving element and the support structure, which connecting element applies a pre-tensioning force to the curving element in order to maintain the curving element in contact with the support structure.