US Patent 10179527 Support device for vehicle seat

A support device for a vehicle seat includes a bag body. The bag body includes a bag body assembly including at least a first bag body unit and a second bag body unit that are combined with each other. The first bag body unit is disposed to form at least a support surface facing the seated occupant when the first bag body unit is expanded, and the second bag body unit is disposed to press the support surface toward the seated occupant when the second bag body unit is expanded. The first and second bag body units are simultaneously supplied with air and expanded, and a surface of the second bag body unit that faces the seated occupant in an expanded state is smaller than the support surface of the first bag body unit that faces the seated occupant in an expanded state.