Abstract: A seat includes a seat frame, and a cushion material supported by the seat frame and having a three-dimensional knitted fabric which is formed by joining, with connecting threads, a pair of ground knit fabrics which are disposed so as to be separated from one another. The cushion material includes a first region whose elastic compliance when a reaction force is applied to an extending side of the cushion material when an occupant is seated on the seat is substantially equivalent to an elastic compliance of a portion of the occupant's body pressing the cushion material and a second region whose elastic compliance is larger than that of the first region. Accordingly, a thin and light seat can be provided, load concentration on the occupant's tuber ishiadicum bottom portion when seated for a long period of time can be mitigated, and vibration-transmitting characteristics can be improved.

Abstract: An upper end portion of a seat backrest and a lower end portion of a head rest are superposed together. A rear end portion of an upper portion cushion member and a lower end portion of the seat backrest are superposed together. These superposed portions are sewn together by thin threads which break when pressing force of a predetermined value or greater is applied to the seat backrest. Thus, when pressing force of the predetermined value or greater is applied to the seat backrest, the thin threads break. A portion of the seat backrest which a shoulder portion of a seated occupant contacts, and a portion of the seat backrest which buttocks of the seated occupant contact, are enlarged, and impact force can be damped.

Abstract: A seat comprising a seat frame, and a cushion material supported by the seat frame and having a three-dimensional knitted fabric which is formed by joining, with connecting threads, a pair of ground knit fabrics which are disposed so as to be separated from one another, wherein the cushion material comprising a first region whose elastic compliance when a reaction force is applied to an extending side of the cushion material when an occupant is seated on the seat is substantially equivalent to an elastic compliance of a portion of the occupant's body pressing the cushion material and a second region whose elastic compliance is larger than that of the first region. Accordingly, a thin and light seat can be provided, load concentration on the occupant's tuber ishiadicum bottom portion when seated for a long period of time can be mitigated, and vibration-transmitting characteristics can be improved.

Abstract: An upper end portion of a seat backrest and a lower end portion of a head rest are superposed together. A rear end portion of an upper portion cushion member and a lower end portion of the seat backrest are superposed together. These superposed portions are sewn together by thin threads which break when pressing force of a predetermined value or greater is applied to the seat backrest. Thus, when pressing force of the predetermined value or greater is applied to the seat backrest, the thin threads break. A portion of the seat backrest which a shoulder portion of a seated occupant contacts, and a portion of the seat backrest which buttocks of the seated occupant contact, are enlarged, and impact force can be damped.