Backrest chair, and a sheet material for use thereon

A backrest chair characterized in that a core sheet is formed by attaching a shape retaining material capable of elastic bending deformation to mesh sheets capable of elastic bending deformation, to have an elastic resilience for assuming a backrest shape in a natural state and to be elastically displaceable while maintaining a backrest state by a stretching force in a use situation;

• that a chair sheet material is formed by providing a buffer sheet to cover a surface of the core sheet which is in the use situation on a back side of a seated person in a seated position;
• that a right and left width of a backrest portion of the chair sheet material is made larger than a breadth of the seated person's shoulders, and when a load of the seated person is applied to the backrest portion of the chair sheet material, right and left opposite ends of the backrest portion of the chair sheet material can be displaced in directions to approach each other due to elasticity of the core sheet;
• and that the chair sheet material is attached to a chair support frame lower than a seat surface in a state of positioning the core sheet and the buffer sheet on a back and a rear surface of a head of the seated person, and wherein the chair sheet material is characterized in that a cut hole is formed to penetrate the core sheet and the buffer sheet and having a length approximately corresponding to a half of an entire circumference of a seat portion, the backrest chair being constructible by attaching the chair sheet material to the chair support frame by fitting the cut hole on the chair support frame.

A backrest chair characterized in that a core sheet is provided with a shape retaining material made capable of elastic bending deformation by a high-strength carbon fiber sheet, to have an elastic resilience for assuming a backrest shape in a natural state and to be elastically displaceable while maintaining a backrest state by a stretching force in a use situation;

• that a chair sheet material is formed by providing a buffer sheet to cover a surface of the core sheet which is in the use situation on a back side of a seated person in a seated position;
• that a right and left width of a backrest portion of the chair sheet material is made larger than a breadth of the seated persons shoulders, and when a load of the seated person is applied to the backrest portion of the chair sheet material, right and left opposite ends of the backrest portion of the chair sheet material can be displaced in directions to approach each other due to elasticity of the core sheet;
• and that the chair sheet material is attached to a chair support frame lower than a seat surface in a state of positioning the core sheet and the buffer sheet on a back and a rear surface of a head of the seated person, and wherein the chair sheet material is characterized in that a cut hole is formed to penetrate the core sheet and the buffer sheet and having a length approximately corresponding to a half of an entire circumference of a seat portion, the backrest chair being constructible by attaching the chair sheet material to the chair support frame by fitting the cut hole on the chair support frame.