US 5,934,758 · Granted 1999-08-10
The Wavy Grid Chair Back That Made Office Seating Flexible
Imagine a chair back made from a super-thin plastic shell with a crisscross grid of wavy strips woven into it—kind of like a stretchy net. The grid bends and flexes when you lean back, spreading your weight evenly across the whole surface so you stay comfortable for hours without the chair feeling too stiff or too soft.
The plain-English version
What it protects
The claim covers a chair seat or backrest design using a perforated plastic membrane with a gridlike pattern of interlocking wavy strips. What's protected is the specific construction: two series of wavy strips crossing each other in perpendicular directions, creating a grid that's held in place only around its outer edge by a ring frame. The grid distributes pressure evenly outward to that frame, which is how the cushioning works. Anyone making an office chair with this exact membrane structure—the wavy grid, the unsupported central region, the ring support—would infringe on this patent.
Why it matters
This patent represents a different approach to office chair engineering: instead of using foam or solid backing, Haworth patented a clever membrane structure that achieves ergonomic flexibility through geometry rather than materials. The wavy-strip grid is designed to distribute body pressure uniformly, which reduces hotspots and improves comfort during long workdays. This kind of innovation matters in the office furniture industry because comfort directly affects worker productivity and health, and patenting a novel structural solution can give a company a competitive edge in a crowded market.
Real-world use
When you sit in an office chair and lean back, your spine and shoulders press against the backrest. With this membrane design, that pressure spreads evenly across the wavy grid instead of creating hard pressure points, which is why the chair feels supportive without being rigid.
Original USPTO abstract
An office-type chair, having separate seat and back parts each cushioned and employing a thin inner plastic shell having a perforated central region formed as a thin membrane which is supported solely around the peripheral edge thereof by a suitable ringlike support frame. This membrane is semi-rigid in the plane thereof, but possesses at least limited resiliency in the thickness direction and, being free of direct underlying support, provides direct support for the cushion which in turn engages either the back or posterior of the user to provide limited flexibility and desirable comfort and ergonomic support. The membrane in the central region is provided with a first series of wavy strips which extend between the border of the membrane, with the first strips extending transversely across the membrane in one direction in spaced relationship, and a second series of wavy strips extending transversely across the membrane in the other transverse direction. The individual strips of the two series intersect and are integrally joined to provide the central region of the membrane with a gridlike construction. This gridlike construction which transmits transverse loading substantially uniformly radially outwardly to the surrounding border of the membrane, which border overlies and is fixed to the ringlike frame.
Patent details
- Publication number
- US 5,934,758
- Filing date
- 1997-04-30
- Grant date
- 1999-08-10
- Assignee
- Haworth, Inc.
- Inventor(s)
- RITCH; DAVID J., SAFFELL; MARK B., WILKERSON; LARRY A.
- CPC class
- A47C7/14
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