US 5,975,634 · Granted 1999-11-02
The Ergonomic Chair Patent That Redefined Office Seating
Imagine a chair that actually moves with you when you lean back—the seat slides forward and the back flexes to support your spine in exactly the right spots. This patent locks down a whole system of adjustments: your lower back gets custom support, the seat depth changes to fit your legs, and a clever spring mechanism lets you tune the recline tension without tools.
The plain-English version
What it protects
The claim covers a chair with a base, a pivoting back assembly, and a seat that slides forward as you recline. What's protected here is the specific combination of a flexible back with adjustable lumbar support connected at top and bottom, a seat with depth adjustment and thigh support, plus a spring-tension adjuster with an overtorque safety device that prevents mechanical damage when you tighten or loosen the recline stiffness.
Why it matters
Office chairs are one of the most-used pieces of furniture in the world, and bad ergonomics cost companies billions in worker compensation and lost productivity. This patent represents a major advance in how chairs accommodate different body types and postures—by making the back flex, the seat slide, and the lumbar support adjustable without special tools, Steelcase created a category of responsive seating that competitors would have to design around or license.
Real-world use
Every time you adjust your office chair to sit more comfortably during a long study session or work call, you're benefiting from the kind of multi-axis adjustment this patent protects.
Original USPTO abstract
A chair is provided having a base assembly, a back assembly pivoted to the base assembly for movement between upright and reclined positions, and a seat slidably supported on the base assembly and pivoted to the back frame so that the seat moves forwardly and its rear moves forwardly and downwardly with the back frame upon recline. A flexible back is connected to the back frame at top and bottom locations and is provided with lumbar adjustment for improved lumbar force/support and shape. A seat is provided with seat depth adjustment and with active and passive thigh flex support. A novel energy mechanism is provided that includes a moment arm shift adjuster for adjusting the spring tension on the back frame. The moment arm shift adjuster is readily adjustable and includes an overtorque device to prevent damage to components of the energy mechanism.
Patent details
- Publication number
- US 5,975,634
- Filing date
- 1997-10-24
- Grant date
- 1999-11-02
- Assignee
- Steelcase Development Inc.
- Inventor(s)
- KNOBLOCK; GLENN A., DAMMERMANN; ARNOLD B., DEKRAKER; LARRY, EKDAHL; KEVIN A., HEIDMANN; KURT R., KLAASEN, II; GARDNER J., PERKINS; JAMES A., PETERSON; GORDON J., PUNCHES; EDWARD H., ROOSSIEN; CHARLES P., TEPPO; DAVID S., YANCHARAS; MICHAEL J.
- CPC class
- A47C1/023
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