US 6,125,521 · Granted 2000-10-03
How Herman Miller's Stretching Machine Revolutionized Chair Comfort
Herman Miller figured out a clever way to make office chairs by stretching a flexible membrane tight, then using molds and injected plastic to lock it in place on a frame. It's like stretching fabric over a hoop, then reinforcing it so it stays perfectly taut without sagging over time.
The plain-English version
What it protects
The claim covers a manufacturing method where a membrane is stretched on a loom, held in that stretched state, transferred to a molding machine, and then surrounded by injected material that forms a carrier structure to permanently hold the stretched membrane in tension. What's protected is this specific sequence of steps and the resulting chair component—the combination of stretching, retention, and molded reinforcement that creates a durable support surface.
Why it matters
Office chairs are one of the most widely manufactured and purchased pieces of furniture globally. This patent protects Herman Miller's process for creating chair backs and seats that maintain their shape and support without sagging, a key competitive advantage in the ergonomic seating market. By combining fabric stretching with injection molding, the company solved the problem of fabric degradation under sustained pressure—a durability challenge competitors also face.
Real-world use
When you sit in a high-end office chair that feels supportive and doesn't sag after months of use, the stretched membrane locked in by molded carriers is likely working exactly as this patent describes.
Original USPTO abstract
A method of making an office chair by stretching a membrane in a stretching machine and retaining the stretched membrane on a loom. The loom, with the retained stretched membrane, is removed from the stretching machine and positioned between molds of a molding machine, wherein the molding machine is used to form a carrier member to hold a portion of the stretched member by injecting a material into a cavity formed between the molds to form a part of the chair.
Patent details
- Publication number
- US 6,125,521
- Filing date
- 1995-06-07
- Grant date
- 2000-10-03
- Assignee
- Herman Miller, Inc.
- Inventor(s)
- STUMPF; WILLIAM E., SCHOENFELDER; RODNEY C., CHADWICK; DONALD, KELLER; CAROLYN, COFFIELD; TIMOTHY P., SAYERS; RANDY J., BRUNER; JEFFREY W., CAMMENGA; ERIC
- CPC class
- A47C7/02
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