UW-Stout News Story

Professor co-invents ergonomic chair that receives U.S. patent

February 19, 2013

A University of Wisconsin-Stout professor is co-inventor for a new type of ergonomic chair that recently was granted a U.S. patent.

Ben Pratt, who teaches industrial design in the School of Art and Design, had a key role in the design from Nada-Concepts.

The chair incorporates the concept of a commercially successful back support sling that St. Paul company NadaChair has sold since 1985. The sling harnesses a user’s lower back to their shins, thereby stabilizing the pelvis and relieving muscles required to maintain good posture.

The Nada-Concepts chairThe patented chair provides the same support, without the sling. When someone sits in the chair, their weight activates two padded extensions that capture the shins. Pressure on the shins prevents the user from sliding forward.

“There is no other chair on the market like this. It has a lot of potential,” Pratt said.

According to the patent filing, “Many (chair) designs are directed towards adjustability, weight distribution and style but few designs ensure that the user is sitting properly in the chair.”

Victor Toso, NadaChair owner and founder, said that the failing of back supports in modern ergonomic chair design is a result of not having addressed the most basic principle of lever and fulcrum introduced in middle school.

"The back is like a long lever arm when sitting in the chair. The lumbar support in the chair acts like a fulcrum. Lean against the fulcrum and what do you expect? The weight below the fulcrum is pushed forward,” Toso said. “Thus, when a user leans against the so-called 'ergonomic' chair back, the lever effect immediately pushes the user forward on the seat pad, rendering the lumbar support useless."

The new patent prevents the forward slide on the seat pad, thereby making the lumbar support incrementally adjustable and effective.

Ben Pratt“There’s still a lot of work to be done. Mainly, it needs to be prototyped and go through a number of iterations before production,” Pratt said.

Pratt teaches a Furniture Design course and Design Concepts and Problems, as well as industrial design labs, at UW-Stout. He has industry experience with furniture design and medical equipment.

“Industrial design is the border between art and engineering,” Pratt said.

Pratt worked closely with Toso for months to arrive at the patented design. “It was a real pleasure to have Ben take what you’re visualizing and put dimensions on it,” Toso said.

David Prince, a 2007 UW-Stout graduate who lives in Eau Claire, helped with the computer-rendered design of the chair. He is listed on the patent with Pratt and Toso. Both have assigned their rights to Nada-Concepts.

Toso hopes to sell the rights to produce the chair to a major manufacturer. He also is in the process of obtaining patents for it in Europe and other parts of the world.

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