You can freely build on How the Modern Waterbed Works

What this patent covers

The patent describes a furniture support, specifically a sofa or bed, that uses a flexible, inelastic bladder filled with liquid to support multiple people. The system requires a rigid frame to hold the liquid and prevent the sides of the bladder from bulging outward. A key feature is that the bladder is filled completely, leaving no air inside, which allows the surface to conform to the body's shape while ensuring the person remains suspended by the liquid. It also includes an optional heating element to keep the liquid at a comfortable temperature and solid particles like styrofoam to stop the liquid from sloshing around when someone moves.

What is now free to use

All 1 claims of US 3585356 are in the public domain. Specifically:

• Claim 1: In a support of the sofa type for floatably supporting a plurality of adult human bodies, a bladder formed of a flexible

The 0 dependent claims add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• Does not cover air mattresses or inflatable supports that rely on gas rather than liquid.

• Does not cover waterbeds that allow the user to touch the bottom surface (the patent requires the body to be supported entirely by the liquid).

• Does not cover flexible bladders that are not contained within a rigid lateral framework.

• Does not cover liquid supports that contain significant amounts of air within the bladder.

Who is building on this today

The original assignee, Innerspace Environments, helped establish the early market. Today, the technology is largely maintained by specialized bedding manufacturers who focus on therapeutic and orthopedic sleep solutions that utilize fluid-based pressure redistribution.

Products built on expired version of this technology

How to cite this patent in your documentation

Innerspace Environments Inc. US Patent 3585356. Liquid support for human bodies. Granted 1971, expired 1990. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.