You can freely build on How the Floppy Disk's Protective Jacket Cleans the Disk

What this patent covers

This patent describes a protective sleeve for a magnetic disk that remains stationary while the disk spins inside it. The inside of this sleeve is lined with a special porous, antistatic material that stays in physical contact with the disk surface. As the disk rotates, this lining acts like a constant wiper, removing dust and contaminants that could otherwise cause read or write errors. The cover also includes a specific opening, or transducing aperture, which allows the magnetic read/write head of the computer drive to touch the disk surface to access data.

What is now free to use

All 1 claims of US 3668658 are in the public domain. Specifically:

• Claim 1: In a magnetic recording system, the combination — 3 specific elements

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 disks that are intended to be removed from their protective covers by the user.

• Does not cover storage systems where the disk and the protective cover rotate together as a single unit.

• Does not cover cleaning mechanisms that are separate from the disk's permanent housing.

• Does not cover optical storage media like CDs or DVDs.

Who is building on this today

IBM originally pioneered this design, which became the standard for the entire floppy disk industry throughout the 1970s and 1980s. While floppy disks are now obsolete, the fundamental concept of integrating protective, self-cleaning housings for sensitive media influenced later cartridge-based storage designs.

Products built on expired version of this technology

How to cite this patent in your documentation

International Business Machines Corp. US Patent 3668658. Magnetic record disk cover. Granted 1972, expired 1989. 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.