How the Floppy Disk's Protective Jacket Cleans the Disk
An IBM patent from 1972 describing a protective, non-removable cover for a magnetic disk that uses a built-in cleaning material to wipe the disk surface while it spins.
Original patent title: “Magnetic record disk cover”
An IBM patent from 1972 describing a protective, non-removable cover for a magnetic disk that uses a built-in cleaning material to wipe the disk surface while it spins. Granted to International Business Machines Corp in 1972 with 9 claims and 79 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
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.
The gap
What does this patent NOT cover?
- 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.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The innovation lies in using the disk's own rotation against a stationary, low-friction, porous lining to achieve self-cleaning, effectively turning the protective sleeve into a maintenance tool.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
The 8-inch floppy disk
The 5.25-inch floppy disk
Why it matters
The bigger picture
This technology was essential for the commercial viability of the floppy disk. By integrating a cleaning layer directly into the jacket, IBM ensured that the fragile magnetic surfaces could survive the dusty, uncontrolled environments of early office and home computing without frequent data corruption.
Filed
December 22, 1969
Granted
June 6, 1972
Market context
Who's building on this
Companies in this space
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.
Market impact
This patent helped standardize the form factor of early removable magnetic storage, enabling the transition from massive, fragile disk packs to portable, reliable disks. It effectively solved the reliability issues that had previously hindered the mass adoption of flexible magnetic media in personal computing.
Claim 1 — Plain English
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.
The clever bit
The innovation lies in using the disk's own rotation against a stationary, low-friction, porous lining to achieve self-cleaning, effectively turning the protective sleeve into a maintenance tool.
What it does not cover
- 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.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Moderate
Citation count
38/40
Highly cited
Claim breadth
6/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$34K – $108K
Midpoint $68K · expired or expiring · industry ×1.5
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Patent Claims
1 independent claim · 0 dependent
Claims are the legal boundaries of the patent. An independent claim stands alone. A dependent claim adds limitations to its parent, narrowing — but not broadening — the scope.
The original legal language
Original claims
9 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Flores, R., & Thompson, H. E. (1972). How the Floppy Disk's Protective Jacket Cleans the Disk (U.S. Patent No. 3,668,658). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3668658/floppy-disk-diskette
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How the Floppy Disk's Protective Jacket Cleans the Disk cover?
An IBM patent from 1972 describing a protective, non-removable cover for a magnetic disk that uses a built-in cleaning material to wipe the disk surface while it spins.
Who owns patent US 3668658?
International Business Machines Corp owns this patent, granted in 1972.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 3668658 cited by?
This patent has been cited by 79 later patents that build on its ideas.
What problem does this patent solve?
This technology was essential for the commercial viability of the floppy disk. By integrating a cleaning layer directly into the jacket, IBM ensured that the fragile magnetic surfaces could survive the dusty, uncontrolled environments of early office and home computing without frequent data corruption.
What does this patent NOT cover?
Does not cover disks that are intended to be removed from their protective covers by the user.
Same assignee
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