Chester Carlson's Original Xerography Patent
Chester Carlson's 1942 patent for xerography, the dry copying process that became the foundation for Xerox machines.
Original patent title: “Electrophotography”
Chester Carlson's 1942 patent for xerography, the dry copying process that became the foundation for Xerox machines. Granted to Individual in 1942 with 737 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
This patent describes the fundamental process of xerography, a method for making dry copies of documents. It involves charging a surface with static electricity, exposing it to an image to create an electrostatic latent image, dusting the charged surface with a dry powder (toner), transferring that powder to paper, and then fusing the powder to make the image permanent. The core idea is using static electricity to attract toner particles to form an image, which is then heated to create a lasting copy.
The gap
What does this patent NOT cover?
- Does not cover wet copying processes
- Does not cover processes that use liquid developers instead of dry powder
- Does not cover methods that do not involve an electrostatic latent image
- Does not cover processes that do not use heat to fuse the toner
- Does not cover digital scanning or printing technologies
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
Carlson's genius was in combining several existing scientific principles—photoconductivity, electrostatics, and powder adhesion—into a single, practical process for image reproduction that was far simpler and faster than existing methods.
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
Early Xerox copiers
Modern office document printers
Laser printers
Photocopiers
Why it matters
The bigger picture
This patent is the bedrock of modern document copying. Chester Carlson's invention of xerography directly led to the creation of Xerox Corporation and revolutionized office document reproduction, making fast, dry copies accessible to businesses worldwide.
Filed
April 4, 1939
Granted
October 6, 1942
Market context
Who's building on this
Companies in this space
Xerox Corporation, as the direct descendant of Carlson's invention, remains a key player. However, the fundamental principles of xerography are now so widespread that virtually all manufacturers of laser printers and copiers, including Canon, HP, and Brother, build upon this foundational technology.
Market impact
This patent created an entirely new market for document copying and printing. It enabled the rise of Xerox as a dominant company and fundamentally changed office workflows by making information reproduction fast, efficient, and widely available, paving the way for the digital printing revolution.
Claim 1 — Plain English
What this patent covers
This patent describes the fundamental process of xerography, a method for making dry copies of documents. It involves charging a surface with static electricity, exposing it to an image to create an electrostatic latent image, dusting the charged surface with a dry powder (toner), transferring that powder to paper, and then fusing the powder to make the image permanent. The core idea is using static electricity to attract toner particles to form an image, which is then heated to create a lasting copy.
The clever bit
Carlson's genius was in combining several existing scientific principles—photoconductivity, electrostatics, and powder adhesion—into a single, practical process for image reproduction that was far simpler and faster than existing methods.
What it does not cover
- Does not cover wet copying processes
- Does not cover processes that use liquid developers instead of dry powder
- Does not cover methods that do not involve an electrostatic latent image
- Does not cover processes that do not use heat to fuse the toner
- Does not cover digital scanning or printing technologies
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
0/20
Narrow claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
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
$45K – $144K
Midpoint $90K · 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.
Concepts involved
Citations
Patent lineage
Cite this patent
Carlson, C. F. (1942). Chester Carlson's Original Xerography Patent (U.S. Patent No. 2,297,691). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/2297691/xerography-electrophotography-photocopier
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 Chester Carlson's Original Xerography Patent cover?
Chester Carlson's 1942 patent for xerography, the dry copying process that became the foundation for Xerox machines.
Who owns patent US 2297691?
Individual owns this patent, granted in 1942.
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 2297691 cited by?
This patent has been cited by 737 later patents that build on its ideas.
What problem does this patent solve?
This patent is the bedrock of modern document copying. Chester Carlson's invention of xerography directly led to the creation of Xerox Corporation and revolutionized office document reproduction, making fast, dry copies accessible to businesses worldwide.
What does this patent NOT cover?
Does not cover wet copying processes
Same assignee
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