How Thomas Edison Invented the Practical Incandescent Light Bulb
Thomas Edison's 1880 patent for a carbon-filament electric lamp that made indoor lighting reliable and commercially viable for the first time.
Original patent title: “Electric lamp”
Thomas Edison's 1880 patent for a carbon-filament electric lamp that made indoor lighting reliable and commercially viable for the first time. Granted to Individual in 1880 with 28 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
The patent describes an electric lamp using a high-resistance carbon filament enclosed in a vacuum-sealed glass bulb. By using a carbonized thread or strip of paper as the filament, Edison achieved a stable light source that could burn for hundreds of hours. The vacuum prevents the filament from burning up instantly upon contact with oxygen, allowing it to glow brightly when electricity passes through it.
The gap
What does this patent NOT cover?
- Does not cover the invention of the electric arc lamp, which relies on a different physical principle.
- Does not cover modern LED or fluorescent lighting technologies.
- Does not cover the electrical grid or power distribution systems required to power the lamp.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The innovation was the use of a high-resistance carbon filament in a near-perfect vacuum, which allowed the bulb to operate efficiently on a parallel electrical circuit rather than the high-voltage series circuits used by earlier, less practical designs.
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 incandescent light bulbs
Carbon-filament lamps used in 19th-century homes and factories
Why it matters
The bigger picture
This patent marks the transition from gas lighting to the modern era of electricity. It provided the core component for the first widespread, safe, and long-lasting indoor lighting system, effectively launching the global electric utility industry.
Filed
November 4, 1879
Granted
January 27, 1880
Market context
Who's building on this
Companies in this space
General Electric, founded by Edison, became the primary steward of this technology for decades. Today, the lighting industry has transitioned to LED manufacturers like Signify and Cree, which build on the fundamental concept of controlled electrical illumination.
Market impact
This patent enabled the electrification of cities and the creation of the modern electric utility sector. It rendered gas lighting obsolete and set the standard for residential and industrial lighting for over a century.
Claim 1 — Plain English
What this patent covers
The patent describes an electric lamp using a high-resistance carbon filament enclosed in a vacuum-sealed glass bulb. By using a carbonized thread or strip of paper as the filament, Edison achieved a stable light source that could burn for hundreds of hours. The vacuum prevents the filament from burning up instantly upon contact with oxygen, allowing it to glow brightly when electricity passes through it.
The clever bit
The innovation was the use of a high-resistance carbon filament in a near-perfect vacuum, which allowed the bulb to operate efficiently on a parallel electrical circuit rather than the high-voltage series circuits used by earlier, less practical designs.
What it does not cover
- Does not cover the invention of the electric arc lamp, which relies on a different physical principle.
- Does not cover modern LED or fluorescent lighting technologies.
- Does not cover the electrical grid or power distribution systems required to power the lamp.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Early stage
Citation count
29/40
Moderately 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
$9K – $29K
Midpoint $18K · expired or expiring · industry baseline
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
Edison, T. A. (1880). How Thomas Edison Invented the Practical Incandescent Light Bulb (U.S. Patent No. 223,898). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/223898/edison-incandescent-lamp
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 Thomas Edison Invented the Practical Incandescent Light Bulb cover?
Thomas Edison's 1880 patent for a carbon-filament electric lamp that made indoor lighting reliable and commercially viable for the first time.
Who owns patent US 223898?
Individual owns this patent, granted in 1880.
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 223898 cited by?
This patent has been cited by 28 later patents that build on its ideas.
What problem does this patent solve?
This patent marks the transition from gas lighting to the modern era of electricity. It provided the core component for the first widespread, safe, and long-lasting indoor lighting system, effectively launching the global electric utility industry.
What does this patent NOT cover?
Does not cover the invention of the electric arc lamp, which relies on a different physical principle.
Same assignee
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