How Buried Channel CCDs Move Data Deep Inside Silicon Chips
A foundational 1974 invention that improved how computer chips store and move electrical charges by keeping them away from messy surface defects.
Original patent title: “Buried channel charge coupled devices”
A foundational 1974 invention that improved how computer chips store and move electrical charges by keeping them away from messy surface defects. Granted to Individual in 1974 with 14 claims and 22 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
This patent describes a way to move electrical charges through the middle of a semiconductor material rather than along its surface. By creating a 'buried channel'—a specific potential energy path deep inside the silicon—the device prevents charges from getting trapped by surface defects, which were a major problem in early chip designs. The device uses a series of electrode plates on the surface to pull these charges along this internal path, essentially acting like a bucket brigade for electrons. This allows for much faster and more reliable movement of data within the chip.
The gap
What does this patent NOT cover?
- Does not cover charge-coupled devices that store or transfer charge directly on the semiconductor surface.
- Does not cover memory structures that rely on traditional floating-gate transistors for long-term storage.
- Does not cover devices lacking the specific ohmic contact means required to bias the storage medium for internal depletion.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
Instead of fighting surface defects, the inventors moved the 'highway' for electrons into the bulk of the material, using an electrical bias to create a potential energy 'valley' that keeps charges safely away from the surface.
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
Digital camera image sensors
Early digital video camcorders
High-speed analog signal delay lines
Why it matters
The bigger picture
This invention was critical for the evolution of digital imaging and high-speed signal processing. By solving the charge-trapping problem, it enabled the creation of high-quality Charge-Coupled Device (CCD) sensors, which became the standard for early digital cameras and video recorders. It essentially allowed engineers to build more reliable and sensitive silicon-based sensors.
Filed
April 19, 1973
Granted
February 12, 1974
Market context
Who's building on this
Companies in this space
The technology was pioneered at Bell Labs by Willard Boyle and George Smith, who later won the Nobel Prize for this work. Today, major semiconductor manufacturers and sensor companies like Sony, Samsung, and ON Semiconductor continue to refine the underlying physics of charge transfer in CMOS and CCD image sensors.
Market impact
This patent provided the technical foundation for the digital imaging revolution. It enabled the transition from analog film to digital sensors, eventually leading to the ubiquity of cameras in every smartphone and professional imaging system worldwide.
Claim 1 — Plain English
What this patent covers
This patent describes a way to move electrical charges through the middle of a semiconductor material rather than along its surface. By creating a 'buried channel'—a specific potential energy path deep inside the silicon—the device prevents charges from getting trapped by surface defects, which were a major problem in early chip designs. The device uses a series of electrode plates on the surface to pull these charges along this internal path, essentially acting like a bucket brigade for electrons. This allows for much faster and more reliable movement of data within the chip.
The clever bit
Instead of fighting surface defects, the inventors moved the 'highway' for electrons into the bulk of the material, using an electrical bias to create a potential energy 'valley' that keeps charges safely away from the surface.
What it does not cover
- Does not cover charge-coupled devices that store or transfer charge directly on the semiconductor surface.
- Does not cover memory structures that rely on traditional floating-gate transistors for long-term storage.
- Does not cover devices lacking the specific ohmic contact means required to bias the storage medium for internal depletion.
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
Early stage
Citation count
27/40
Moderately cited
Claim breadth
9/20
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
$16K – $50K
Midpoint $32K · expired or expiring · industry ×1.4
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
0 independent claims · 1 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
14 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Smith, G., & Boyle, W. (1974). How Buried Channel CCDs Move Data Deep Inside Silicon Chips (U.S. Patent No. 3,792,322). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/3792322/ccd-image-sensor
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 Buried Channel CCDs Move Data Deep Inside Silicon Chips cover?
A foundational 1974 invention that improved how computer chips store and move electrical charges by keeping them away from messy surface defects.
Who owns patent US 3792322?
Individual owns this patent, granted in 1974.
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 3792322 cited by?
This patent has been cited by 22 later patents that build on its ideas.
What problem does this patent solve?
This invention was critical for the evolution of digital imaging and high-speed signal processing. By solving the charge-trapping problem, it enabled the creation of high-quality Charge-Coupled Device (CCD) sensors, which became the standard for early digital cameras and video recorders. It essentially allowed engineers to build more reliable and sensitive silicon-based sensors.
What does this patent NOT cover?
Does not cover charge-coupled devices that store or transfer charge directly on the semiconductor surface.
Same assignee
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