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Archaic Legal Glossary & Citations

“Letters Patent”14th–20th Century
19th-C Meaning:

Open public letters from a monarch or government (literae patentes) granting monopoly rights.

Modern Engineering Decoded:Issued USPTO utility or design patent publication.
Historical note: Contrasted with 'letters close' (private sealed royal correspondence).
“In testimony whereof”19th Century
19th-C Meaning:

Formal concluding legal formula affirming under oath the execution of the instrument.

Modern Engineering Decoded:Inventor and witness digital/physical signatures.
Historical note: Required two witness attestations in 19th-century USPTO filing procedure.
“Aeroplane”Early 20th Century (Wright era)
19th-C Meaning:

A flat or cambered lifting aerofoil surface supported dynamically by air pressure.

Modern Engineering Decoded:Wing / Airfoil lifting surface (later evolved to mean the entire motorized aircraft).
Historical note: The Wrights used 'aeroplane' to denote the individual fabric-covered wings.
“Undulating Current”19th Century (Bell era)
19th-C Meaning:

An electric current whose magnitude varies continuously and periodically without interruption.

Modern Engineering Decoded:Continuous analog AC or audio-frequency electrical waveform.
Historical note: Bell's central legal weapon against telegraph companies who relied on pulsed DC make-and-break circuits.
“Subdivision of the Electric Light”1870s–1880s (Edison era)
19th-C Meaning:

The problem of operating numerous small domestic lamps off a single electrical generator.

Modern Engineering Decoded:Parallel circuit wiring of high-resistance incandescent electrical loads.
Historical note: Pundits claimed it was physically impossible until Edison increased filament resistance to 100 ohms.
“Optically Anisotropic Solution”1960s (Kwolek era)
19th-C Meaning:

A liquid solution that exhibits direction-dependent refractive indices due to molecular alignment.

Modern Engineering Decoded:Liquid crystalline nematic phase polymer dope.
Historical note: Technicians initially tried to throw out Kwolek's cloudy solution thinking it was contaminated.
“Unitary Body of Semiconductor Material”1950s–1960s (Noyce era)
19th-C Meaning:

A single continuous crystal structure of silicon or germanium.

Modern Engineering Decoded:Monolithic single-crystal silicon die / integrated circuit wafer.
Historical note: Differentiated Noyce's monolithic planar circuit from Jack Kilby's hybrid flying-wire prototype.
“Peculiar and Novel Construction”19th Century
19th-C Meaning:

A distinctive, patentable structural arrangement not found in prior art.

Modern Engineering Decoded:Novel and non-obvious mechanical embodiment under 35 U.S.C. § 103.
Historical note: Standard 19th-century legal terminology establishing novelty.

Museum Broadside & Archival Print Edition

Authentic archival layout formatted for framing, study, and high-resolution printing

Paper:
Theme:
The United States Patent & Trademark Archive

Historical Specification & Engineering Broadside

Curated, Verified & Restored by Classic Patents (classic-patents.com)
MINIATURIZED ELECTRONIC CIRCUITSSingle-Crystal Semiconductor Substrate Integrating Transistors, Bulk Resistors, and P-N Junction Capacitors
US 3,138,743Class: 257/500
Inventor(s):Jack S. Kilby
Origin / Location:Dallas, Texas
Grant & Filing:Filed February 6, 1959 · Granted June 23, 1964

I. Historical Context & Grant Summary

Jack Kilby's historic 1964 master patent for Miniaturized Electronic Circuits—the foundational Texas Instruments breakthrough that invented the Monolithic Integrated Circuit (Microchip). Created during the famous 'monolithic idea' summer of 1958 at TI, Kilby realized that if all circuit components—active transistors and diodes, passive bulk resistors, and p-n junction capacitors—were fabricated entirely out of a single piece of semiconductor material (germanium or silicon), the 'Tyranny of Numbers' (interconnection failure) would be broken forever. Kilby demonstrated the first working monolithic integrated circuit (a phase-shift oscillator on a sliver of germanium) on September 12, 1958, sparking the microelectronics revolution that powers every computer, smartphone, and spacecraft on Earth.

II. Core Mechanism & Scientific Principles

In the late 1950s, the electronics industry ran into a catastrophic roadblock known as the 'Tyranny of Numbers.' While discrete transistors had replaced bulky vacuum tubes, complex computers and military guidance systems required hundreds of thousands of individual components—each with two or three hand-soldered wire leads. With so many soldered joints, statistically, systems failed almost immediately after being turned on. In the hot summer of 1958 at Texas Instruments in Dallas, Jack Kilby was a newly hired engineer who had not yet accrued vacation time. Left alone in the laboratory while senior staff were away, Kilby asked a profound question: If Texas Instruments is a semiconductor company that knows how to manipulate silicon and germanium, why use other materials at all? Kilby realized that resistors could be carved out of semiconductor bulk material, capacitors could be made from reverse-biased p-n junctions, and transistors could be built on the same piece. On September 12, 1958, Kilby demonstrated the first working monolithic integrated circuit in human history—a phase-shift oscillator on a sliver of germanium about the size of a postage stamp.

Physical Operation:Kilby's Monolithic Integrated Circuit operates by co-fabricating all circuit organs within a single continuous crystal wafer: (1) Bulk Semiconductor Resistors: Electric current flowing through a shaped channel of doped semiconductor encounters bulk resistance governed by Ohm's law and resistivity ($R = ho L / A = R_{ ext{sheet}} cdot L / W$). By etching narrow serpentine mesas, precise resistor values from $100;Omega$ to $100; ext{k}Omega$ are formed directly in the silicon/germanium bar without discrete resistors. (2) P-N Junction Capacitors: When a p-n junction is reverse-biased, mobile charge carriers are pulled away from the interface, leaving an insulating depletion zone of width $W_{ ext{dep}} = sqrt{2 arepsilon (V_{ ext{bi}} + V_R) / (q N_d)}$. This depletion layer acts as a dielectric between the conductive p and n regions, creating an integrated voltage-variable capacitor ($C = arepsilon A / W_{ ext{dep}}$). (3) Mesa Bipolar Transistors: By sequentially diffusing acceptor (p) and donor (n) impurities into the substrate and etching mesa plateaus, active NPN or PNP transistors with high current gain ($eta = I_c / I_b approx 50 ext{–}150$) are formed right alongside the passive resistors and capacitors. (4) Interconnection: Kilby used fine gold flying wires bonded via thermal compression to connect the mesa tops into a functioning flip-flop or oscillator circuit.
Governing Formulation:
Semiconductor Bulk Sheet Resistance & Geometric Scaling:R = R_{ ext{sheet}} left( rac{L}{W} ight) = rac{ ho}{t} left( rac{L}{W} ight) = rac{1}{q (mu_n n + mu_p p) t} left( rac{L}{W} ight)
P-N Junction Depletion Transition Capacitance:C_j(V_R) = A sqrt{ rac{q arepsilon_s N_a N_d}{2 (N_a + N_d) (V_{ ext{bi}} + V_R)}} = rac{ arepsilon_s A}{W_{ ext{dep}}(V_R)}
BJT Current Amplification & Monolithic RC Circuit Dynamics:I_c = eta I_b quad ext{and} quad f_{ ext{osc}} = rac{1}{2 pi R C sqrt{6}}

III. The Granted Legal Monopoly (Key Claims)

Claim 1 (Independent)Single-crystal junction-transistor array

A single-crystal semiconductor wafer carries several junction transistors and several thin, elongated semiconductor regions that serve as resistors. Each transistor has opposite-conductivity base and emitter layers over a collector, with both junctions reaching one major face; selected resistor regions are spaced from the transistors and conductively connected to them.

Claim 2 (Independent)Single-crystal transistor-resistor pair

A single-crystal wafer contains one junction transistor and one resistor on the same major face. The transistor's opposite-conductivity layers overlie one another, both emitter-base and base-collector junctions reach that face, and the resistor is a separate elongated semiconductor region spaced away from the transistor.

Claim 3 (Independent)Active/passive wafer integration

An integrated circuit uses a semiconductor wafer with at least one active component and one passive component. The active component has opposite-conductivity thin layers whose junctions reach one major face; the passive component occupies a discrete region spaced from those layers, with substantial impedance through the material between them.

IV. Mechanical Organ Breakdown

Monolithic Semiconductor SubstrateTerm: “Wafer or bar of single-crystal semiconductor material” → Monolithic semiconductor substrate / Silicon wafer

A single continuous wafer of single-crystal germanium or silicon acting as common structural host and collector.

Integrated Bulk Semiconductor ResistorTerm: “Elongated resistor region / bulk semiconductor path” → Diffused / Well Semiconductor Resistor

Narrow shaped mesa path of semiconductor material providing defined linear resistance between ohmic contacts.

Integrated P-N Junction CapacitorTerm: “Capacitor defined by a p-n junction / reverse-biased junction” → Junction Varactor / MOS Capacitor

Reverse-biased semiconductor junction utilizing depletion zone width as dielectric layer.

Mesa Diffused Bipolar TransistorTerm: “Mesa transistor / thin layers of opposite conductivity types” → Integrated Bipolar Junction Transistor (BJT)

Active three-layer (collector-base-emitter) switching and amplifying element isolated by mesa chemical etching.

CLASSIC PATENTS DIGITAL ARCHIVE • PERMANENT EXHIBIT ID: us-3138743-kilby-integrated-circuit
classic-patents.com/patents/us-3138743-kilby-integrated-circuit
Original USPTO PDF
Classic Patents/US 3,138,743
Mid-Century Electronic, Nuclear & Materials Revolution (1920–1990)Microchips, Solid Circuits & Semiconductor Integration

Jack Kilby Monolithic Integrated Circuit

US 3,138,743

Single-Crystal Semiconductor Substrate Integrating Transistors, Bulk Resistors, and P-N Junction Capacitors

Inventor(s)Jack S. Kilby
Grant DateJune 23, 1964
Filing DateFebruary 6, 1959
LocationDallas, Texas
Jack Kilby's historic 1964 master patent for Miniaturized Electronic Circuits—the foundational Texas Instruments breakthrough that invented the Monolithic Integrated Circuit (Microchip). Created during the famous 'monolithic idea' summer of 1958 at TI, Kilby realized that if all circuit components—active transistors and diodes, passive bulk resistors, and p-n junction capacitors—were fabricated entirely out of a single piece of semiconductor material (germanium or silicon), the 'Tyranny of Numbers' (interconnection failure) would be broken forever. Kilby demonstrated the first working monolithic integrated circuit (a phase-shift oscillator on a sliver of germanium) on September 12, 1958, sparking the microelectronics revolution that powers every computer, smartphone, and spacecraft on Earth.
USPTO PDF
Audio Engineering Breakdown~3 min listen

Listen to the narrated mechanical breakdown and civilizational context

Engineering Analysis & Physical Principles

How It Works: Step-by-Step Mechanical & Physical Breakdown

In the late 1950s, the electronics industry ran into a catastrophic roadblock known as the 'Tyranny of Numbers.' While discrete transistors had replaced bulky vacuum tubes, complex computers and military guidance systems required hundreds of thousands of individual components—each with two or three hand-soldered wire leads. With so many soldered joints, statistically, systems failed almost immediately after being turned on. In the hot summer of 1958 at Texas Instruments in Dallas, Jack Kilby was a newly hired engineer who had not yet accrued vacation time. Left alone in the laboratory while senior staff were away, Kilby asked a profound question: If Texas Instruments is a semiconductor company that knows how to manipulate silicon and germanium, why use other materials at all? Kilby realized that resistors could be carved out of semiconductor bulk material, capacitors could be made from reverse-biased p-n junctions, and transistors could be built on the same piece. On September 12, 1958, Kilby demonstrated the first working monolithic integrated circuit in human history—a phase-shift oscillator on a sliver of germanium about the size of a postage stamp.
The Core Breakthrough Mechanism

Kilby's Monolithic Integrated Circuit operates by co-fabricating all circuit organs within a single continuous crystal wafer: (1) Bulk Semiconductor Resistors: Electric current flowing through a shaped channel of doped semiconductor encounters bulk resistance governed by Ohm's law and resistivity (R=hoL/A=RextsheetcdotL/WR = ho L / A = R_{ ext{sheet}} cdot L / W). By etching narrow serpentine mesas, precise resistor values from 100;Omega100;Omega to 100;extkOmega100; ext{k}Omega are formed directly in the silicon/germanium bar without discrete resistors. (2) P-N Junction Capacitors: When a p-n junction is reverse-biased, mobile charge carriers are pulled away from the interface, leaving an insulating depletion zone of width Mathematical notation unavailable. This depletion layer acts as a dielectric between the conductive p and n regions, creating an integrated voltage-variable capacitor (Mathematical notation unavailable). (3) Mesa Bipolar Transistors: By sequentially diffusing acceptor (p) and donor (n) impurities into the substrate and etching mesa plateaus, active NPN or PNP transistors with high current gain (Mathematical notation unavailable) are formed right alongside the passive resistors and capacitors. (4) Interconnection: Kilby used fine gold flying wires bonded via thermal compression to connect the mesa tops into a functioning flip-flop or oscillator circuit.

Interactive Real-Time Physical Simulation

Drag to rotate · Pinch to zoom · Shared controls update the displayed model
INITIALIZING THREE.JS WEBGL SIMULATION...
Source-Bounded Monolithic Semiconductor Circuit Topology.
Host-Model Telemetry/Computed Readout
Source-Bounded Monolithic Semiconductor Circuit Topology
Semiconductor Section Reveal
Normalized
0% illustrative reveal[1]
Wire 70 Arch
Normalized
0.55normalized drawing geometry[1]
Printed Wafer
Source
0.200 × 0.080 × 0.0025in[1]
Antimony N Layer
Source
0.7mil[1]
Figure 7 Printed Values
Source
400 / 1800 / 3000 Ω · 50 µF[1]
Claim 1 Conductive Means
Source Refusal
present[1]
Electrical Performance
Source Refusal
refused[1]
Displayed Semiconductor Section Reveal
∂s_{display} / ∂s_{reader} (host sensitivity)
1 fraction / fraction
Semiconductor Section Reveal0 fraction
Thermally Bonded Wire Arch0.55 fraction
Interval ghosts
section reveal0.0 fraction · [0, 1]
wire 70 arch0.6 fraction · [0.2, 1]
Fidelity / MMS residual
Figure 6a wafer dimensions
model0.200 × 0.080 × 0.0025 in (length × width × thickness)
reference0.200 × 0.080 × 0.0025 in (length × width × thickness)
residual0 in (length × width × thickness)
Dated scenarios

Detailed Component Architecture

1Monolithic Semiconductor Substrate
A single continuous wafer of single-crystal germanium or silicon acting as common structural host and collector.

High-purity crystalline semiconductor with controlled donor doping (Ndapprox1015extcm−3N_d approx 10^{15} ext{ cm}^{-3}) providing carrier mobility munapprox3800extcm2/extVcdotextsmu_n approx 3800 ext{ cm}^2/ ext{V}cdot ext{s} (Ge) or 1400extcm2/extVcdotexts1400 ext{ cm}^2/ ext{V}cdot ext{s} (Si).

19th-C. Term: Wafer or bar of single-crystal semiconductor materialModern: Monolithic semiconductor substrate / Silicon wafer
2Integrated Bulk Semiconductor Resistor
Narrow shaped mesa path of semiconductor material providing defined linear resistance between ohmic contacts.

Resistance Mathematical notation unavailable, where sheet resistance Mathematical notation unavailable. Length-to-width aspect ratio determines total resistance.

19th-C. Term: Elongated resistor region / bulk semiconductor pathModern: Diffused / Well Semiconductor Resistor
3Integrated P-N Junction Capacitor
Reverse-biased semiconductor junction utilizing depletion zone width as dielectric layer.

Transition junction capacitance Mathematical notation unavailable, providing voltage-controlled AC signal coupling and filtering.

19th-C. Term: Capacitor defined by a p-n junction / reverse-biased junctionModern: Junction Varactor / MOS Capacitor
4Mesa Diffused Bipolar Transistor
Active three-layer (collector-base-emitter) switching and amplifying element isolated by mesa chemical etching.

Vapor-diffused base layer (tbapprox1.5;muextmt_b approx 1.5;mu ext{m}) and alloyed emitter dot delivering current gain alpha=0.985alpha = 0.985, Mathematical notation unavailable, with collector cutoff frequency fT>25extMHzf_T > 25 ext{ MHz}.

19th-C. Term: Mesa transistor / thin layers of opposite conductivity typesModern: Integrated Bipolar Junction Transistor (BJT)
5Thermal Compression Wire Bond Interconnects
Gold flying wires bonded with heat and pressure to bridge isolated component mesas into functional circuits.

Fine gold wire (Dapprox25;muextmD approx 25;mu ext{m}) thermo-compression bonded at 300circextC300^circ ext{C} directly to alloyed ohmic gold-germanium contact pads.

19th-C. Term: Conductor means / gold bonding wires / flying leadsModern: Wire Bonding / Planar Metal Interconnects
Engineering Principles & Equations

Governing Equations & Engineering Principles

Authored explanation paired with its stated mathematical relation

Semiconductor Bulk Sheet Resistance & Geometric Scaling

Solid-State Physics & Integrated Circuit Design
Mathematical Governing Law
Terms:
Plain English DecoderHover or tap any highlighted phrase
The total equals multiplied by over , derived from and .
RR
Integrated Bulk Resistance
Total electrical resistance of the shaped semiconductor path (Ω).
Ω

Determines the collector load and base bias resistances in the monolithic solid circuit.

Physical Principle & Engineering Insight

Bulk semiconductor resistance depends linearly on the aspect ratio L/W, allowing precise resistor values to be shaped directly into the semiconductor crystal substrate without discrete resistors.

P-N Junction Depletion Transition Capacitance

Semiconductor Device Physics
Mathematical Governing Law
Terms:
Plain English DecoderHover or tap any highlighted phrase
The across depends on , , and , scaling inversely with plus and .
CjC_j
P-N Junction Transition Capacitance
Dynamic small-signal capacitance of the reverse-biased junction (pF).
pF

Acts as an integrated capacitor for AC coupling and filter networks.

Physical Principle & Engineering Insight

Reverse-biased p-n junctions create an insulating charge-depleted layer that acts as a dielectric, providing integrated microchip capacitors whose value is dynamically tunable by applied voltage.

Semiconductor Bulk Sheet Resistance & Geometric ScalingAuthored Principle 1
Stated relationMathematical notation unavailable
Governs the resistance of integrated semiconductor paths. By controlling dopant concentration and mesa aspect ratio, precise resistor networks are created directly inside the crystal.
P-N Junction Depletion Transition CapacitanceAuthored Principle 2
Stated relationMathematical notation unavailable
Reverse-biased p-n junctions act as parallel-plate capacitors whose dielectric thickness expands with applied reverse voltage, enabling integrated coupling capacitors.
BJT Current Amplification & Monolithic RC Circuit DynamicsAuthored Principle 3
Stated relationMathematical notation unavailable
Bipolar transistor current amplification combined with integrated RC feedback networks produces self-sustained oscillations and bistable flip-flop digital switching inside a single monolithic bar.

Interactive Schematic Sheet (Figure 1)

Perspective cross-section of semiconductor wafer showing bulk resistor formed by shaped semiconductor path and capacitor formed by reverse-biased p-n junction.

1.00x
US 3,138,743 · FIGURE 1GOLD-PLATED KOVAR HEADER TABSINGLE-CRYSTAL GERMANIUM WAFER (0.200" × 0.080")T1 (Mesa)R1 (Bulk)C1 (P-N)T2 (Mesa)
Tap any numbered pin2 Curated Callouts
Callout Pin Inspector

Select Any Numbered Pin

Click pins on the schematic or select from the list below to inspect historical specifications.

Why It Still Matters

Jack Kilby's invention of the monolithic integrated circuit is the foundational spark of the Digital Age. Today, billions of integrated circuits containing up to 100 billion transistors on a single silicon chip (such as Apple M-series, NVIDIA AI GPUs, and Intel Core processors) power all global computing, smartphones, artificial intelligence, cloud servers, medical equipment, automotive engine controls, and space exploration.

Legal Claims Decoder (25 Numbered Claims)

Compare dense legalistic claims directly with decoded plain-English functional specifications.
Claim #1Independent Master Claim
1/25
Verbatim Historical Legal Text
“1. In an integrated circuit having a plurality of electrical circuit components in a wafer of single-crystal semiconductor material, a plurality of junction transistors defined in the wafer, each transistor including thin layers of semiconductor material of opposite conductivity-types adjacent one major face of the wafer providing a base and an emitter region which overlie a collector region, the base-emitter and base-collector junctions of each of said transistors extending wholly to said one major face, a plurality of thin elongated regions of the wafer exhibiting substantial resistance to provide semiconductor resistors, the elongated regions being spaced on said one major face from the transistors, and conductive means connecting selected ones of the elongated regions to regions of selected ones of the transistors.”
Plain English Engineering Translation
A single-crystal semiconductor wafer carries several junction transistors and several thin, elongated semiconductor regions that serve as resistors. Each transistor has opposite-conductivity base and emitter layers over a collector, with both junctions reaching one major face; selected resistor regions are spaced from the transistors and conductively connected to them.
Key Protected Innovations:
Single-crystal junction-transistor arrayThin elongated semiconductor resistorsMajor-face junction termination and conductive selection
Historical Legal Impact:
This independent claim combines multiple junction transistors, spaced semiconductor resistors, surface-reaching junctions, and selected conductive connections in one wafer structure.

The Historical Bottleneck

By 1958, complex electronic computers required tens of thousands of discrete transistors, diodes, resistors, and capacitors. Hand-soldering millions of individual wire joints created the 'Tyranny of Numbers'—a barrier where systems became too large, expensive, and unreliable to function.

Why Prior Art Failed

  • •Every component was packaged in a separate metal can or ceramic tube
  • •Interconnections required manual wire routing and soldering across circuit boards
  • •Solder joint failure rates scaled exponentially with system component count
The Breakthrough Insight
“All electronic circuit functions can be created out of a single semiconductor material: bulk resistance for resistors, p-n junction depletion zones for capacitors, and diffused layers for transistors, allowing an entire computer circuit to be fabricated on a single monolithic bar of silicon or germanium.”

Patent Wars & Legal Litigations

Vs. Robert N. Noyce & Fairchild SemiconductorInfringement Challenge
Rival Claim & Defense:
Planar process with silicon dioxide passivation and evaporated aluminum interconnects
Litigation Conflict:
In January 1959, Robert Noyce at Fairchild conceived the planar integrated circuit utilizing Jean Hoerni's planar process, filing US Patent 2,981,877 in July 1959. Kilby filed this patent (US 3,138,743) on February 6, 1959. A bitter ten-year patent battle ensued over who invented the integrated circuit.
Final Resolution & Judicial Outcome:
The courts affirmed Kilby's priority on the concept of monolithic integration and Noyce's priority on planar thin-film interconnections. Texas Instruments and Fairchild wisely signed a landmark cross-licensing agreement in 1966, sharing royalties and allowing the microelectronics industry to explode globally.
Civilizational Impact
Kilby's integrated circuit made the digital revolution possible. It enabled the Apollo Guidance Computer, personal computers, the internet, smartphones, medical MRI machines, global satellite navigation, and modern artificial intelligence.
Historical Fact
Kilby built his first integrated circuit in the summer of 1958 because Texas Instruments had a company-wide mass vacation policy for all employees, but as a new hire, Kilby had not earned any vacation days and was left completely alone in the semiconductor laboratory.
Technological Lineage & Descent

The Silicon Microelectronics Revolution

From Punched-Card Tabulators to Multi-Touch Human Interfaces

The digital computation lineage that replaced mechanical gear teeth with point-contact semiconductor switches, monolithic planar circuits, personal computers, and touch glass.

1889Electromechanical Data Storage
US 395,781

Record-Card Statistical Compiler

Conductive mercury cup contacts sensing punched holes in structured card records.

1950Solid-State Transistor Origin
US 2,524,035

Bardeen and Brattain Point-Contact Transistor

Point-contact emitter/collector gold cat-whiskers modulating minority carrier diffusion.

1961Planar Monolithic Circuit
US 2,981,877

Oxide-insulated semiconductor leads

Oxide passivation, photolithographic isolation, and evaporated aluminium leads on silicon.

1964Miniaturized Solid CircuitThis Patent
US 3,138,743

Jack Kilby Monolithic Integrated Circuit

Semiconductor wafer containing active transistors and passive resistive components.

1970Interactive Spatial Input
US 3,541,541

Two-Wheel Position Indicator

Orthogonal rolling wheels driving potentiometers to translate hand motion to screen cursor.

1979Integrated Microcomputer
US 4,136,359

Wozniak Video Timing and Color Circuit

Shared-RAM timing generator enabling flicker-free color microprocessor video generation.

2001Global Information Graph
US 6,285,999

Google PageRank Algorithm

Eigenvector centrality algorithm weighting web document importance by hyperlink graph.

2009Capacitive Gestural Surface
US 7,479,949

Apple iPhone Multi-Touch Heuristics

Mutual capacitance sensor matrix resolving concurrent discrete finger touch trajectories.