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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)
ROBOT OBSTACLE DETECTION SYSTEMIntersecting Emitter and Detector Fields for Surface-Height and Wall Sensing
US 6,594,844Class: A47L 9/28 (Domestic cleaning robots; Automated floor treaters)
Inventor(s):Joseph L. Jones
Origin / Location:Acton, Massachusetts
Grant & Filing:Filed January 24, 2001 · Granted July 22, 2003

I. Historical Context & Grant Summary

US 6,594,844 protects a low-cost optical obstacle and wall detection system for an autonomous cleaning robot. An emitter's directed field intersects a photon's detector field at a finite region; the circuit uses the presence or absence of reflected signal to avoid stairs and unsuitable obstacles or to reacquire a wall with progressively smaller turning radii. The grant issued July 22, 2003 from an application filed January 24, 2001, claiming priority to provisional 60/177,703 filed January 24, 2000.

II. Core Mechanism & Scientific Principles

The patent addresses a narrower engineering bottleneck than a complete Roomba navigation policy: sonar and tactile systems were too costly, complex, power-hungry, or unreliable for a battery robot. Jones's move was to make geometry do the discrimination. A directed optical field and a detector field overlap only in a selected finite region, so a missing floor signal identifies a drop or unsuitable obstacle and a wall signal identifies a boundary.

Physical Operation:The emitter's optical power occupies a defined field of emission and the detector accepts photons only within its field of view. Their intersection is the measurement region. With a downward sensor, normal floor overlap produces a reflected, modulated signal; when a stair or too-high/low obstacle removes the floor from that region, the circuit emits an avoidance command. With wall optics, a reflected signal marks the wall and the control logic turns away, then back toward it through decreasing radii of curvature. The grant specifies the optical feedback architecture, not a particular spiral path or random-number algorithm.
Governing Formulation:
Geometric field intersection:R = F_{emission} \cap F_{view}
Modulated optical detection:S_{det}(t) = LPF\{R_{photo}[I_0 m(t)]\}
Differential-drive curvature:\kappa = \frac{\omega_r - \omega_l}{L}

III. The Granted Legal Monopoly (Key Claims)

Claim 1 (Independent)Optical obstacle triangulation

This independent claim covers a robot housing, a surface-aimed optical emitter and photon detector whose directed fields intersect at a finite region, plus detector-connected circuitry that redirects the robot when the expected floor or other surface is absent from that region.

Claim 2 (Dependent)Multi-sensor perimeter array

This dependent claim adds multiple sensor subsystems distributed around the robot housing and logic that can identify when any detector in that distributed set has failed to receive the corresponding emitter beam, making obstacle sensing redundant rather than single-point.

Claim 3 (Dependent)Integrated floor cleaning brush

This dependent claim limits the system to a robot that also carries a surface-cleaning brush. The brush is an additional cleaning organ; the claim does not turn the optical geometry into a brush design or require any particular brush shape or drive.

IV. Mechanical Organ Breakdown

Finite Optical IntersectionTerm: “field of emission” → Emitter radiation cone or angular emission field

Angled emitter and detector fields create a selected region where reflected photons are expected.

Modulated Infrared SensorTerm: “photon detector” → Photodetector or phototransistor receiver

An infrared source and tuned photon detector reject ambient optical conditions while preserving the geometry test.

Wall Reacquisition LogicTerm: “radiuses of curvature” → Successively smaller path-curvature radii

Wall detection turns away on a hit and returns along progressively smaller curvature radii.

CLASSIC PATENTS DIGITAL ARCHIVE • PERMANENT EXHIBIT ID: us-6594844-roomba
classic-patents.com/patents/us-6594844-roomba
Original USPTO PDF
Classic Patents/US 6,594,844
Internet & Modern Computing (1990–Present)Autonomous Robotics & Consumer Automation

Optical Cliff and Wall Detection for an Autonomous Cleaning Robot

US 6,594,844

Intersecting Emitter and Detector Fields for Surface-Height and Wall Sensing

Inventor(s)Joseph L. Jones
Grant DateJuly 22, 2003
Filing DateJanuary 24, 2001
LocationActon, Massachusetts
US 6,594,844 protects a low-cost optical obstacle and wall detection system for an autonomous cleaning robot. An emitter's directed field intersects a photon's detector field at a finite region; the circuit uses the presence or absence of reflected signal to avoid stairs and unsuitable obstacles or to reacquire a wall with progressively smaller turning radii. The grant issued July 22, 2003 from an application filed January 24, 2001, claiming priority to provisional 60/177,703 filed January 24, 2000.
USPTO PDF
Audio Engineering Breakdown~2 min listen

Listen to the narrated mechanical breakdown and civilizational context

Engineering Analysis & Physical Principles

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

The patent addresses a narrower engineering bottleneck than a complete Roomba navigation policy: sonar and tactile systems were too costly, complex, power-hungry, or unreliable for a battery robot. Jones's move was to make geometry do the discrimination. A directed optical field and a detector field overlap only in a selected finite region, so a missing floor signal identifies a drop or unsuitable obstacle and a wall signal identifies a boundary.
The Core Breakthrough Mechanism

The emitter's optical power occupies a defined field of emission and the detector accepts photons only within its field of view. Their intersection is the measurement region. With a downward sensor, normal floor overlap produces a reflected, modulated signal; when a stair or too-high/low obstacle removes the floor from that region, the circuit emits an avoidance command. With wall optics, a reflected signal marks the wall and the control logic turns away, then back toward it through decreasing radii of curvature. The grant specifies the optical feedback architecture, not a particular spiral path or random-number algorithm.

Interactive Real-Time Physical Simulation

Drag to rotate · Pinch to zoom · Shared controls update the displayed model
INITIALIZING THREE.JS WEBGL SIMULATION...
Finite-Region Optical Obstacle Detection.
Host-Model Telemetry/Computed Readout
Finite-Region Optical Obstacle Detection
Optical Field Overlap
Source
100%[1]
Surface in Region
Source
PRESENToptical test[1]
Context Drive Speed
Reader Scenario
0.30m/s[L/T]
Contextual Chassis Advance Rate
∂v_chassis / ∂v_command (host sensitivity)
1 (m/s) / (m/s)
Drive Speed0.3 m/s
Turn Deflection Rate1.5 rad/s
Interval ghosts
Optical overlap100.0 % · [0, 100]
Dated scenarios

Detailed Component Architecture

1Finite Optical Intersection
Angled emitter and detector fields create a selected region where reflected photons are expected.

The source geometry uses the overlap of two fields rather than a raw brightness threshold: R=Femission∩FviewR = F_{emission} \cap F_{view}. A nominal floor or wall occupies R; a changed height or boundary removes it and changes the detector output.

19th-C. Term: field of emissionModern: Emitter radiation cone or angular emission field
2Modulated Infrared Sensor
An infrared source and tuned photon detector reject ambient optical conditions while preserving the geometry test.

The preferred embodiment modulates the infrared emitter at several kilohertz and tunes the detector to that frequency. The detector circuit amplifies, rectifies, and thresholds the selected-band signal before sending a logic output to the robot controller.

19th-C. Term: photon detectorModern: Photodetector or phototransistor receiver
3Wall Reacquisition Logic
Wall detection turns away on a hit and returns along progressively smaller curvature radii.

The controller uses the detector state as feedback. When the wall occupies the intersection region it turns away; after the wall leaves, it turns back toward the wall and decreases the radius of curvature until reflection returns. This is a bounded geometric behavior, not a claim to statistical floor coverage.

19th-C. Term: radiuses of curvatureModern: Successively smaller path-curvature radii
Engineering Principles & Equations

Governing Equations & Engineering Principles

Authored explanation paired with its stated mathematical relation

Finite Emitter / Detector Intersection & Redirect Condition

Optical Obstacle DetectionClaim 1
Mathematical Governing Law
Terms:
Plain English DecoderHover or tap any highlighted phrase
The finite is where the directed overlaps the ; the circuit commands a when the expected does not occupy that region.
R\mathcal{R}
Finite Optical Test Region
Geometric intersection of the emitter and detector fields
Region

The claim makes this finite overlap region the place where the circuit tests for the expected floor, wall, or obstacle surface.

Physical Principle & Engineering Insight

US 6,594,844 claims the optical geometry and its redirect circuit. The surrounding room path is useful context but is not presented as a patented global-coverage law.

Historical Context: The grant makes a low-cost finite optical intersection do the obstacle discrimination that more elaborate ranging hardware would otherwise perform.

Geometric field intersectionAuthored Principle 1
Stated relationR=Femission∩FviewR = F_{emission} \cap F_{view}
The source's sensor does not infer distance from a generic intensity law. It selects a finite overlap region of two optical fields and tests whether the expected floor or wall occupies that region. The patent gives this region as the design variable for rejecting stairs, unsuitable obstacles, and reflectivity-dependent errors.
Modulated optical detectionAuthored Principle 2
Stated relationSdet(t)=LPF{Rphoto[I0m(t)]}S_{det}(t) = LPF\{R_{photo}[I_0 m(t)]\}
The preferred circuit modulates the infrared source at a several-kilohertz frequency, amplifies the photodetector signal, blocks DC, detects a peak, and compares it with a reference. The formula is a presentation of the described signal chain, not a numerical performance claim.
Differential-drive curvatureAuthored Principle 3
Stated relationκ=ωr−ωlL\kappa = \frac{\omega_r - \omega_l}{L}
The figures and description show a cleaning robot changing path curvature in wall following. This kinematic relation describes how unequal wheel rates create curvature, while the claim's distinctive limitation is the detector-driven sequence of decreasing radii, not a fixed wheel geometry.

Interactive Schematic Sheet (Fig. 1)

FIG. 1 is the source schematic of robot 10 approaching downward stair 12.

1.00x
US 6,594,844 · FIG. 1
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

The durable lesson is source-bounded sensor design: an inexpensive emitter, detector, collimator, modulation circuit, and explicit control response can handle stairs and room boundaries without sonar or a global map. Later domestic robots may add lidar, cameras, or learned maps, but this patent's optical overlap and wall-reacquisition ideas remain legible as a low-cost safety and boundary-sensing pattern.

Legal Claims Decoder (20 Numbered Claims)

Compare dense legalistic claims directly with decoded plain-English functional specifications.
Claim #1Independent Master Claim
1/20
Verbatim Historical Legal Text
“A robot obstacle detection system comprising: a robot housing which navigates with respect to a surface; a sensor subsystem having a defined relationship with respect to the housing and aimed at the surface for detecting the surface, the sensor subsystem including: an optical emitter which emits a directed beam having a defined field of emission, and a photon detector having a defined field of view which intersects the field of emission of the emitter at a finite region; and a circuit in communication with the detector for redirecting the robot when the surface does not occupy the region to avoid obstacles.”
Plain English Engineering Translation
This independent claim covers a robot housing, a surface-aimed optical emitter and photon detector whose directed fields intersect at a finite region, plus detector-connected circuitry that redirects the robot when the expected floor or other surface is absent from that region.
Key Protected Innovations:
Optical obstacle triangulationDefined intersection volumeDynamic deflection circuit

The Historical Bottleneck

The specification identifies a long-felt need for battery-powered autonomous dusting, mopping, vacuuming, and sweeping robots. It says available sonar systems were too complex or expensive, while tactile sensors were inefficient, and the robot still had to distinguish stairs and unsuitable obstacles from traversable thresholds.

Why Prior Art Failed

  • •Sonar obstacle and wall sensors described as too complex or expensive for a battery-operated cleaning robot
  • •Tactile sensors described as inefficient for reliable obstacle and wall detection
  • •Single intensity thresholds confounded by surface reflectivity and specular scattering
The Breakthrough Insight
“The source's breakthrough is geometric calibration: intersect the detector's field of view with a directed emitter field at a finite region, then test whether the floor or wall occupies that region. Angled collimators reduce reflectivity and specular-scattering errors, and the wall controller returns through decreasing radii of curvature.”

Patent Wars & Legal Litigations

Vs. Electrolux (Trilobite) & SharkNinja / bObsweepInfringement Challenge
Rival Claim & Defense:
Electrolux commercialized the Trilobite in 2001 using ultrasound acoustic pinging, while later competitors (SharkNinja, bObsweep) attempted to copy Roomba's optical wall-following and cliff-detection sensors.
Litigation Conflict:
iRobot brought patent infringement actions before the US International Trade Commission (ITC Investigation No. 337-TA-1057) and federal court against multiple manufacturers, asserting US Patent No. 6,594,844 and companion obstacle navigation patents.
Final Resolution & Judicial Outcome:
The ITC issued exclusion orders barring infringing robotic vacuums from entering the United States, and competitors settled by licensing or redesigning sensor geometries.
After the Grant
The patent issued July 22, 2003 as US 6,594,844 B2. This record makes no unsupported claim about later litigation, sales, or market share; those belong to separate documented sources.
Civilizational Impact
Within the boundaries of this grant, the contribution is a low-cost optical safety and boundary-sensing subsystem for autonomous cleaning robots. It does not by itself establish a global map, an expanding spiral, or a randomized coverage guarantee.
Further Context
  • The specification gives a preferred cliff-sensor geometry with 22 mm by 53 mm housing dimensions, 3 mm collimator tubes, a 60° tube angle, and a 29.00 mm intersection region.
  • For wall detection it describes parallel-to-floor optical axes intersecting at about 80° and a volume approximately 2.6 inches ahead of the robot shell when travelling parallel to a wall.
Technological Lineage & Descent

Robotic Manipulation & Kinematic Degrees of Freedom

From Nuclear Hot-Cell Teleoperation to Parallel Delta Delta Manipulators

The kinematics and robotics lineage that transformed remote mechanical linkages into programmable magnetic-drum arms, selective-compliance SCARA robots, and high-speed delta mechanisms.

1958Bilateral Force-Reflecting Teleoperation
US 2,846,084

Goertz Force-Reflecting Master–Slave Manipulator

Position-error servomechanisms returning remote contact force feedback to human operator.

1961Programmable Robotic Manipulator
US 2,988,237

Devol Programmed Article-Transfer Controller

Magnetic recording drum storing multi-axis coordinate trajectories for playback.

1963Automated Visual Inspection
US 3,081,379

Lemelson Machine Vision & Automated Video Inspection

Video scanning raster signal comparison against reference templates for parts inspection.

1965Continuous Hydraulic Articulation
US 3,212,649

AMF Versatran Programmed Manipulator

Hydraulic servo actuation delivering coordinated multi-axis industrial transfer movements.

19786-DOF Anthropomorphic Arm
US 4,068,536

Stackhouse Intersecting-Axis Robot Wrist

Electrically actuated revolute joints mimicking the human shoulder, elbow, and 3-axis wrist.

1978Remote-Center Passive Compliance
US 4,098,001

Watson Passive Remote-Center Compliance End Effector

Geometric elastic shear pads placing the center of compliance at the tip of the inserted peg.

1982Selective Compliance (SCARA)
US 4,341,502

Makino Four-Link SCARA Assembly Robot

Rigid vertical axis combined with compliant horizontal planar articulation for assembly.

1985Automatic Robotic Tool Changer
US 4,512,709

Milacron Robot Toolchanger: Common Base, Pins, and Wedge Lock

Precision kinematic docking interface transferring pneumatic, electrical, and mechanical tools.

1990High-Speed Parallel Delta Kinematics
US 4,976,582

Clavel Delta Parallel Robot

Three closed-loop parallelograms moving a lightweight traveling plate with high acceleration.

2003Autonomous Mobile Spatial NavigationThis Patent
US 6,594,844

Optical Cliff and Wall Detection for an Autonomous Cleaning Robot

Dual differential drive wheels and sensor-guided state machine traversing unmapped rooms.