Invalidity dossier
US 591055
Belleville
Added 9/21/2026, 10:42:15 AM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 591,055
Title: Burglar-Alarm
Patentee: Lewis M. Pratt, of Belleville, county of Republic, Kansas
Assignee/co-owner: One-half assigned to J. A. Boyd, of the same place
Patent date: October 5, 1897
Application filed: May 22, 1897; Serial No. 637,759; designated "(No model.)"
Classification (per source): G08B 15/00 — identifying, scaring or incapacitating burglars or intruders (e.g., by explosives)
Legal status (per source): Expired – Lifetime; anticipated expiration October 5, 1914
Source: https://patents.google.com/patent/[US591055](/patent/US591055)/en
Purpose. To provide a simple, cheap, and efficient burglar alarm attachable to a door or window frame so that opening the door or window causes a gun-cartridge to explode.
Plain-language scope. The device uses an angle-iron supporting frame whose vertical member screws to a fixed support and whose horizontal member has an opening holding an ordinary gun-cartridge. A flat plate-spring pivoted at one end to the horizontal member extends its free end over the cartridge opening and carries a pin on its underside to strike the cartridge cap. A wire trigger pivots on a vertical axis, its upper portion bent as a crank to sit beneath the raised spring and its lower portion bent into a substantially S-shaped horizontal part positioned to be moved by the closing door. A lever pivoted on the vertical member works through an opening in the horizontal member to lift the spring for setting; a stud-and-recess arrangement limits inward spring movement so the pin aligns over the cartridge. Spring rotation on its bolt exposes the opening for cartridge removal/insertion. The alarm may also be operated by a window sash, drawer, or similar movable device.
Claims. Three claims: (1) frame, spring, pin, lifting lever, and trigger; (2) the same with the trigger specifically formed as bent wire having a crank and an S-shaped lower portion; (3) a supporting-plate variant having a cartridge opening, spring, trigger, and lever pivoted in a plate opening.
What the excerpt does not establish. The excerpt is partial ("Excerpt only; consult the source for omitted text") and omits the closing attestation/witness text. It does not establish litigation, ownership transfers, validity, or prior art, and no such matters are addressed here.
Generated 10/1/2026, 10:01:15 PM
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Litigation summary
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Proceedings on file (0)
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No PTAB proceedings on file. This patent has not been challenged via IPR, PGR, or CBM. The absence is itself a signal — well-asserted patents eventually attract IPRs. The LLM analysis below may surface filings the ODP feed hasn’t indexed yet.
PTAB challenges
AIA trial proceedings at the USPTO Patent Trial and Appeal Board — IPR, PGR, and CBM. Petitioners, judge panels, claim-level invalidation outcomes from Final Written Decisions, and Federal Circuit appeals. The single most important defensive datapoint after litigation history.
Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
Earlier patents, publications, and products that may anticipate or render the claims unpatentable.
Obviousness
Combinations of prior art that suggest the claimed invention would have been obvious under 35 U.S.C. § 103.
Extensions
Patent term adjustments, term extensions, continuations, divisionals, family members, and expiration dates.
Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.