Invalidity dossier
US 4821034
Added 9/23/2026, 2:52:53 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview: US4821034A
Title: Digital exchange switch element and network
Patent Number: US4821034A
Inventors: Terry M. Anderson; Robert S. Cornelius
Original Assignee: Ancor Communications Inc. (later listed as QLogic LLC)
Application Number: US07/011,842
Priority/Filing Date: 1987-02-06
Publication (Grant) Date: 1989-04-11
Legal Status: Expired – Lifetime (anticipated expiration 2007-02-06)
Purpose: The invention relates to information exchange and communications networking. More specifically, it concerns a method and system for passing analog or digital information from one of a large number of sources to any one of a large number of destinations through space-division switching.
Plain-Language Scope: The patent describes a switch element and network that establish a private transmission path between an input and output on request, use it exclusively, then release it. It contrasts space-division switching with time-division switching, noting that space-division switching is relatively indifferent to the kind of use made of a connection, whereas time-division switching requires clock synchronization, common data formats, and common transmission speeds. The background discusses crossbar switches as an early space-division implementation—an M×N crosspoint array where intersections form crosspoint switches that can connect any inlet to any outlet through a single crosspoint connection. The provided excerpt describes the field and background only; it does not set out the claims or the specific novel structure.
What the excerpt does not establish: The supplied text does not include the claims, the detailed description of the preferred embodiment, the abstract, or the figures. It therefore does not establish the specific claimed switch element architecture, the network topology, the transfer/buffering mechanisms (beyond keyword frequency), or the precise scope of the invention. Dates are as listed in the source metadata.
Source: https://patents.google.com/patent/[US4821034](/patent/US4821034)/en
Generated 10/1/2026, 9:51:53 PM
Cases on file (0)
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Litigation summary
Past and pending lawsuits — plaintiffs, defendants, jurisdictions, outcomes, and notable rulings.
Proceedings on file (0)
All PTAB activity →AIA trial proceedings (IPR / PGR / CBM) filed at the USPTO Patent Trial and Appeal Board against this patent. Sourced from the USPTO Open Data Portal and refreshed every six hours; each proceeding number deep-links to the PTAB E2E docket.
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.