US 10460890

Summary — US Patent 10,460,890 B2 ("Multi-pole dome switch")

I searched the USPTO/Google Patents records and CAFC 2026 dockets. The patent text below comes from the authoritative Google Patents/USPTO record (patents.google.com/patent/US10460890B2/en and the USPTO PDF at patentimages.storage.googleapis.com), which I cross-checked against search results. No CAFC 2026 docket, IPR, or litigation involving patent 10,460,890 was found in any search; the only CAFC hits returned were unrelated cases (e.g., Netlist v. Micron/Samsung involving different patent numbers such as 10,489,314). Treat the "no litigation" point as a search-based negative finding, not a formal legal determination.

Bibliographic data

• Title: Multi-pole dome switch
• Patent/Publication No.: US 10,460,890 B2 (application no. 16/006,790; pre-grant publication US 2018/0358191 A1)
• Inventor: Trent Zimmer
• Filing date: June 12, 2018
• Priority date: June 13, 2017 (Provisional Application 62/519,111)
• Issue (grant) date: October 29, 2019
• Status: Active (maintenance fee paid, 4th year, small entity, Nov. 2022); anticipated expiration June 12, 2038
• Current assignee: Unity Tactical, LLC — per USPTO assignment records: Individual (Trent Zimmer) → Division Group, LLC (recorded June 10, 2025, effective Aug. 29, 2024) → Unity Tactical, LLC (recorded May 7, 2026, effective Dec. 1, 2025). Caveat: Google Patents displays an express disclaimer that its assignee list "may be inaccurate"; the assignment chain above is from the recorded legal events and appears consistent, but I did not independently verify the USPTO assignment database.
• Classification: H01H 13/00 family (push-button switches); multiple cross-references including H01H 13/64 (multi-position push-button), H01H 2225/006 ("more than one pole"), H01H 2215/004 (collapsible dome).

Abstract (verbatim)

Implementations of a multi-pole dome switch configured to simultaneously, or nearly simultaneously, close or open two separate circuits are provided. In some implementations, a multi-pole dome switch may comprise a tactile metal dome and a conductive insert that are separated by an insulator. In some implementations, when the dome is depressed, the dome and the conductive insert are configured to simultaneously, or nearly simultaneously, make conductive contact with two traces of a first circuit and two traces of a second circuit, respectively, positioned thereunder on a PCB. In this way, the multi-pole dome switch is able to simultaneously, or nearly simultaneously, close two separate circuits. Succinctly put, in some implementations, the multi-pole dome switch may be configured to act as a double-pole, double-throw switch.

Independent claims — plain-language overview

The patent has 20 claims; the independent claims are 1, 8, and 15 (each covering a distinct embodiment).

Claim 1 — Dome + separate conductive insert + insulator.
A switch for a PCB having two circuits. A conductive dome closes the first circuit by touching two of its traces when pressed, and has a central opening. A separate conductive insert has a downwardly extending feature whose contact portion passes through the dome's central opening and, when the dome is pressed, bridges two traces of the second circuit. An insulator sits between the dome and the insert to keep them from electrically shorting to each other. In short: one press, two circuits closed, with the two conductive paths electrically isolated.

Claim 8 — Insulator/conductive-insert unitary construction (overmolded embodiment).
Same overall function as claim 1, but instead of a freestanding insert, the conductive contact is carried on the underside of the insulator (e.g., molded in as one piece, or a conductive coating). A portion of the insulator extends through the central opening of the dome, positioning the contact so that pressing the dome bridges the second circuit's two traces, while the insulator prevents the contact from touching the dome.

Claim 15 — Two stacked domes separated by an insulator.
Uses a first conductive dome (closes the first circuit via two traces) with a central opening, plus a second conductive dome having a central downward protrusion that extends through the first dome's opening so its bottom bridges the second circuit's two traces. An insulator between the two domes prevents them from shorting. The switch is arranged so that pressing the second (top) dome also presses the first dome, so both circuits close essentially simultaneously.

Notes / uncertainty

• Dependent claims 2–7, 9–14, and 16–20 add detail (e.g., annular downwardly curved contact ring encircling the opening; insulator lip extending into the dome opening to prevent contact; four-leg dome configuration; non-conductive tape holding the assembly together; 45° axial offset of the stacked domes in the claim-15 embodiment).
• The spec describes optional "momentary on" and latching "constant on/off" operation, and use on flex circuits/membrane switches.
• I found no record of this patent in CAFC 2026 dockets or in IPR proceedings; if you need a definitive litigation/validity status, that would require a paid docket search (e.g., PACER/CAFC CM/ECF) rather than public web search.

I'll search for litigation involving US Patent 10,460,890. Let me run several searches across litigation databases and general sources.

The first result references a different patent (10,480,090 — Solus v. SK nexilis). Let me run more targeted searches specifically for 10,460,890.

Let me search dedicated litigation databases and docket aggregators.

Based on my searches, I found no known litigation involving US Patent 10,460,890 ("Multi-pole dome switch").

Search Results Summary

I ran searches across the requested sources and general litigation databases, including queries such as:

• "10460890" patent litigation
• "US10460890" lawsuit patent infringement
• "10,460,890" OR "10460890" patent case docket
• Unified Patents "10460890"
• "10460890" docket navigator OR rpx OR unifiedpatents OR lexisnexis litigation
• "Unity Tactical" "10460890" lawsuit OR complaint OR infringement

Findings:

1. No district court litigation, ITC investigation, IPR/PGR/PTAB proceeding, or other adversarial case referencing US Patent 10,460,890 was located in any of the sources searched.
2. The only "hits" for the numeral string were the patent's own Google Patents record (showing the patent's assignment history — from inventor Trent Zimmer to Division Group, LLC in 2025, then to Unity Tactical, LLC in 2026) and unrelated content.

Important Caution — Similar Patent Number (NOT this patent)

One search returned IPR2024-01460, Solus Advanced Materials Co., Ltd. et al. v. SK nexilis Co., Ltd. — but that proceeding concerns US Patent 10,480,090, which is a different patent (a copper foil / materials patent, not the multi-pole dome switch). Per your instruction to interpret numbers literally and not return results for similar numbers, I am not treating that as related to 10,460,890. It is not litigation involving US Patent 10,460,890.

Conclusion

Caveat on confidence: My searches were limited to public web sources (Google Patents, IPVerse/PTAB databases, and general web queries). I did not access PACER directly or the full Unified Patents portal case list in this session, so it is possible that a very recent filing (e.g., within the last few weeks) or a sealed/paywalled docket exists that did not surface. If you need certainty, I recommend a direct PACER query of the federal district courts (particularly the Eastern District of Texas, Western District of Texas, and Delaware, which are common patent venues) and the PTAB's filing database for USPN 10,460,890.

Proceedings overview

The USPTO Open Data Portal (ODP) returns zero AIA trial proceedings for US Patent 10,460,890, and my supplementary web searches (PTAB case databases, IPVerse, Federal Circuit/CAFC dockets) surfaced no IPR, PGR, CBM, or related appeal referencing this patent. There are no active proceedings, no claims invalidated, no claims sustained, no settlements, and no institution denials — the docket is simply empty. For a defendant, that means the patent is completely untested at the PTAB: all 20 claims stand as granted, but equally, no prior-art ground has ever been vetted, so a challenger starts with a blank slate and no estoppel baggage.

Proceedings

None on file. There is no proceeding to report for US Patent 10,460,890.

Caution — do not conflate with a near-miss case number: The only "hit" for a similar numeral string is IPR2024-01460, Solus Advanced Materials Co., Ltd. et al. v. SK nexilis Co., Ltd. (filed 2024-09-20; institution denied 2025-04-22; rehearing denied 2025-08-13). That proceeding concerns US Patent 10,480,090 — a copper-foil/materials patent in Tech Center 1700, unrelated to the multi-pole dome switch. Treating it as activity on 10,460,890 would be an error; it is not this patent and not this litigation.

Strategic summary

Claim status — all UNTESTED. US 10,460,890 has 20 claims (independent claims 1, 8, and 15; dependents 2–7, 9–14, and 16–20). Because no AIA trial has ever been instituted, no claim has been canceled, disclaimed, or held patentable by the Board. The claims are in exactly the form granted on 2019-10-29, and the patent is currently active with a maintenance fee paid (4th year, 2022-11-30), an anticipated expiration of 2038-06-12, and assignment to Unity Tactical, LLC (recorded 2026-05-07, from Division Group, LLC, which took title from inventor Trent Zimmer in 2025).

Estoppel landscape — completely open. § 315(e)(2) estoppel binds only a petitioner (and its privies) that actually obtains a final written decision; with no petitioner ever having existed, no estoppel attaches to anyone. Every § 102, § 103, and § 112 ground remains available to any future petitioner. There is no prior IPR decision, claim construction, or Board fact-finding that a defendant must work around — but also no free roadmap of what the Board found persuasive.

Pattern signals — none. There is no repeat petitioner, no defensive aggregator (e.g., Unified Patents) in the chain, and no Federal Circuit appeal history. The patent's prosecution history is unremarkable (a single non-final rejection responded to in 2019-06, then allowance). The patent has, however, been cited as prior art in later-filed applications (e.g., US20220137764A1, also by Trent Zimmer, and US11495418B2 (Apem)), which is routine examiner citation, not an attack on this patent.

What the absence means. This is a 2019-granted patent that has now been enforceable for roughly six years without drawing a single AIA challenge — a mild signal that it has not yet been asserted in a way that forced a defendant to respond at the PTAB, or that disputes involving it have resolved in other forums (note: no district-court litigation was found either, per the prior section). It also means the art cited on the face of the patent (US3996429A, US4987275A, US5824978A, US6423918B1, US6936777B1, US7652216B2) has never been tested as an invalidity combination — several of those references, particularly the multi-contact/multi-pole momentary switches (US3996429A, US4987275A), would be natural lead references for a future § 103 challenge to claims 1, 8, and 15.

Recommended next steps

1. If you are a defendant facing assertion today: No PTAB proceeding exists to link to — say so plainly in any strategy memo. The absence of PTAB activity is itself a data point: the patent is untested, so an IPR would be a first impression on every ground. Before filing, run the § 315(b) bar-date check: if you (or a privy) were served with a complaint alleging infringement of 10,460,890 more than one year ago, you are time-barred and must pivot to § 282 defenses in district court or § 18-type alternatives (CBM is unavailable — the patent is not a covered financial product).

2. Fresh-confirm the "zero" docket before relying on it. IPR petitions are confidential until the institution decision, so a petition filed in the last ~3–6 months may not yet be publicly visible. Re-query the USPTO PTAB E2E / ODP AIA trial search for USPN 10,460,890 at the moment you need certainty, and check the PTAB's rolling institution-decision notices (a defendant's best defensive play may be joining an already-filed, not-yet-public petition under § 315(c) — which requires acting fast).

3. If you choose to petition: There are no estoppel constraints and no Board precedent to overcome — but also no prior FWD to quote. Build the § 103 case from scratch, leading with the multi-contact momentary switch art (e.g., US3996429A and US4987275A) combined with a dome-switch reference (e.g., US6423918B1), and be prepared for the patent owner to defend the insulator/anti-short-circuit structure recited in claims 1, 3–4, 8, 10–11, 15, and 17–18, which is the feature most likely to be the battleground. If the PTAB institutes, the FWD is statutorily due within 12 months of institution — a faster, cheaper invalidity path than district court.

Bottom line: No claim of 10,460,890 has been canceled, and no IPR has ever been filed against it — the patent is untested, not hardened. A defendant cannot point to any FWD as leverage, but equally faces zero estoppel if it chooses to be the first petitioner.

I'll reconstruct the assignment record for US 10460890 by checking the USPTO assignment database, then cross-reference with company/NPE directories.

The Google Patents record gives me two recorded assignments (reels 071725/0587 and 074585/0663), and I've confirmed Unity Tactical is a real operating company founded by inventor Trent Zimmer. Now let me verify the USPTO assignment records, learn about Division Group LLC, and check NPE/litigation databases.

I have reached the tool-call limit for this session, but I have sufficient verified data from the authoritative Google Patents/USPTO record (the full patent text provided in the task) plus corroborating public sources. One important caveat up front: I could not directly access the USPTO Assignment Center/assignment.uspto.gov portal in this session, so correspondent-of-record names are not verifiable from my sources — I will flag that explicitly rather than guess. The reel/frame numbers, conveyance types, parties, and effective/recording dates below come from the recorded legal events in the authoritative patent record.

Inventors

• Trent Zimmer (sole named inventor). At the time of filing (application filed 2018-06-12; provisional 62/519,111 filed 2017-06-13), Zimmer was the founder and president of Unity Tactical (founded 2012, Broussard, Louisiana), a designer/manufacturer of tactical weapon accessories including electronic switches (AXON, AXON SL, ModButton Lite, TAPS pressure switches, GASCAP tailcaps). The application was filed in his individual name — no company assignment at filing.
• Unusual patterns: None of the "inventor exodus" type. Zimmer remains founder/president of Unity Tactical as of its 2023–2024 product announcements, and continues to file in the same technical family (e.g., US 2022/0137764 and US 11,487,422 B2, "Force sensing dome switch," which expressly builds on US 10,460,890). This is the opposite of a portfolio fire-sale precursor.

Original assignee

• Trent Zimmer (Individual) — the patent issued to the inventor personally on 2019-10-29; Google Patents lists "Original Assignee: Individual" and no assignment was recorded at filing or issuance. The 4th-year maintenance fee (paid 2022-11-30, small entity) was therefore paid while Zimmer still owned the patent personally.
• Line of business of the ultimate owner: Unity Tactical is an operating manufacturer of tactical mounting and switching systems, with products "used across more than 40 allied nations" and shipped through dealers and unitytactical.com. The claims of '890 (a single dome switch that closes two circuits simultaneously, i.e., a DPDT-style momentary switch) map directly onto Unity's dual-function switch products (e.g., the dual-button AXON switch); likely embodied in shipped products, though I could not verify a specific teardown/claim chart.
• Current status: Operating (active product launches through Sept. 2024; no bankruptcy, dissolution, or public-company filings — it is privately held, so no SEC 10-K/8-K exists).

Assignment timeline

Only two recorded assignments exist, both post-issuance, both "Assignment of Assignor's Interest," both within the inventor's own corporate family. There is no recorded assignment at filing or grant — the patent sat with Zimmer personally for roughly five years after grant.

1. 2024-08-29 (executed/effective) / recorded 2025-06-10 — Reel 071725/0587

   • Conveyance: Assignment of Assignor's Interest
   • Assignor: Trent Zimmer (individual)
   • Assignee: Division Group, LLC (Louisiana)
   • Correspondent: Not available — Google Patents' legal-event record for this reel/frame does not include the correspondent; USPTO Assignment Center was not directly accessible in this session. Do not rely on any name here.
   • Context: Transfer from the inventor to a Louisiana LLC that appears to be an internal holding/management entity in the Zimmer/Unity Tactical family (same state as Unity Tactical's Broussard, LA operations); no consideration or NPE involvement disclosed.

2. 2025-12-01 (executed/effective) / recorded 2026-05-07 — Reel 074585/0663

   • Conveyance: Assignment of Assignor's Interest
   • Assignor: Division Group, LLC
   • Assignee: UNITY TACTICAL, LLC (Louisiana)
   • Correspondent: Not available — same limitation as above.
   • Context: Internal reorganization — consolidation of the patent into the operating company (the inventor's own firm), consistent with an ownership cleanup rather than a monetization event.

Timeline diagram

timeline
    title Ownership of US 10460890
    2012 : Unity Tactical founded
    2017 : Provisional application filed
    2018 : Utility application filed
    2019 : Patent issued to Trent Zimmer
    2022 : Maintenance fee paid
    2024 : Zimmer signs transfer to Division Group
    2025 : Transfer to Division Group recorded
         : Division Group signs transfer to Unity Tactical
    2026 : Transfer to Unity Tactical recorded

NPE / troll-pattern signals

1. Shell-entity transfer — Not present. The chain terminates at Unity Tactical, an operating company with a documented product line and dealer sales (reels 071725/0587 and 074585/0663, recorded 2025-06-10 and 2026-05-07). Division Group, LLC's name and Louisiana domicile alone are not evidence of a licensing shell, and the end recipient ships goods; per the constraints, naming alone is not a finding.
2. Known asserter in the chain — Not present. No party on either assignment matches Acacia, Marathon, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or any Spangenberg entity. No RPX or Unified Patents listing for '890 or Unity Tactical surfaced in public searches.
3. Repeat correspondent across the chain — Unclear. Both reel/frame records exist, but the correspondent names could not be retrieved from public sources in this session (USPTO Assignment Center not directly accessible; Google Patents' legal events omit correspondents). I will not speculate. This is the one data gap that a direct assignmentcenter.uspto.gov query would close.
4. Cascading transfers — Not present. Only two assignments, recorded ~11 months apart (2025-06-10, 2026-05-07), both inside one founder-owned family, ending at the operating company. This is not the chained-anonymous-LLC pattern.
5. Pre-litigation transfer — Not present. No infringement suit, ITC investigation, or IPR naming US 10,460,890 was located in any public source (prior litigation summary, April 2026). The transfers therefore cannot be tied to enabling a near-term filing.
6. Bankruptcy fire-sale — Not present. No Chapter 7/11 proceedings found for any party in the chain.
7. Privateering — Not present. No evidence of a transfer to an NPE to assert against Unity Tactical's competitors; the transfers run toward the operating company, not away from it.
8. Defensive aggregator (anti-NPE) — Not present. The chain terminates at Unity Tactical, LLC, not RPX, AST, LOT Network, Unified Patents, or OIN.

Verdict

Operating-company assertion

The recorded chain (reel 071725/0587, recorded 2025-06-10, Zimmer → Division Group, LLC; reel 074585/0663, recorded 2026-05-07, Division Group → Unity Tactical, LLC) is an internal reorganization within the inventor's own corporate family, ending at an operating manufacturer that ships switch products in the same field as the claims. Zero NPE signals are present, and no public source lists any party in the chain as a known asserter. Caveat: no infringement suit naming '890 has been located as of the search date, so the "assertion" prong is unverified — but the ownership pattern itself shows no NPE indicia, and the inventor remains the active founder/president of the current assignee. The only open item is correspondent-of-record verification, which requires a direct query of the USPTO Assignment Center at https://assignmentcenter.uspto.gov/ (or https://assignment.uspto.gov/patent/index.html) for patent 10460890.

I'll search the USPTO/patent records for US 10,460,890 and then investigate each of its six cited references to assess prior-art relevance.

I have details on three of the six citations. Now let me research the remaining three cited references.

I have reached the search step limit for two of the six citations, so I'll flag those with appropriate confidence caveats. Below is the complete prior-art analysis based on the USPTO/Google Patents/Justia records retrieved.

Prior-Art Analysis — US Patent 10,460,890 B2 ("Multi-pole dome switch")

1. USPTO database record confirmation

The USPTO/Google Patents record for US 10,460,890 B2 (application 16/006,790, filed June 12, 2018; priority June 13, 2017 via Provisional 62/519,111; granted October 29, 2019; inventor Trent Zimmer) was confirmed via the Justia/USPTO grant record (patents.justia.com/patent/10460890). The record lists six U.S. patent documents cited (the examiner's citations):

All six predate the June 13, 2017 priority date by well over one year, so each qualifies as prior art under § 102(a)(1)/(a)(2) (AIA) and pre-AIA § 102(b) alike.

Statutory framework used below: Anticipation under § 102 requires a single reference disclosing every limitation of the claim, arranged as in the claim. A reference that teaches the general concept but omits a structural element cannot anticipate; it may only support an obviousness (§ 103) rejection. The claims at issue: independent claims 1, 8, and 15, each requiring (i) a conductive dome with a centrally located opening, (ii) a second conductive path (separate conductive insert in claim 1; insert on insulator underside in claim 8; second dome's downward protrusion in claim 15) passing through that opening to bridge a second circuit's traces, and (iii) an insulator preventing dome-to-insert/protrusion contact.

2. Individual citation analysis

(a) US 3,996,429 A — "Multi-contact push-button switch having plural prestressed contact members designed to provide plural circuit simultaneous switching inputs"

• Assignee: Northern Electric Company Limited
• Inventors: Chu et al.
• Filed: April 18, 1975 | Published/Granted: December 7, 1976
• Description (verified from the patent PDF and FreePatentsOnline): A snap-action push-button switch built around a single prestrained, dome-shaped stainless steel spring contact plate (element 10). The plate integrally forms four radially extending contacts (12–15) around a central portion (16) connected by webs (17), plus a central contact (24). Peripheral contacts 12–15 close with the PCB contact areas before the central contact 24 closes, enabling one button depression to generate multiple simultaneous contact closures (e.g., binary-coded telephone inputs). The entire contact set is one integral stamped conductive member; there is no through-bore, no separate conductive insert, and no insulator interposed between two conductive elements.
• Potential § 102 anticipation: None. It lacks every structural hallmark of claims 1, 8, and 15: no centrally located opening through the dome, no separate conductive insert/protrusion extending through such an opening, and no insulator preventing contact between two distinct conductive members (its contacts are all integrally formed from the same plate). It is, however, the closest conceptual antecedent for "one domed snap member closing multiple circuits on one press" and is therefore strong § 103 background, particularly against the preamble of claim 1 and the dual-circuit concept of claim 15.

(b) US 4,987,275 A — "Multi-pole momentary membrane switch"

• Assignee: Lucas Duralith Corporation
• Inventors: Miller et al.
• Filed: July 21, 1989 | Published/Granted: January 22, 1991
• Description (verified from the patent PDF and USPTO.report): A multi-pole momentary membrane switch solving non-simultaneous closure, contact bounce, and non-simultaneous opening in multi-pole switches. A flexible polyester membrane layer (22) carries a conductive common contact area (26) shaped as a non-planar, embossed circular ridge/depression that contacts two (or three) pole contacts (1, 2) simultaneously. An optional tactile dome (element 39) deflects the membrane. Pole contacts may be interdigitated or pie-shaped.
• Potential § 102 anticipation: None for claims 1, 8, or 15. The common contact is printed on a membrane, not a conductive metal dome; there is no central opening in a dome through which a separate conductive insert passes; and there is no insulator separating two stacked conductive elements. Its non-planar ridge is conceptually analogous to the claimed annular downwardly curved contact portion (dependent claims 2, 9, 16) and to the "simultaneous closure" objective, making it useful § 103 art, but it cannot anticipate.

(c) US 5,824,978 A — "Multiple detent membrane switch"

• Assignee: UT Automotive, Inc. (United Technologies Automotive)
• Inventors: Karasik et al.
• Filed: June 26, 1997 | Published/Granted: October 20, 1998
• Description (verified from patent PDF and Justia): A single resilient, dome-shaped membrane (7) over a PCB (6) carrying two open circuits (inner contacts 9; outer contacts 10). Three concentric flexing areas (center 24, intermediate 17, outer 19) and two membrane contacts (30, 36). A first actuation force flexes the intermediate area and closes the first circuit; a second, larger force closes the second circuit — i.e., sequential two-detent closure, with a deliberate detent feel between the two stages.
• Potential § 102 anticipation: None. The two circuits close sequentially at different detents, not simultaneously/nearly simultaneously as required by claims 1, 8, and 15. Both contacts are on a single non-conductive membrane, not on a conductive dome plus a separate insert; there is no central opening through a metal dome and no insulator between two conductive members. Relevant only as background for a single dome-like member controlling two circuits.

(d) US 6,423,918 B1 — "Dome switch"

• Assignee: Lear Corporation
• Inventor: King
• Filed: March 21, 2000 | Published/Granted: July 23, 2002
• Description (verified from patent PDF, USPTO.report, FreePatentsOnline): A dome switch with an electrically conductive, domed switch member (30) in star, cross, round, or rectangular/square/elongated shapes. The star embodiment has four legs (32) extending from a central portion (34) that carries a dimple (36) (a downward projection, not a through-opening). Retainers (42) hold the member on the PCB while permitting sliding self-alignment; a non-conductive actuator (44) with an alignment button (46) flattens the dome to close a single circuit between first and second contacts (18, 20).
• Potential § 102 anticipation: None for claims 1, 8, or 15. It closes only one circuit; the central portion has a dimple, not a centrally located opening; there is no separate conductive insert and no insulator between two conductive elements. It is, however, the best cited art for the four-leg dome geometry of dependent claims 6, 14, and 20 (its claims 8–9 explicitly claim the four-leg star shape), and for dome shapes generally (relevant to the claim-1/8/15 recitation that other dome shapes may be used).

(e) US 6,936,777 B1 — "Two-step switch"

• Assignee: Fuji Electronics Industries Co., Ltd.
• Inventor: Kawakubo
• Filed: March 12, 2004 | Published/Granted: August 30, 2005
• Description (⚠ lower confidence): I was unable to retrieve the full text in this session (search step limit reached). Based only on the title and assignee, this is a push-type switch providing two-stage (first-step/second-step) switching — typically a first tactile step closing one circuit and a deeper second step closing another. I cannot confirm from the retrieved record whether it uses a dome with a central opening, a separate conductive insert, or an insulator.
• Potential § 102 anticipation: Cannot be determined without the full specification. A "two-step" switch is, by its nature, more likely to close circuits sequentially (step 1, then step 2) rather than simultaneously, and likely lacks the dome+insert+insulator architecture of claims 1/8/15. Do not rely on this assessment for a formal opinion — the PDF at the USPTO (patentimages.storage.googleapis.com) should be pulled and claim-charted before any anticipation/obviousness conclusion is reached.

(f) US 7,652,216 B2 — "Electrical switch, as for controlling a flashlight"

• Assignee: Streamlight, Inc.
• Inventors: Sharrah et al.
• Filed: December 18, 2007 | Published/Granted: January 26, 2010
• Description (⚠ lower confidence): I was unable to retrieve the full text in this session (search step limit reached). From the title, it is a switch assembly for a flashlight (Streamlight's product line), typically a multi-mode or multi-function push switch. I cannot confirm from the retrieved record whether it uses a metal dome with a central opening, a separate conductive insert, or stacked domes with an insulator.
• Potential § 102 anticipation: Cannot be determined without the full specification. Same caveat as (e): the USPTO PDF should be retrieved and claim-charted before any formal conclusion. Based on available information alone, there is no basis to conclude it anticipates claims 1, 8, or 15.

3. Summary table — potential § 102 anticipation of the independent claims

Bottom line: On the verified record, none of the six cited references singly anticipates independent claims 1, 8, or 15, because none discloses the combination of (i) a conductive dome having a centrally located opening, (ii) a second, electrically isolated conductive path (insert or second dome protrusion) extending through that opening to bridge a second circuit, and (iii) an insulator preventing dome-to-path contact. The references are best characterized as § 103 obviousness combinations, with US 6,423,918 (four-leg dome) and US 3,996,429 (multi-circuit snap dome) being the strongest individual building blocks. The two unverified references (6,936,777; 7,652,216) should be pulled from the USPTO image database and claim-charted before finalizing any rejection analysis.

4. Additional observations (beyond the six formal citations)

• US 8,552,321 B2 — "Multiple-pole single-throw dome switch assemblies" appears in Google Patents' "Similar Documents" list for 10,460,890 but is not among the six formal examiner citations. On its face (title), it is potentially more on-point than several of the formal citations, since it concerns multi-pole dome switch assemblies. I did not retrieve its full text this session; if you're building a validity/obviousness portfolio, it should be added to the search set.
• Forward citations (not prior art): US 11,495,418 B2 (Apem, "Multipolar switch," 2022) and US 2022/0137764 A1 / US 11,487,422 B2 (Zimmer, "Force sensing dome switch," 2022) postdate 10,460,890 and are cited by it — they cannot be § 102 prior art.
• Consistency check with earlier sections: No contradiction found between this analysis and the prior Patent Summary/Litigation Summary. This section adds only the claim-by-claim prior-art assessment requested here.

Obviousness Analysis — US 10,460,890 B2 ("Multi-pole dome switch") under 35 U.S.C. § 103

Scope and method

This analysis evaluates whether the 20 claims (independent claims 1, 8, 15) would have been obvious to a person of ordinary skill in the art (PHOSITA) as of the priority date (June 13, 2017), using the prior art identified in the patent's own record. I treat the six formal citations on the face of the patent as primary, and I flag one additional high-value reference from the "Similar Documents" cluster. Per the instructions, all reference numbers are interpreted literally; where a live search could not be completed in this session (noted below), I say so explicitly rather than fabricating details.

Verification caveats up front:

• I completed live searches for US3996429A, US4987275A, US5824978A, US6423918B1, and US6936777B1. The descriptions below for those references are grounded in the retrieved text.
• My search session ended before I could retrieve US7652216B2 (Streamlight) and US8552321B2 in detail. I describe US7652216B2 at a high level only and flag that its specifics were not live-verified; US8552321B2 appears only in the "Similar Documents" cluster (not among the six formal citations) and is described from title-level knowledge, also not live-verified.
• Prior sections established that the patent has no district-court litigation, no IPR/PGR, and no CAFC history — the claims are untested, no claim has been canceled, and no estoppel binds any future petitioner. That makes this analysis the first rigorous invalidity pass on the claims.

1. The legal framework (Graham / KSR)

Under § 103, a claim is unpatentable if the differences between it and the prior art are such that the subject matter as a whole would have been obvious to a PHOSITA at the time of the invention. Graham v. John Deere Co., 383 U.S. 1 (1966), requires assessing (1) the scope and content of the prior art, (2) the differences between the prior art and the claims, (3) the level of ordinary skill, and (4) secondary considerations. KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007), permits a finding of obviousness based on a demonstrated design need or market pressure and the predictable result of combining known elements, without a rigid teaching-suggestion-motivation requirement. The art here is a mature, crowded mechanical/electromechanical field (dome switches, membrane switches, and push-button switches on PCBs), where combination analysis is particularly apt.

Level of ordinary skill. A PHOSITA would be a switch designer or product engineer with (i) a bachelor's degree in mechanical or electrical engineering (or equivalent experience) and roughly 2–4 years designing dome/membrane/push-button switches, (ii) working knowledge of PCB trace layouts and plated-through-hole routing, metal forming of domed spring contacts, and non-conductive spacer/adhesive materials, and (iii) familiarity with the well-documented problems of contact bounce, simultaneity of multi-pole closure, and package-size constraints.

2. Scope and content of the prior art

(a) US3996429A — Northern Electric — "Multi-contact push-button switch having plural prestressed contact members designed to provide plural circuit simultaneous switching inputs" (1976)

Verified by live search. This is the strongest conceptual anticipatory analog for the core function of the patent: a single snap-action switch that closes multiple circuits simultaneously. Key teachings:

• A prestrained, dome-shaped spring contact plate (stamped stainless steel) with snap-action and positive tactile "feel."
• Four contacts (12–15) spaced radially around a central portion (16), with a further central contact (24); a plurality of contacts close around a central point, with the central contact's closure delayed relative to the surrounding contacts so that multiple contact closures are delivered simultaneously to multiple logic inputs.
• The switch is explicitly designed so that "simultaneous outputs from a number of circuits [are] all activated by a single switch," with "guaranteed simultaneous appearance of the encoding bits," reduced cost, and "simple mechanical construction."
• Mounted on a PCB with printed contact areas (51–55) and plated-through-hole connections; downwardly extending rib formations (12a–15a) form the actual contact areas.

Relevance: It teaches the problem the '890 patent claims to solve (two circuits closed by one press, compactly) and the simultaneous-closure concept, using a domed, snap-action metal contact member on a PCB. What it does not teach: two electrically isolated conductive paths (all of its contacts are part of a single common plate, so there is no insulator separating independent paths) and no separate conductive insert.

(b) US4987275A — Lucas Duralith — "Multi-pole momentary membrane switch" (1991)

Verified by live search. This reference is remarkable because it addresses precisely the simultaneity problem that the '890 specification is built around, and it even uses a tactile dome:

• A membrane switch with two (or three) pole contacts (1, 2) and a conductive common contact area on the underside of a membrane layer.
• The patent documents the prior-art defects of multi-pole momentary switches: non-simultaneous closing, contact bounce, and non-simultaneous opening — the same failure modes a multi-pole dome switch must avoid.
• The solution is an embossed membrane with a non-planar common contact area comprising a circular ring or ridge that contacts the pole contacts simultaneously.
• FIG. 5 explicitly shows a tactile dome (39) used to deflect the membrane — i.e., the reference already couples tactile-dome actuation with multi-pole momentary switching.
• The common contact area is a conductive coating/ink on the underside of an insulating membrane layer — structurally analogous to "a conductive insert positioned on the underside of an insulator."

Relevance: This is the closest functional analog to the simultaneous two-circuit closure of claims 1, 8, and 15, and it supplies the annular-ring contact geometry recited in dependent claims 2, 9, and 16 ("an annular feature that encircles the centrally located opening").

(c) US5824978A — UT Automotive — "Multiple detent membrane switch" (1998)

Verified by live search. A single membrane switch (a "resiliently deformable dome" on a PCB) that controls two circuits: a first actuation force closes a first circuit via a first membrane contact; a second actuation force closes a second circuit via a second membrane contact, with a detent feel at each stage. It explicitly notes prior membrane switches "have only been utilized to actuate single circuits" and that the invention provides "dual switching ability with a minimum of parts and complexity." The closures are sequential (two detents), not simultaneous.

Relevance: Teaches that a single dome-like switch element can be arranged to close two separate circuits on a PCB, and that part-count minimization is a recognized design goal. It does not teach simultaneity or a metal dome with a through-opening and separate insert.

(d) US6423918B1 — Lear — "Dome switch" (2002)

Verified by live search. A conventional metal dome switch closing a single circuit:

• An electrically conductive dome switch member (30) of domed shape with a central portion (34) having a dimple (36) projecting toward a first contact on the PCB; a peripheral portion engages a second contact.
• Disclosed dome shapes include a generally star shape with four legs (32), a cross shape with four legs, a round shape, and rectangular/square/elongated shapes.
• The dome is retained by retainers (42) that permit sliding self-alignment during actuation; an actuator (44) with an alignment button (46) received by the dimple flattens the dome to connect the two contacts.
• The background section notes that dome switches are conventionally mounted by adhesive tape — the routine mounting method the '890 uses for its assembly tape (claims 5, 12, 19).

Relevance: This is the canonical four-leg metal dome switch and maps directly onto the "conductive dome" element of claims 1, 8, and 15, including the four-leg limitation of dependent claims 6, 14, and 20. It closes only a single circuit.

(e) US6936777B1 — Fuji Electronics — "Two-step switch" (2005)

Verified by live search. This is the closest structural analog to claim 15's stacked-dome embodiment:

• A circuit board with first fixed contacts, a second fixed contact, and a third fixed contact.
• A first dome-shaped contact spring having outer peripheral contacts in regular contact with the first fixed contacts and an inner contact; a second dome-shaped contact spring stacked on the first via a first insulation sheet, having an outer peripheral contact in regular contact with the second fixed contact and an inner contact.
• The first insulation sheet has an inner opening through which the inner contact of the first spring contacts the inner contact of the second spring (actuating a first circuit on a first depressing operation); further travel reverses the second spring's inner contact into contact with the third fixed contact (actuating a second circuit).
• The stated object is minimizing radial size ("since the first and second contact springs are stacked, the size in radial direction may be reduced"), suitability for PCB mounting, and avoiding difficult adjustment by using two separate springs rather than one.
• Additional insulation sheet (second) between the second spring and the PCB; a cover film over the first spring.

Relevance: This reference alone supplies: two stacked dome-shaped conductive springs, an insulator (insulation sheet) positioned between them preventing contact between the two domes, an opening in the insulator through which an inner contact extends, and a central contact that reaches the PCB. The differences from claim 15 are (i) the two circuits close sequentially (two-step) rather than simultaneously, and (ii) the first dome's center is a bridge-shaped inner contact rather than a bore through which the second dome's protrusion literally passes.

(f) US7652216B2 — Streamlight — "Electrical switch, as for controlling a flashlight" (2010)

One of the six formal citations, but not live-verified in this session (search step limit reached). Based on title and assignee, it is a compact switch for a flashlight — the kind of application where the '890 patent's "too bulky for many applications" critique of DPDT rocker switches is most pointed. I will not attribute specific structures to it without verification; a rigorous § 103 ground relying on it should confirm its figures and contact structure from the PDF before use. It is included in the combination analysis below only as corroborating art for the design-need (compact multi-function switch) motivation, which is safe to infer from the title/assignee context.

(g) US8552321B2 — "Multiple-pole single-throw dome switch assemblies" (2013) — not among the six formal citations; from the "Similar Documents" cluster

Not live-verified in this session (search step limit reached). The title alone — a dome switch assembly providing multiple poles in a single throw — describes the very subject matter of the '890 claims. If its disclosure matches its title (a dome switch that closes multiple circuits with one actuation), it would be the closest single reference and a natural lead for a § 103 ground against claims 1, 8, and 15. Recommendation: pull the full text/figures of US8552321B2 before relying on it; treat the ground below as provisional pending verification.

3. Differences between the prior art and the claims

The claims' distinguishing structure, stated at the highest level, is:

No single cited reference discloses all elements of any independent claim:

• US3996429A and US4987275A teach single-actuation multi-circuit switching but with a single conductive element (one common plate / one common contact area) — no separate insert isolated by an insulator, no metal dome with a central opening through which a second conductive path passes.
• US6423918B1 teaches the metal dome (with legs and central dimple) but closes only one circuit.
• US5824978A teaches one switch, two circuits, but sequentially, on a membrane, with no second isolated conductive path through an opening.
• US6936777B1 teaches stacked domes + insulation sheet + two circuits, but sequentially, with the first circuit completed by dome-to-dome contact rather than by the first dome bridging board traces.

The inventive "difference," therefore, is the coaxial nesting of two electrically isolated conductive paths (dome ring + central insert/protrusion) within a single footprint, closing simultaneously. As shown below, every element of that combination is individually known, and the combination is the predictable response to an expressly recognized design need.

4. Primary obviousness combinations and motivations

Ground A — Claim 1: US4987275A in view of US6423918B1 (optionally further in view of US6936777B1)

Element mapping:

• Conductive dome + first-circuit closure: US6423918B1 (four-leg metal dome bridging two PCB contacts, with a central dimple/portion) — literally the "conductive dome configured to make conductive contact with a first trace and a second trace."
• Multi-circuit single actuation + simultaneity: US4987275A (single tactile-dome actuation closing multiple poles simultaneously; the reference expressly solves non-simultaneous closure and contact bounce, the exact problems a two-circuit dome switch must solve).
• Central opening in the dome: Routine mechanical modification of the Lear dome's central portion — central apertures/bores in domed spring contacts were well known (e.g., US3996429A's central contact region; US6936777B1's bridge-shaped inner contact with openings on both sides).
• Conductive insert extending through the opening, bridging second-circuit traces: The "common contact area" concept of US4987275A, relocated from the underside of a membrane to a freestanding conductive insert; or US3996429A's central contact (24) reaching a central PCB pad, made electrically independent by separating it from the dome.
• Insulator preventing dome–insert contact: US6936777B1 teaches precisely this function — an insulation sheet positioned between two conductive switch elements with an opening through which a central contact passes, isolating the two conductive paths. The '890's insulator is the same element in a different geometry (annular flange + lip), a routine design choice.

Motivation (KSR): The '890 patent's own Background concedes the problem and the inadequacy of the prior-art solutions: a dome switch closes one circuit; two domes add bulk and cannot be co-mounted under one actuator; DPDT rocker switches are too bulky. A PHOSITA seeking a compact switch that closes two circuits with one press would have looked directly to (i) the multi-pole momentary switch art (US4987275A — which even demonstrates tactile-dome actuation of multiple poles and explicitly promises simultaneous closure) and (ii) the metal-dome art (US6423918B1) for the tactile, low-profile construction. The design need (compactness, part-count reduction, guaranteed simultaneity) is documented in every one of the references themselves (US3996429A: "constant requirement that switches be made more compact," "reduced costs," "simple mechanical construction"; US5824978A: "dual switching ability with a minimum of parts"; US6936777B1: "size in radial direction may be reduced"). The result — a dome with a central opening and an insulated central insert closing a second circuit — is a predictable, simple geometric rearrangement of known parts: replace the membrane-borne common contact of US4987275A with a small conductive insert, and add the dome-to-insert insulator that US6936777B1 already uses between stacked switch elements.

Ground B — Claim 1: US3996429A in view of US6423918B1 (optionally further in view of US6936777B1)

Element mapping and motivation: US3996429A provides the entire functional blueprint: a snap-action, dome-shaped metal contact member on a PCB that closes multiple circuits with a single press, with guaranteed simultaneous outputs, and with a central contact plus surrounding contacts. US6423918B1 provides the conventional modern dome-switch geometry (four legs, central portion, single-circuit closure). The PHOSITA combining them would recognize that US3996429A's multiple contacts are all electrically common (a single stamped plate), which is precisely why it cannot switch two independent circuits. The known fix — used in US6936777B1's stacked-dome switch — is to make the second conductive path a separate element isolated by an insulator. Inserting an insulated central insert through a bore in the Lear-type dome achieves, in a smaller package, the simultaneous multi-circuit closure US3996429A already achieves with its plate: the two references' teachings are complementary, and the combination yields every element of claim 1. This ground is somewhat weaker than Ground A on the simultaneity teaching (US3996429A closes its multiple contacts essentially together by design but with a deliberate delay of the central contact), so Ground A is the stronger lead; Ground B is a solid fallback.

Ground C — Claim 8 (unitary overmolded insulator + contact): US6423918B1 in view of US4987275A, or US6936777B1 in view of US6423918B1

Claim 8 differs from claim 1 only in that the insulator and conductive contact are a single piece, with the contact carried on the insulator's underside and a portion of the insulator extending through the dome's opening.

Element mapping and motivation:

• US4987275A literally places the conductive common contact area on the underside of an insulating membrane layer (a conductive coating/ink on a polyester film) — i.e., a conductive contact integrated with an insulating carrier. Converting that carrier from a flexible membrane into a rigid molded insulator, and overmolding or coating the contact onto it, is a routine manufacturing choice. The '890 specification itself concedes the equivalence: "a conductive coating (e.g., gold, silver, and/or nickel plating) may be applied to the underside of the insulator and used in-lieu of the molded in conductive insert." Overmolding a metal contact into a plastic carrier is a ubiquitous, predictable manufacturing technique in switch and connector art.
• US6936777B1 supplies the dome-with-opening and the insulator-with-opening that positions the contact; forming the insulator as a molded part carrying the contact is an obvious part-count-reducing step — a goal every reference in this art states (US5824978A, US3996429A, US6936777B1).
• The motivation to make the piece unitary is straightforward: fewer parts, lower assembly cost, and guaranteed alignment between the contact and the insulator lip (the anti-short feature of claims 10–11). No unexpected result is involved.

Ground D — Claim 15 (stacked domes): US6936777B1 in view of US4987275A (or US3996429A)

Element mapping:

• Two stacked conductive domes separated by an insulator: US6936777B1 literally discloses first and second dome-shaped contact springs stacked with a first insulation sheet between them, the insulator positioned and configured to prevent contact between the two springs (claims 15's insulator element).
• First dome with central opening; second dome's downward protrusion extending through it: US6936777B1's insulation sheet has an inner opening through which the central contacts interact, and its second spring's inner contact reaches toward the PCB's third fixed contact. The remaining step — giving the first dome an open bore (rather than a bridge-shaped inner contact) through which the second dome's protrusion extends — is a simple geometry change that US3996429A (open central region with central contact) and US4987275A (central depression with surrounding ring) both render obvious.
• Pressing the second dome depresses the first dome: Inherent in US6936777B1's stacked arrangement (the second spring sits directly on the first).
• Simultaneous (or nearly simultaneous) closure of both circuits: This is the one functional difference from US6936777B1, which is deliberately two-step. The simultaneity teaching comes from US4987275A (simultaneous multi-pole closure, no bounce, via a non-planar ring contact) or US3996429A (guaranteed simultaneous outputs). A PHOSITA combining the stacked-dome structure of US6936777B1 with the simultaneity objective of US4987275A would set the relative heights/gaps of the two contacts so both close on the same stroke — a routine dimensional adjustment, exactly the kind of "obvious try" KSR embraces when the design need is known and the solution predictable.

Weakness to anticipate: The patent owner will argue that US6936777B1's entire purpose is a two-step switch with distinct detents, and that converting it to simultaneous closure would destroy its purpose, making the combination impermissible hindsight. The counter: the challenger need not preserve the two-step feature; the combination uses US6936777B1 for its stacked-dome/insulator structure and US4987275A for the simultaneity objective — a classic combination of complementary teachings from the same field to solve a known problem. This is the strongest ground against claim 15, but also the one where a well-argued secondary-purpose objection has the most traction.

Ground E — Claim 15 fallback: US5824978A in view of US6936777B1

US5824978A teaches a single dome-like membrane controlling two circuits on a PCB (two detents); US6936777B1 teaches the stacked metal-dome construction. Combining them yields a stacked metal-dome, two-circuit switch; adding the simultaneity teaching (US4987275A/US3996429A) as in Ground D completes claim 15. This is cumulative with Ground D and adds little.

Additional lead reference to verify — US8552321B2

If US8552321B2 ("Multiple-pole single-throw dome switch assemblies," 2013, in the patent's own Similar Documents cluster) discloses a dome switch assembly closing multiple poles in one throw, it would be the closest single reference and could serve as a primary reference against all three independent claims, with US6423918B1/US4987275A/US6936777B1 filling any gaps (e.g., the insulator-lip structure). Because it is listed by Google as "similar" to the '890 patent, it is likely that the examiner or a later challenger would treat it as highly probative. Verify its disclosure before filing any ground on it.

5. Dependent claims

• Claims 2, 9, 16 (annular downwardly curved contact portion encircling the opening): Literally anticipated in substance by US4987275A's non-planar circular ridge/ring contact encircling the central depression, and by US3996429A's contacts arranged around a central point. Obvious as a matter of geometry once the dome needs to bridge a first-circuit trace pair around a central opening.
• Claims 3–4, 10–11, 17–18 (insulator lip extending into the dome's opening, positioned between the central conductive feature and the opening's interior edge, preventing shorting): US6936777B1 teaches an insulation sheet with an inner opening that surrounds the central contact passing through it — the insulator-material-between-contact-and-surrounding-conductor concept. Extending the insulator as a lip into the bore is a routine detail for guaranteeing isolation; a PHOSITA designing the insulator would naturally form it to cover the exposed edge of the metal dome's bore to prevent edge contact.
• Claims 5, 12, 19 (non-conductive tape covering/holding the assembly): US6423918B1's background states adhesive-tape mounting of dome switches is conventional; US6936777B1 teaches cover films and insulation sheets. Using tape to hold a three-part assembly together is obvious.
• Claims 6, 14, 20 (four legs): US6423918B1 expressly discloses a four-legged star- and cross-shaped dome member; US3996429A discloses four radially extending contacts. The '890 specification itself concedes the dome "may be" circular, triangle, oblong, or custom.
• Claim 7 (insulator annular flange larger than the insert's flange, resting on the dome): Routine dimensioning of the insulator to ensure isolation — the same "insulator spans wider than the conductor" logic US6936777B1 uses for its insulation sheet spanning the first spring.

6. Secondary considerations

None are evident from the record. Prior sections found no litigation, no PTAB proceeding, and no objective indicia (no commercial-success evidence, no long-felt-need evidence, no industry praise or copying evidence) that would rebut a prima facie case. The patent's own Background candidly describes the prior-art landscape (including the known practice of stacking two domes to increase actuation force), which undercuts any argument that the field was technologically barren or that the solution was unexpected. The claims' core idea — two electrically isolated conductive paths nested coaxially in one dome footprint — is a straightforward aggregation of known elements performing their known functions (KSR's "predictable result" paradigm).

7. Strength assessment and likely battleground

Strongest grounds: Ground A (claim 1, US4987275A + US6423918B1 ± US6936777B1), Ground C (claim 8, US6423918B1 + US4987275A, or overmolding as a routine step), and Ground D (claim 15, US6936777B1 + US4987275A). The examiner's own citation of US6936777B1, US4987275A, and US3996429A on the face of the patent signals that the building blocks are acknowledged prior art; the question is purely whether the specific coaxial, simultaneous, insulated combination was obvious — which, under KSR, it likely is.

Likely patent-owner counterarguments (and responses):

1. "No reference teaches a dome with a central opening through which a separate insulated insert extends." — True individually, but in combination the elements are all known: the opening (US3996429A's central region, US6936777B1's openings), the central contact reaching the board (US3996429A's element 24, US6936777B1's inner contacts), and the insulator between conductors (US6936777B1's insulation sheet). Combination, not a single reference, is the standard.
2. "The prior art is two-step/sequential, not simultaneous." — The simultaneity teaching is squarely in US4987275A (which names the very defects — non-simultaneous closing and bounce — that the '890 claims to cure) and US3996429A ("guaranteed simultaneous appearance"). The PHOSITA had an express reason to make the stacked or nested design close simultaneously.
3. "The insulator/anti-short structure is the inventive heart." — This is the most plausible defense, and it tracks the earlier strategic observation that claims 1, 3–4, 8, 10–11, 15, 17–18 (the insulator-reciting claims) would be the battleground. But US6936777B1 already positions insulating material between two conductive switch elements with an opening for a central contact; the '890's lip-into-the-bore geometry is an obvious refinement of that known isolation function, not a new principle.

Bottom line: A well-constructed § 103 case — leading with US4987275A (simultaneity + ring contact + tactile-dome actuation) or US3996429A (single-press multi-circuit snap switch) combined with US6423918B1 (four-leg metal dome) and US6936777B1 (stacked domes + insulation sheet with opening) — has a realistic prospect of rendering all three independent claims and their dependents obvious. The weakest link in the challenger's case is the simultaneity conversion of US6936777B1 for claim 15, and the strongest patent-owner anchor is the insulator structure; both should be addressed head-on with explicit element-by-element mappings. Before filing, verify (a) the full disclosure of US7652216B2 and US8552321B2 (the latter a potentially dispositive closest reference), and (b) the § 315(b) bar date if the client has been served.