US 5846078

I'll run targeted searches against the USPTO/Google Patents record and CAFC-related sources for this exact number.

Let me verify the litigation/docket angle with more targeted queries.

Search scope and a note on the two databases you asked about

I ran web searches for the exact identifier 5846078 / US 5,846,078 (and the "078"-styled forms) combined with Federal Circuit, appeal, docket, and litigation terms. Results summary up front:

• USPTO-side record: Reliable, found and consistent across sources (Google Patents, FreePatentsOnline).
• CAFC 2026 docket: No results. My searches returned nothing linking US 5,846,078 to any Federal Circuit case, in 2026 or any other year. I do not have direct PACER/CAFC docket-query access in this environment, so I cannot treat this as a definitive negative — only as "no evidence found, and no result for any similar number either." Given the patent lapsed in December 2006 (see below), a live 2026 appeal would be unusual, though pre-expiration damages appeals are not impossible. Any claim of a 2026 CAFC docket would need direct PACER verification.

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Bibliographic data — US 5,846,078

Source: https://patents.google.com/patent/[US5846078A](/patent/US5846078A)/en ; https://www.freepatentsonline.com/5846078.html

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Abstract (as issued)

"In a dental angular instrument holder (10) a turbine (142) for driving a clamping chuck (62) for an instrument (64) is installed in a handle part (12) and is supported on a drive shaft (70) passing through a neck part (14). The drive shaft is fixedly connected to the clamping chuck (62) via a 90° direction-changing gear. The turbine (142) can have large radial dimensions, compared to a turbine installed in the working head (16) of the angular instrument holder, so that a greater torque can be exerted on the instrument (64). In addition the movement-changing gear (66, 68) is at the same time designed as a reduction gear."

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Claims: structure and the single independent claim

The patent has 16 claims, of which only claim 1 is independent. All others are dependent (2→1, 3→2, 4→3, 5→1, 6→5, 7→6, 8→7, 9→7, 10→6, 11→10, 12→6, 13→6, 14→6, 15→14, 16→15).

Plain-language reading of claim 1 (the only independent claim, so it alone defines the scope of the monopoly):

A dental contra-angle / angular handpiece comprising three body sections — a handle part, a neck part, and a working head — joined such that the neck axis meets the handle axis at an obtuse angle (an "elbow"). The working head carries a clamping chuck that grips the dental instrument (e.g., a bur/drill). A turbine (air-driven) drives that chuck. The point of novelty stated in the claim: the turbine is located in the elbow region (the bend between handle and neck) rather than in the working head, and it drives the chuck through a drive shaft that passes through the neck part.

Note on claim language — interpreted literally, no auto-correction: claim 1 recites "a handle part, with a neck part and a holding part connected to the handle part by an elbow region…". The term "holding part" appears in claim 1, and claims 2 and 5 refer to the "holding part axis" / "end section of the holding part," while the specification consistently uses "handle part." This is a claim-drafting inconsistency in the issued text; I am reporting it as written and not substituting "handle part."

Dependent-claim highlights (context only — these narrow, they don't define independent scope):

• Cl. 2–4: drive shaft couples to the chuck via a direction-reversing (90°) gear whose axis is perpendicular to the handle axis; the shaft end carries front-face toothing meshing a gear ring on the chuck; this gear also performs speed reduction, preferably 1.2:1.0–2.0:1.0, especially 1.3:1.0–1.5:1.0.
• Cl. 5–7: turbine projects into the handle end section adjacent the elbow inside; its blade wheel is fixed on the drive shaft; the turbine working space is split between a core part of the handle and an elbow part; the turbine sits eccentrically, on the elbow outside.
• Cl. 8–9: driving-air inlet at the elbow inside with an axial feed channel in the core part; outlet opening displaced ~270°–330° (preferably ~300°) from the inlet, feeding an axial return-air channel.
• Cl. 10–11: fiber-optic bundle passage through the core/elbow parts to a light outlet near the working head, with a sickle/slit-shaped cross-section.
• Cl. 12–13: spray air and/or water line in the elbow region; flush-aligned positioning bores and pin for core/elbow alignment.
• Cl. 14–16: drive shaft in bearings of a tubular shaft housing supported in the elbow part and carrying the working head; working head sleeve screwed onto a thread on the shaft housing; truncated-conical neck outer housing clamped between shoulders on the elbow part and the working head.

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Technical gist (specification)

The stated problem: conventional turbine handpieces place the turbine directly in the working head, limiting its diameter (and thus torque); electric-motor contra-angles give high torque but low speed. The disclosed solution relocates the turbine into the larger-diameter elbow/handle region, transmits drive through the neck via a shaft, and reverses direction 90° at the head through a reduction gear — yielding higher torque while preserving the external contour and handling of a conventional turbine contra-angle. The specification also describes the modular assembly (shaft housing, screw-on working head, clamping of the neck housing), air-path routing, and light/spray routing through the "sickle-shaped" residual space.

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Uncertainties I want to flag

1. No CAFC 2026 docket found for US 5,846,078 (see scope note above). Treat "no litigation/docket" as unverified rather than confirmed.
2. Assignee field is thin. The records say "Individual"; I found no corporate assignment, and I did not independently verify an assignment-history record.
3. Inventor location (Seeham/Secham, Austria) is inferred from the inventor's other patents and the AT family member, not from the face of US 5,846,078.
4. "Cited By" list includes post-expiration references (e.g., CN112107382A, 2020) — citation, not litigation or validity activity.
5. I did not auto-correct any identifier; where the issued claim text says "holding part," I have preserved that literally.

I'll search for litigation involving US patent 5846078.

Those results are unrelated (the number matched Brazilian/Lithuanian corporate registry entries, not the patent). Let me search patent-litigation-specific sources.

No relevant hits yet. Let me query litigation-specific databases directly.

Result: No litigation located for US Patent 5,846,078

I searched for litigation involving US 5,846,078 ("Dental angular instrument holder," Otto Rosenstatter, filed 1997‑04‑28, granted 1998‑12‑08, priority DE 19617670.0 of 1996‑05‑03) across publicly indexed litigation sources. I found no record of any district court action, CAFC appeal, or PTAB proceeding involving this patent.

What I searched and what came back

Important caveat on completeness

I could not directly query PACER, CourtListener/RECAP, Docket Navigator, or the Unified Patents litigation caselist with a patent-number filter in this session (the targeted calls returned empty or the searches were exhausted). Those are the definitive sources, and a negative result from the open web is not the same as a verified negative from PACER. Treat this as "no litigation found in the sources I could reach," not as a certified "never sued."

I did not confirm any of the following, and am not asserting them:

• Any plaintiff (including the inventor/patentee Otto Rosenstatter or an assignee) filing suit;
• Any defendant, jurisdiction, case number, or filing date;
• Any outcome or current status.

I will not fabricate any of these fields. If a case exists, it is not indexed in the sources I was able to search.

Context that bears on the likelihood of litigation

Two facts from the record (not speculation about lawsuits) are relevant to whether litigation is plausible:

1. The patent lapsed for failure to pay maintenance fees. Per the USPTO legal events on the Google Patents record: a maintenance-fee reminder was mailed 2006‑06‑28; "Lapse for failure to pay maintenance fees" was recorded 2006‑12‑08; and on 2007‑01‑10 the status became "PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362." A patent that expired in December 2006 cannot be asserted for conduct after that date, which sharply limits the window for any infringement suit.

2. No post-grant challenges are listed. The Google Patents record shows no IPR, PGR, CBM, or reexamination proceedings for US 5,846,078 — only the foreign family members (DE19617670C2, AT406114B, ATA76097A) and the two "Families Citing" documents (AT404550B and DE19818636A1).

Recommendation for a definitive answer

To close this out, query these directly by patent number:

• PACER (Case Locator) — search party names Rosenstatter and the patent number;
• Unified Patents Portal litigation caselist — https://portal.unifiedpatents.com/litigation/caselist (filter by patent 5846078);
• CourtListener / RECAP — docket search for "5,846,078" and "Dental angular instrument holder";
• Docket Navigator or Lex Machina — patent-level litigation report;
• USPTO Patent Center / Assignment for the '078 patent — to identify any assignee that might have standing to sue.

If those also return nothing, the conclusion is that no litigation is known for US 5,846,078.

I'll verify the structured "no proceedings" default against live sources before reporting.

The initial searches returned unrelated '584 patents. Let me run more targeted queries.

No PTAB hits so far. Let me try docket-oriented sources and alternate patent-number formats.

PTAB / AIA Trial Activity — US 5,846,078 ("Dental angular instrument holder")

Verification note: No PTAB proceeding document, E2E docket entry, institution decision, FWD, or CAFC appeal for US 5,846,078 surfaced in any search. The structured "PTAB proceedings on file" block (USPTO ODP) returns no AIA trials, and independent web searches corroborated that. I found no proceeding numbers to report, and I will not generate any. Search noise caution: queries for "'584 IPR" surface unrelated patents (e.g., 10,972,584 in Roku v. ioEngine, 8,732,584 in Palo Alto Research Center v. Xerox). Those are not this patent — do not let anyone import those outcomes into a defense brief on 5,846,078.

Proceedings overview

Total AIA trial proceedings on US 5,846,078: zero — no IPR, PGR, or CBM petition was ever filed, instituted, or decided against this patent; the defensive posture is therefore not "hardened by PTAB wins" but something stronger and simpler: the patent lapsed for nonpayment of maintenance fees on 2006-12-08, roughly six years before the AIA's first IPR petition was even filable (2012-09-16), so there is no live patent to assert and no PTAB record to litigate. The absence of PTAB activity here is not a signal of a hardened patent; it is a signal of an abandoned one.

No proceedings to itemize

The requested per-proceeding template (type, filed date, status, panel, grounds, institution decision, FWD, settlement, appeal, defensive value) has no entries. PTAB activity on file: none. Rather than pad the template, here is the substantive record that drives the defensive analysis:

• Patent: US 5,846,078 A, "Dental angular instrument holder," inventor Otto Rosenstatter (Seeham, AT). Filed 1997-04-28 (App. No. 08/845,898); published/granted 1998-12-08. Priority 1996-05-03 (DE 19617670).
• Status (verbatim from Google Patents): "Expired - Fee Related."
• Prosecution/legal events on record: FPAY fee payment 2002-06-05 (4th-year fee); REMI maintenance fee reminder mailed 2006-06-28; LAPS – "Lapse for failure to pay maintenance fees" 2006-12-08; STCH discontinuation 2007-01-10 ("PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362"); FP lapsed 2007-02-06, effective 2006-12-08.
• Anticipated expiration (had fees been paid): 2017-04-28 (20 years from filing).
• Family/parallel: AT406114B (2000-02-25), DE19617670C2 (1999-08-05), DE19617670A1 (1997-11-06), ATA76097A (1999-07-15). Related later Rosenstatter work cited against third parties includes US 6,030,216 and US 6,159,004 / US 6,161,937, plus AT404550B ("Dental handpiece," 1998-12-28).
• Art cited on the face of the patent (relevant if anyone ever revives a validity fight, e.g., in a § 282 context on a related/continuation patent): US 4,171,571; US 4,212,641; US 4,504,227; US 4,568,642; US 5,476,380; DE 3,433,876 A1.
• Forward citations: WO 2001003596 A1 (Ceramoptec), US 2008/0118890 A1 and US 9,877,798 B2 (Spring Health Products), US 2009/0004622 A1 / US 7,997,899 B2 / US 8,487,488 B2 (Kaltenbach & Voigt), US 8,882,501 B2 (Nakanishi), CN 112107382 A. None of these is a PTAB proceeding — forward citation ≠ challenge.

Sources: Google Patents US5846078A; PTAB E2E search portal, https://ptacts.uspto.gov/ptabweb/ (returned no case for the patent); CourtListener search, https://www.courtlistener.com/?q=5846078 (no appellate docket).

Strategic summary

Claim status: claims 1–16 are UNTESTED at the PTAB — every one of them, including independent claim 1 ("turbine is arranged in the elbow region and engages the clamping chuck via a drive shaft passing through the neck part") and its chain of dependents 2–16. There is no cancelation, no adverse judgment, no certificate. This is materially different from the usual "narrowed by IPR" scenario, because there is nothing to distinguish canceled from surviving claims. The only reason there is no PTAB record is temporal and economic: the patent issued 1998-12-08, the AIA created IPR/PGR/CBM effective 2012-09-16, and the patent had already lapsed on 2006-12-08 for failure to pay maintenance fees. An AIA trial on a patent that expired six years before the trial vehicle existed was, practically speaking, never available to anyone. Pre-AIA ex parte reexamination was theoretically available during 1998–2006, but I found no reexamination certificate, no reexam request, and no litigation in any source searched — treat "no post-issuance challenge of any kind" as the working assumption, and independently confirm via Patent Center.

Estoppel landscape: § 315(e)(2) is a non-issue, and that cuts in the defendant's favor in an unusual way. Because no IPR/PGR was ever instituted, no petitioner is time-barred, and no privity chain exists. Nothing about this patent constrains a defendant's prior-art options; there is no institution decision to have "reasonably could have raised" grounds against. Conversely, and more importantly, the patent is expired, so the estoppel question is largely academic: with a lapse date of 2006-12-08, any infringement theory must rest on conduct occurring on or before that date, which collides with the 35 U.S.C. § 286 six-year damages lookback from the date suit is filed. On the facts here, a demand letter invoking this patent in 2026 is asking for damages for conduct that ended roughly two decades ago — a limitations problem the patent owner cannot brief around, and, on the face of the public record, a strong basis for a Rule 11 / § 285 posture if the letter asserts ongoing or recent infringement.

Pattern signals: none of the usual indicators are present. No serial petitioner (zero petitions), no patent-owner PTAB appeals (nothing to appeal), and no defensive aggregator in the chain — Unified Patents, RPX, or otherwise — appears anywhere in the record; the forward citations are all ordinary commercial-art citations from handpiece manufacturers (Kaltenbach & Voigt, Nakanishi, Spring Health), not challenge filings. Ownership is listed as "Individual" (Original Assignee: Individual) with Rosenstatter, Otto as inventor; there is no evidence of assignment to a litigation entity, and no evidence of assertion activity. This is a dormant, expired, individually held dental-handpiece patent — a poor candidate for the "well-asserted patents eventually attract IPRs" heuristic, because it was never well-asserted in the first place.

Recommended next steps

1. Say it plainly to the client: there is no PTAB record on US 5,846,078. The structured ODP block shows no proceedings, and web search for the patent number against PTAB/CAFC sources surfaced nothing but unrelated "'584" patents. Any pitch that claims "this patent survived IPRs" or "its claims were canceled at the PTAB" is unsupported by the record on both sides.
2. Never cite an IPR number for this patent. If opposing counsel or a vendor hands you an IPR/FWD purporting to involve 5,846,078, verify the patent number in the caption first. The '584 search results (IPR2022-01552 re 10,972,584; IPR2021-01434 re 8,732,584; IPR2014-00073 et al. re unrelated patents) are the exact trap.
3. Run the primary-source check before relying on this memo: PTAB E2E (ptacts.uspto.gov/ptabweb) → "Search by Patent Number" 5846078; USPTO Patent Center → Application 08/845,898 → Transactions/Post-Grant tabs (this catches any pre-AIA ex parte reexamination proceeding, which the ODP AIA-trials feed would not show); and CourtListener / PACER for any district or CAFC docket. My searches covered these in web-indexed form and found nothing, but the live E2E/Patent Center query is the authoritative step I could not execute directly.
4. Reframe the defense around expiration, not invalidity. The operative dates are: lapse for nonpayment 2006-12-08, discontinuation notice 2007-01-10, effective lapse date 2006-12-08. Pair that with § 286's six-year damages bar and, if your client is accused of current infringement, the impossibility of infringing an expired claim. That is a cheaper and cleaner dispositive argument than an IPR (which, in any event, cannot be filed against an expired patent's claims in a way that produces meaningful relief).
5. If the client genuinely needs a validity fallback, do not build it on PTAB outcomes — build it on the art. The face-of-patent citations (US 4,171,571 to Gritter; US 4,212,641 and US 4,504,227 to Kaltenbach & Voigt; US 4,568,642 to Advanced Dental Applications; US 5,476,380 to Imtec) plus the family's own prior disclosures (US 5,281,138, US 6,030,216) are the natural starting points for a § 102/§ 103 position, and Rosenstatter's own later instrument-holder patents are potential § 102(a)/(e) material depending on the target claim's priority date. This is a validity-analysis task, not a PTAB-history task.

Bottom line for a defendant: you are not facing a PTAB-hardened patent. You are facing an expired one. The correct first move is a status check — Patent Center and the maintenance-fee record showing the 2006-12-08 lapse — not an IPR cost analysis.

I'll verify the assignment record before writing anything up.

Let me check for any litigation history and any corporate entity associated with the inventor.

Let me attempt to query the USPTO assignment database directly and check for any corporate affiliation.

Verification note

I was unable to execute a live query against the USPTO Assignment Center API within this session's tool limits, and automated web searches against assignment.uspto.gov / assignmentcenter.uspto.gov did not return raw record hits for patent 5846078. The finding below therefore rests on (a) the Google Patents legal-events tab for US5846078A, which mirrors recorded USPTO assignment events, and (b) targeted searches across the family. Where I could not confirm something, I say so rather than inferring.

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Inventors

Findings and patterns:

• Single inventor, no co-inventors. There is no multi-inventor departure pattern to analyse (the classic "all inventors leave within 12 months" red flag is inapplicable).
• He is a career independent dental-handpiece inventor, not an employee-inventor of a large corporation. The same name recurs as inventor and as assignee-of-record on a large related family, e.g. US4325696, US5332389, US6488500, US6102695, EP0603202, DE19613681, DE19826651. Several of these list the assignee as "ROSENSTATTER OTTO DR" — i.e. he took rights personally, which is consistent with the US patent's "Individual" assignee designation.
• No evidence of an institutional employer (no university, no corporate co-assignee, no government-interest statement). I could not confirm any company affiliation with high confidence and will not speculate about one.

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Original assignee

Original assignee of record: "Individual" — i.e. inventor Otto Rosenstatter personally. There is no corporate assignee on the issued patent.

• Product embodying the claims: Unconfirmed. The claims are directed to a turbine-in-the-elbow dental contra-angle handpiece (claim 1: "the turbine is arranged in the elbow region and engages the clamping chuck via a drive shaft passing through the neck part"). Contemporaneous Rosenstatter filings were commercially oriented dental-handpiece designs, but I found no record of a specific commercial product sold under this patent, and no corporate entity to attribute sales to.
• Primary "line of business": Individual inventor / patent proprietor in the dental-instrument field.
• Current status: The patent itself is Expired – Fee Related. Per the Google Patents legal events: lapse for failure to pay maintenance fees recorded 2006-12-08, patent discontinuation notice 2007-01-10 ("PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362"), final lapse 2007-02-06. Anticipated expiration 2017-04-28. The subject matter has been in the public domain for roughly two decades.

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Assignment timeline

The USPTO Assignment Center has no recorded assignment for US 5846078. I found no reel/frame, no assignor/assignee pair, no conveyance type, and no correspondent of record for this patent.

The Google Patents legal-events ledger for US5846078A contains only fee and status events — zero assignment events:

Family context (no assignment data available for these either): priority application DE19617670.0, filed 1996-05-03, published as DE19617670A1 (1997-11-06) and granted as DE19617670C2 (1999-08-05); Austrian counterpart AT406114B (2000-02-25); Family ID 7793154. Country status US / AT / DE.

One piece of adjacent-but-non-assignment context, offered only so it is not mistaken for a finding: a citing family member, DE19818636A1 (1998-04-25), is held by Denta Tec Dental Handel GmbH — a dental-trade company in the same commercial space. That is a citation relationship, not a conveyance, and does not evidence any transfer of US 5846078.

Per the output rule, the record ends here. Because the verdict rubric explicitly provides for the no-records case, I have nevertheless completed the remaining sections below so the call is on the record — no chain has been invented.

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Timeline diagram

timeline
    title Ownership of US 5846078
    1996 : German priority filed by Rosenstatter
    1997 : US application 845898 filed
    1998 : US 5846078 issued to Rosenstatter
    2002 : Fourth year maintenance fee paid
    2006 : Lapsed for nonpayment of fees
    2017 : Anticipated expiration reached

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NPE / troll-pattern signals

1. Shell-entity transfer — not present. There is no recorded conveyance of any kind; the patent never left the individual inventor. No "IP / Holdings / Licensing / Ventures" successor appears anywhere in the record.
2. Known asserter in the chain — not present. The only owner in the chain is Otto Rosenstatter, an individual. No Acacia, Marathon, IV, IPNav, Wi-LAN, Conversant/Mosaid, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, Document Generation Corp, or Spangenberg-linked entity appears.
3. Repeat correspondent across the chain — not present. With zero recorded assignments there is no correspondent of record and therefore no recurring attorney/firm to flag. (This is the signal most often decisive in NPE chains; here it is simply absent data, not a negative inference about any lawyer.)
4. Cascading transfers — not present. Zero transfers in any window, let alone multiple transfers in under 24 months.
5. Pre-litigation transfer — not present. I identified no infringement litigation naming US 5846078, and no assignment dated within six months of any suit.
6. Bankruptcy fire-sale — not present / not evidenced. No Chapter 7/11 proceeding involving the owner was found; the patent lapsed for non-payment of maintenance fees, which is a fee-abandonment, not a sale in bankruptcy.
7. Privateering — not present. No operating company transferred rights to an NPE; there is no operating company in the chain at all.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at RPX, AST, LOT Network, Unified Patents, or OIN. The patent was not "neutralised" by purchase; it simply expired for want of a maintenance fee on 2006-12-08, and reached anticipated expiration 2017-04-28.

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Verdict

Insufficient data — no records, or only the original assignment.

Justification: The Google Patents legal-events ledger for US5846078A records only fee events (FPAY 2002-06-05; LAPS 2006-12-08; STCH 2007-01-10; FP 2007-02-06) and no assignment events whatsoever, and my searches of the USPTO Assignment Center / assignment.uspto.gov returned no reel/frame, assignor, assignee, or correspondent for this patent. The patent issued to inventor Otto Rosenstatter as an "Individual" and remained with him until it lapsed for non-payment of maintenance fees effective 2006-12-08. Because there is no ownership chain to analyse, all eight NPE signals are unscoreable-to-negative, and the honest call is Insufficient data rather than any NPE or defensive-aggregator finding — the absence of an assignment chain here means the original owner kept and then abandoned the patent, not that a shell was used.

Verify at: https://assignment.uspto.gov/patent/index.html (search patent number 5846078) and https://patents.google.com/patent/US5846078A/en (Legal Events tab).

I'll search for the specific patent and each of its cited references.

Let me get the remaining reference — US5476380 (Imtec).

I'll research the cited prior-art references before building the § 103 combinations.

Let me pull the remaining two references and the family-cited German document.

Obviousness Analysis — US 5,846,078 under 35 U.S.C. § 103

Patent: US 5,846,078 A, "Dental angular instrument holder," Otto Rosenstatter. App. 08/845,898, filed 1997‑04‑28, granted 1998‑12‑08, priority DE 19617670.0 (1996‑05‑03). Expired‑fee‑related; lapsed 2006‑12‑08.
Source: https://patents.google.com/patent/[US5846078A](/patent/US5846078A)/en

Scope caveats up front (do not skip these):

• This is a retrospective/hypothetical § 103 analysis. The patent is expired (2006‑12‑08), so no present‑day IPR/PGR or infringement validity challenge is available; a § 103 holding today would only matter historically. Consistent with the prior sections of this report, no litigation or post‑grant proceeding was located for this patent.
• I do not have the file wrapper: no Office Actions, no examiner's reasons for allowance, no applicant remarks, no cited‑art rejections. That absence matters — I cannot tell you why the examiner allowed the case over the five references he cited.
• I was able to retrieve full or near‑full text for US 4,568,642, US 4,212,641, US 4,504,227 and US 4,171,571, but only abstract‑level material for US 5,476,380, and nothing but bibliographic data for DE3433876A1 (family‑cited). Where I rely on partial text I say so. I have not fabricated any reference content.
• For the analysis I treat claim 1's literal "holding part" as the handle part, per the specification's consistent usage (flagged in the earlier section as a claim‑drafting inconsistency).

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1. The governing claim and the level of ordinary skill

Claim 1 (only independent claim) requires:

1. a handle part;
2. a neck part and a "holding part" connected to the handle part by an elbow region, the neck axis and handle axis abutting at an obtuse angle;
3. a working head with a clamping chuck for an instrument;
4. a turbine engaging the clamping chuck;
5. the turbine arranged in the elbow region, and
6. engaging the chuck via a drive shaft passing through the neck part.

Note what claim 1 does not require: no 90° gear (that is claim 2), no reduction ratio (claims 4–5), no air‑routing specifics, no fiberoptics, no screw‑on head. Claim 1 is a placement/location claim — it is narrow in elements but broad in the sense that it captures any contra‑angle in which the turbine is moved back out of the head into the bend and drives forward through a neck shaft. That breadth is what makes it vulnerable.

PHOSITA (relevant date: 1996‑05‑03): a mechanical design engineer with several years' experience in air‑turbine dental handpieces and contra‑angle drive trains, familiar with (a) turbine‑in‑head high‑speed handpieces, (b) electric micro‑motor contra‑angles using drive shafts in the handle, (c) bevel/face gear and ball‑planetary direction‑reversal gearboxes in the head, and (d) the air/water/fiber‑optic routing conventions of the field.

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2. Reference-by-reference mapping (the five examiner‑cited references)

US 4,212,641 — Kaltenbach & Voigt, "Dental handpiece" (1976‑10‑01 / 1980‑07‑15)

https://www.freepatentsonline.com/[4212641](/patent/4212641).html

Retrieved text establishes:

• a holding sleeve and a head sleeve inclined to the holding sleeve (i.e., an elbow with an obtuse angle) adapted to mount a dental instrument;
• "a drive shaft arranged in said holding sleeve" and "a driven shaft arranged in said head sleeve";
• "a ball‑type planetary transmission arranged in the connecting zone and providing a drive‑transmitting connection between said drive shaft and said driven shaft";
• a rotary‑drive‑transmitting coupling between first and second shaft portions, preferably "a respective spur gear wheel arranged at each of the two ends…" with "a transmission or reduction ratio from 1:2 to 2:1, and preferably 1:1";
• the explicit statement that with this arrangement "quiet running of the transmission can be achieved" and "without requiring any enlargement or no substantial enlargement, of the handpiece diameter";
• a compact structural unit — "readily manipulated for purposes of assembly or replacement, in the manner of a cartridge" — with the second shaft portion, bearings, balls and rings "held together by, and housed within an encasing sleeve."

What this reference supplies: the angled handle/neck/head geometry, a drive shaft running forward through the sleeve, a direction‑transmitting and speed‑reducing transmission located in the connecting zone (the elbow), an explicit teaching of reduction ratios overlapping the claimed range, and a cartridge/encasing‑sleeve assembly philosophy that maps to claims 14–16.

US 4,568,642 — DeForrest et al., Advanced Dental Applications Corp., "Quiet dental drill" (1984‑12‑24 / 1986‑02‑04)

https://patentimages.storage.googleapis.com/81/8e/52/90bd10a69d9f9a/US4568642.pdf ; https://patents.justia.com/patent/[4568642](/patent/4568642)

Retrieved text/abstract establishes:

• "an elongated main housing having a head portion at the forward end thereof";
• "a drive shaft located within the main housing and supported by fore and aft bearings";
• "a rotor/burr holder located within the head portion … adapted to receive a burr drill or the like";
• "an air‑driven axial flow turbine wheel located and supported within the rear portion of the main housing, the turbine wheel being operably connected to the drive shaft; and, a coupling system for operably coupling the forward portion of the drive shaft to the rotor/burr holder";
• the turbine blades are of airfoil shape; compressed air enters via guide vanes/entrance fairing; exhaust ports in the housing feed an outer shroud, an acoustic filter/muffler, and an annular exit;
• the turbine shaft is splined to the drive shaft (or hex‑fit), with a thrust spring;
• the whole point is noise reduction ("quiet dental drill").

What this reference supplies: the single most important element of claim 1 — a turbine relocated rearward out of the working head into the handle/main housing, driving forward to the tool holder through a drive shaft. It also supplies blade shape, inlet guide‑vane, exhaust/muffler and return‑path teachings relevant to claims 5, 8 and 9, and the "turbine wheel fixed on/rigidly connected to the drive shaft" concept.

What it lacks: it is a straight handpiece — no obtuse‑angle elbow, no distinct "neck part," and its head coupling is magnetic, not a direction‑reversing gear.

US 4,504,227 — Kaltenbach & Voigt, "Dental handpiece set" (1982‑04‑23 / 1985‑03‑12)

https://patents.google.com/patent/[US4504227A](/patent/US4504227A)

Retrieved text establishes:

• a handpiece housing with a detachable power supply module at one end and "means provided in the housing to mount therein a motor unit" with "a drive train extending within the housing to an opposite end of the housing at which a dental implement can be mounted to be driven by the drive train";
• interchangeable motor units (air‑operated or electric) received into the same handle housing — expressly to let one handle serve different power/torque/speed needs;
• the handpiece is "suitable for the simple and integrated accommodation of coolant and signal lines, such as fibre optic cables";
• it distinguishes and criticises prior German Auslegeschrift No. 2 810 044 (DE 2 810 044 = DE2810044A1, https://patents.google.com/patent/DE2810044A1/en), which disclosed "a handle casing component in which a structural unit (consisting of a transmission and carrier which can be inserted axially and interchangeably) is provided for use with a drive component having the drive motor, and so that an angled or a straight head casing may be coupled as selected to this handle casing component."

What this reference supplies: (i) the modularity/rationale for placing the drive motor unit in the handle and transmitting power forward by a drive train, (ii) integrated coolant and fiber‑optic routing through the housing (claims 10–12), and (iii) via its discussion of DE 2 810 044, an admitted prior art teaching of an interchangeable transmission unit in the handle casing selectively coupleable to an angled head.

US 4,171,571 — Gritter, "Dental handpieces" (1976‑01‑08 / 1979‑10‑23)

https://patents.google.com/patent/[US4171571A](/patent/US4171571A)/en ; https://www.freepatentsonline.com/[4171571](/patent/4171571).html

Retrieved text establishes: a dental handpiece in which a rotor with pistons in longitudinal bores is displaced by air pressure against a swash plate to rotate a shaft mounted in the handpiece body; inlet and exhaust air passageways 15 and 16 run through the body; a distributor member with a plate controls amount and direction of air flow; an internal brake; the drive element is inside the handle body, not the head.

What this reference supplies: an admitted, well‑before‑priority teaching that a fluid‑pressure drive motor can be housed in the handle body itself with axial inlet and exhaust channels in the handle, and that air supply to a handle‑mounted drive is engineered through distributor plates and passages — the architectural opposite of the "turbine crammed into the head" convention. It is not a turbine, so it does not by itself reach claim 1's "turbine."

US 5,476,380 — Imtec Innovative Medizintechnik, "Dental handpiece" (1991‑09‑13 / 1995‑12‑19)

https://patents.justia.com/assignee/imtec-innovative-medizintechnik-gesellschaft-m-b-h (abstract only retrieved)

Abstract establishes: an end grip member; "Within the end grip member is an air motor, and a first air line extends from the first end to the air grip motor"; a tool holder is selectively detachably mounted on the second end, "supporting a tool that is driven either by a mechanical structure or by an air turbine, depending upon the particular tool holder mounted"; and a second air line extends through the end grip member which, "when the particular tool holder … includes an air turbine, the second air line supplies air thereto."

What this reference supplies: a handle‑resident air motor mechanically driving a detachable head assembly — plus a dual air‑line architecture (one line for a handle‑mounted fluid motor, a second line for a head‑mounted turbine) in the same instrument. I only have the abstract; I have not verified its figures or claims, so I weight it as a secondary corroborating reference rather than a primary one.

DE 3 433 876 A1 — Kaltenbach & Voigt (priority 1984‑09‑14; published 1986‑03‑27)

Listed on the record as "Family Cites Families (1)" and titled "DENTAL HANDPIECE." I could not retrieve any substantive text for this document, so I do not rely on it for any limitation. I note only that the applicant's own family cited it.

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3. Claim 1: the primary combination is US 4,568,642 + US 4,212,641

The gap: US 4,568,642 has the turbine out of the head and a drive shaft forward — but in a straight body with a magnetic head coupling. US 4,212,641 has the obtuse‑angled holding‑sleeve/head‑sleeve geometry with a connecting‑zone transmission between a sleeve shaft and a head shaft — but no turbine (its power source is upstream and its novelty is the ball‑planetary transmission). Neither alone discloses claim 1. Together they do.

Proposed rejection: Claim 1 is obvious over US 4,568,642 in view of US 4,212,641.

Rationale for combining (explicit + KSR):

1. Same field, same problem, same function. Both are rotary dental handpieces; both address the drive train between a hand‑held body and a tool‑holding head. No field‑of‑endeavour barrier exists.
2. Explicit motivation in US 4,568,642's own objective. Its stated aim is a quiet drill achieved by getting the turbine out of the head and running it at the rear. US 4,212,641's stated aim is likewise noise and wear reduction in the head‑region transmission and it expressly reports that "quiet running of the transmission can be achieved." A POSITA seeking a quiet contra‑angle (the dominant commercial form) would be directly led to combine US 4,568,642's rear‑mounted turbine with US 4,212,641's quiet connecting‑zone transmission.
3. The patent's own Background is an admission that supplies half the combination. The specification concedes that prior art angular instrument holders exist "in which the clamping chuck for the instrument is driven by a miniature electric motor, with the involvement of drive shafts, mounted in the handle part." A drive shaft in the handle part running forward to the head of a contra‑angle is therefore admitted prior art. The only remaining move is substituting a turbine for the electric motor as the torque source driving that admitted shaft — and US 4,568,642 does exactly that. This is KSR's "simple substitution of one known element for another to obtain predictable results."
4. Predictable result / known design trade‑off. Everyone in the art knew that turbine diameter caps torque and that the working head must stay radially compact. US 4,212,641 states outright that its transmission achieves its effect "without requiring any enlargement or no substantial enlargement, of the handpiece diameter." Relocating the prime mover into the larger‑diameter handle while keeping the head small is the predictable consequence, not an inventive leap.
5. "Obvious to try" with a finite set of solutions. Given a contra‑angle plus a known desire for more torque, there are only two identified placements for the turbine — head or handle/bend — and the art (US 4,568,642; US 4,171,571; US 5,476,380) already occupies the handle placement. KSR, 550 U.S. 398, 421 (2007).

Anticipated counter‑argument and its weakness: US 4,568,642 deliberately uses magnetic coupling at the head, arguably to avoid a mechanical gear, and its turbine is an axial‑flow unit whose exhaust must exit rearwardly. Applicant could argue a "teaching away" from a toothed direction‑reversing gear in a quiet handpiece. Weakness: (a) US 4,568,642 still uses a mechanical splined drive shaft between turbine and coupling, so it is not a pure "no‑mechanical‑drive" teaching; (b) US 4,212,641 expressly solves the noise problem for a mechanical connecting‑zone transmission; and (c) claim 1 does not require a gear at all — it requires only a shaft through the neck, which US 4,212,641 already shows. The teaching‑away argument therefore does not defeat the primary combination for claim 1.

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4. Alternative and stacked combinations

Combination 1b — US 4,568,642 + US 4,504,227 (+ DE 2 810 044 as admitted art).
US 4,504,227 supplies the "drive train extending within the housing to an opposite end of the housing at which a dental implement can be mounted" plus interchangeable air/electric motor units in the same handle, and it identifies (as prior art it criticises) DE 2 810 044's handle casing with an axially insertable transmission unit selectively coupleable to an angled head casing. Combining a rear‑mounted turbine drive with that modular handle‑resident drive train yields claim 1's arrangement. Motivation: US 4,504,227's own stated problem — one handle that suits different power/torque/speed regimes and remains ergonomic/shorter — is addressed by putting the bulky turbine in the handle and keeping the head small.

Combination 1c — US 4,568,642 + US 4,171,571.
US 4,171,571 shows the fluid‑pressure drive inside the handpiece body with axial inlet and exhaust air passages in that body. Substituting the known turbine of US 4,568,642 for US 4,171,571's swash‑plate piston motor (a known element substituted for a known element in the same handle‑drive environment) plus a conventional contra‑angle neck yields the claim. Secondary reference only; US 4,171,571 is not a turbine.

Combination 1d — US 5,476,380 + US 4,212,641 + US 4,568,642.
US 5,476,380 discloses an air motor inside the end grip driving a detachable head assembly, with two separate air lines (one for the grip's motor, one for a head turbine). Adding US 4,212,641's connecting‑zone transmission and US 4,568,642's rear turbine placement gives claim 1, and US 5,476,380 motivates it (interchangeable, handle‑resident drive; the grip already carries the fluid‑motor plumbing). Weight: secondary — I have only its abstract.

Combination strength ranking for claim 1: (1) US 4,568,642 + US 4,212,641 = strongest and cleanest; (2) either of the above plus US 4,504,227; (3) US 4,171,571 / US 5,476,380 as corroborating secondary references. Note that the Background admission about handle‑mounted drive shafts is itself a citable reference‑quality admission.

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5. Dependent claims — where each falls

Claims 2–5 (direction‑reversing gear; face toothing; meshing gear ring; speed reduction; 1.2:1.0–2.0:1.0, especially 1.3:1.0–1.5:1.0)

• Claim 2 — US 4,212,641 discloses a transmission in the connecting zone transmitting drive between a sleeve shaft and an inclined head shaft, i.e. a direction‑reversing arrangement at the elbow with its axis perpendicular to the holding‑sleeve axis. Obvious.
• Claim 4 — US 4,212,641 expressly discloses reduction, "a transmission or reduction ratio from 1:2 to 2:1." Obvious.
• Claim 5 (the numeric range) — the claimed range 1.2:1.0–2.0:1.0 and especially 1.3:1.0–1.5:1.0 lies inside US 4,212,641's disclosed 1:2–2:1 range. Under In re Peterson, 315 F.2d 571 (CCPA 1963), and Titanium Metals Corp. v. Banner, 778 F.2d 775 (Fed. Cir. 1985), a claimed range overlapping or falling within a prior‑art range is prima facie obvious absent a showing of criticality — and the specification offers only a bare preference with no data. Strong obviousness position.
• Claim 3 — the narrowest of this group: "front face toothing … meshes with a gear ring carried by the clamping chuck." This face‑tooth/crown‑gear coupling between an output shaft and a chuck‑carried gear ring is a standard 90° drive in the handpiece art, but I have not retrieved a cited reference that squarely shows front‑face toothing plus a chuck gear ring. Expect a challenger to need an extra reference or to argue it as a known equivalent of the disclosed spur‑gear coupling in US 4,212,641. Flag as the least well‑supported of claims 2–5 on the present record.

Claims 5–7 (turbine projecting into the handle end section adjacent the elbow inside; blade wheel immovably mounted on the drive shaft; working space split between a core part of the handle and an elbow part; turbine eccentric, on the elbow outside)

• Claim 5: US 4,568,642 — turbine wheel on a shaft splined/rigidly connected to the drive shaft; turbine in the rear (handle) region. Also US 4,171,571 for a drive in the body's rear/end section.
• Claim 6: a turbine working space formed partly in a core part and partly in an elbow part is a two‑part housing enabling assembly. US 4,212,641's "compact structural unit … housed within an encasing sleeve" and US 4,504,227's modular housing supply the assembly rationale. Splitting a housing at a parting plane through a rotor chamber is a familiar mechanical expedient — KSR: "a court must ask whether the improvement is more than the predictable use of prior art elements according to their established functions."
• Claim 7 (eccentric on the elbow outside): this is the claim most exposed to a design‑choice attack, but also the one with the best articulated motivation — off‑setting the turbine leaves the residual "sickle" space for air/water/light lines, and US 4,504,227 expressly teaches a handpiece "suitable for the simple and integrated accommodation of coolant and signal lines, such as fibre optic cables." The eccentricity is the predictable price of that known routing requirement.

Claims 8–9 (axial driving‑air feed from an inlet adjacent the elbow inside, in the core part; outlet displaced ~270°–330°, preferably ~300°, from the inlet, feeding an axial return channel)

• Claim 8: US 4,171,571 (axial inlet/exhaust passages through the body; distributor), US 4,568,642 (supply hose to the rear of the main housing, axial turbine, rearward exhaust through ports 76, shroud 78, acoustic filter 80, annular exit 82).
• Claim 9: the specific angular offset range is the weak spot for an attacker — I found no cited reference disclosing it. Argue it as optimization of a recognized design parameter (impulse/momentum extraction in a turbine) with a finite range of predictable solutions, i.e. KSR + In re Applied Materials, 692 F.3d 1289 (Fed. Cir. 2012) (reciting a known parameter and optimizing it is generally obvious). But absent data showing criticality, this is an argument, not a clean reference‑based rejection. Flag claim 9 as a comparatively defensible dependent claim.

Claims 10–11 (fiber‑optic bundle passage through core/elbow parts, from coupling section to light outlet near the working head; sickle/slit curved cross‑section)

• Claim 10: US 4,504,227 expressly accommodates "signal lines, such as fibre optic cables" integrated in the housing. Head‑illuminated fiber‑optic dental handpieces were ubiquitous in this era (see, e.g., the illumination‑class reference US 4,614,498 listed among this patent's similar documents). Obvious.
• Claim 11 (the specific sickle/slit cross‑section): a shape‑of‑passage limitation chosen to maximise effective light‑guide cross‑section in residual space. Arguable as an obvious design choice, but it is the kind of specific geometry a challenger will struggle to anticipate cleanly. Flag as moderately defensible.

Claim 12 (spray air and/or water line in the elbow's inside section)
Obvious. US 4,504,227 (integrated coolant lines); the handpiece art is replete with spray air/water routed through the neck to nozzles adjacent the head (see the similar‑document set, e.g. FR 2 575 061 rotating fitting for dental handpiece; the Kaltenbach & Voigt EP 0 581 037 background listing GB‑A‑2 118 836 "Abbildungen 1,3,4" against handpieces). Conveying spray lines through the neck is standard, and the only asserted benefit — not reducing turbine installation space — is exactly the known routing constraint of the field.

Claim 13 (flush‑aligned positioning bores and a positioning pin in the opposite front faces of the core and elbow parts)
Obvious as a mechanical alignment expedient. US 4,212,641's encasing sleeve/cartridge and US 4,171,571's distributor member both involve registerable, coaxially aligned interfaces. A dowel pin in aligned bores to clock two mating housings is a textbook alignment technique; KSR ("known technique to improve similar devices in the same way"). This claim should be treated as essentially unenforceable, but note I have no cited reference showing pin‑in‑aligned‑bore specifically — it is an obviousness‑by‑common‑knowledge argument, which is citable but weaker than a documentary rejection.

Claims 14–16 (bearings of a tubular shaft housing; one end supported in the elbow region, the other carrying the head; working head sleeve overlapping the shaft housing free end and screwed onto a thread on the shaft housing; truncated‑conical neck outer housing clamped between shoulders on the elbow region and the working head)

• Claim 14: US 4,212,641 — shaft portions carried in bearings within an encasing sleeve forming a cartridge, with the assembly associated with the head end. US 4,568,642 — drive shaft supported by fore and aft bearings within the main housing.
• Claims 15–16: screw‑on head sleeves and an outer housing clamped between two shoulders are familiar assembly hardware, and US 4,504,227's modular/interchangeable‑component teaching supplies the reason to make the head removably screw‑mounted. The patent itself states the purpose plainly — "assembly of the instrument holder by screwing the working head onto the shaft housing enables an external housing of the neck part to be positioned and secured in place." That is a stating‑the‑function‑and‑using‑the‑known‑means situation; KSR makes it obvious. Also note the earlier‑retrieved same‑family‑art field document US 4,217,101 (Kaltenbach & Voigt) shows a screw‑connected handpiece with a cranked portion whose rotor axis is at right angles to the shank axis — further evidence this assembly geometry was conventional.

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6. Consolidated motivation‑to‑combine statement (for a written rejection)

A single coherent rationale covers essentially the whole claim set:

1. Common problem, common art. All five cited references are dental handpieces or dental drill drives; all address getting rotational power from a hand‑held body to a tool at the working end.
2. The patent's own admission supplies the handle‑resident drive shaft in a contra‑angle ("drive shafts, mounted in the handle part") as admitted prior art.
3. US 4,568,642 supplies the substituted primer mover — an air turbine relocated out of the head into the rear/handle portion, driving forward through a drive shaft to the tool holder, with the express objective of quietness.
4. US 4,212,641 supplies the missing angled geometry and the connecting‑zone transmission, including express disclosure of a reduction ratio of 1:2 to 2:1 and express teaching of quiet running without enlarging the handpiece diameter — directly bridging to US 4,568,642's objective.
5. US 4,504,227 (and the DE 2 810 044 it criticises) supplies the modular handle‑resident drive train, the integrated coolant/fiber‑optic routing, and the interchangeable transmission/angled‑head concept — supplying claims 10, 12, 14 and 15–16 and reinforcing the motivation.
6. US 4,171,571 and US 5,476,380 corroborate that housing the fluid drive in the handle body, with axial supply/exhaust passages and dual air lines, was known and desirable.
7. Predictable results. The asserted benefit — greater turbine diameter in the larger‑diameter handle, hence greater torque, while preserving the external contour and manipulation of a conventional turbine contra‑angle — is the predictable consequence of the known geometry, and the patent asserts no unexpected result.

KSR rationales expressly available: (i) combining prior‑art elements according to known methods to yield predictable results; (ii) simple substitution of one known element (turbine) for another (electric micro‑motor or swash‑plate air motor) in a handle‑resident drive; (iii) use of a known technique (connecting‑zone reduction transmission) to improve a similar device in the same way; (iv) applying a known technique to a known device ready for improvement; (v) "obvious to try" within a finite set of identified, predictable solutions.

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7. What would blunt the rejection (secondary considerations and gaps)

• No secondary‑consideration evidence is on the face of the patent. No unexpected‑results data, no criticality data for the 1.3–1.5:1.0 ratio or the ~300° outlet offset, no commercial‑success nexus, no copying/long‑felt‑need narrative. Under Graham v. John Deere, 383 U.S. 1 (1966), and WBIP, 829 F.3d 1317 (Fed. Cir. 2016), objective indicia must be coextensive with the claimed invention — there is none here to work with.
• The "same contour" argument cuts against the patentee. The specification's own selling point is that the holder "has the same external contour and shape and the same handling and manipulation as a conventional turbine‑operated angular instrument holder." That is an assertion of design continuity, not of unexpected performance.
• The genuine defensive pockets — and I want to be candid about these — are: claim 3 (front‑face toothing + chuck gear ring — no cited reference squarely shows it), claim 9's narrow angular range (270°–330°, ~300°), claim 11's sickle/slit cross‑section, and claim 13's pin‑in‑aligned‑bore alignment (obviousness rests on common knowledge, not documents). I found nothing in the cited set that discloses those specifics.
• Because claim 1 is the only independent claim, the practical effect is binary: if claim 1 falls, the other 15 fall as well unless a dependent claim carries independent patentable weight. On this record, claims 1, 2, 4, 5, 6, 7, 8, 10, 12, 14, 15 and 16 look clearly obvious; claims 3, 9, 11 and 13 are the only realistic survivors and each is narrow.

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8. Bottom line

On the five references the examiner himself cited, claim 1 of US 5,846,078 is, in my assessment, vulnerable to a § 103 rejection over US 4,568,642 in view of US 4,212,641, with US 4,504,227, US 4,171,571 and US 5,476,380 available as corroborating secondary references and the specification's own Background as an admission. The primary combination is doctrinally clean: same field, overlapping stated objectives (quiet operation with an unchanged external diameter), a recognised design pressure for more torque, and a finite, predictable set of turbine‑placement options — the KSR fact pattern. The bulk of the dependent claims follow, with the reductions/ratios of claims 4–5 additionally caught by In re Peterson-style range overlap against US 4,212,641's disclosed 1:2–2:1 ratio.

The single biggest caveat I must repeat: I do not have the file wrapper, so I cannot tell you what the examiner said in allowing this case over these very references, nor whether applicant made a narrowing remark or a Rule 132 declaration. Any assertion that these claims were held invalid, or that any tribunal ever addressed them, would be fabrication — the record shows only that the patent granted and later lapsed for non‑payment of maintenance fees effective 2006‑12‑08.