US 5835366

I'll search for this specific patent number and any associated litigation.

Let me check for litigation involving this specific patent and verify assignee details.

US Patent 5,835,366 — Summary

Ground truth note: My searches located this patent on Google Patents, FreePatentsOnline, and Justia, and these are consistent with the authoritative full text provided. I did not find any CAFC 2026 docket activity tied to this patent number — see the litigation section below for what I did find.

Bibliographic data

• Patent number: US 5,835,366 (US5835366A)
• Title: "Secondary battery boost circuit"
• Inventors: Mark F. Pleso (Sharon, PA); Lee E. Leppo (Tallmadge, OH)
• Original assignee: Telxon Corporation (Akron, OH)
• Listed current assignee: Symbol Technologies LLC (Google Patents also lists "Bank One Corp," but that entry traces to a 1999 security-interest filing rather than an ownership transfer). Ownership chain: Telxon → Symbol Technologies, Inc. (2002) → Symbol Technologies, LLC (2015 change of name).
• Application number: US 08/881,773
• Priority/filing date: 1997-06-24
• Issue (publication) date: 1998-11-10
• Status: Expired – Lifetime (anticipated expiration 2017-06-24)
• Classifications: H02J 7/00; H02J 7/865; H02J 2207/20

Abstract (as issued)

"A secondary battery boost system which includes a primary power supply for a computing device, and a secondary power supply for the computing device. The boost system also includes a boost circuit operative to increase the power output of the secondary power supply applied to the computing device. Upon the output of the primary power supply falling below a level suitable for properly powering the computing device, the boost circuit feeds the computing device power from the secondary power supply. The boost circuit also boosts the power output of the secondary power supply so that the secondary power supply can be smaller and more light weight."

Technology context

The patent is directed to a portable/wireless mobile terminal (e.g., a Telxon-style bar-code scanning "PTC") that runs an Intel/Microsoft Advanced Power Management (APM) shutdown protocol. When the main battery dies before a task is saved, the terminal needs enough reserve power to complete an orderly shutdown. The invention uses a small, light, inexpensive 3.6 V Ni-Cd secondary battery whose output is boosted to ~5.2 V by a boost circuit (specifically identified as a Maxim MAZ1771) so it can substitute for the ~7.2 V main battery just long enough (~90 seconds; APM under Windows takes ~15 seconds) to finish the save/shutdown. A "wired OR" connection auto-switches between batteries without complex switching circuitry. Two voltage thresholds are used: ~5.4 V (LEVEL 1) triggers the APM shutdown, and ~5.2 V (LEVEL 2) causes the switch to the boosted secondary supply.

Independent claims (plain language)

There are four independent claims: 1, 7, 13, and 20.

Claim 1 — Secondary battery boost system (apparatus): Three elements only — (a) a primary battery acting as primary portable power supply for a computing device; (b) a secondary battery acting as backup portable power supply; and (c) a boost circuit that increases the power output of the secondary battery as applied to the computing device. This is the broadest claim; it does not itself require any switching logic or low-voltage detection.

Claim 7 — Method for facilitating a power shutdown protocol: (a) use a first cell as primary portable supply; (b) use a secondary cell as backup; (c) use a boost circuit to increase the power of the secondary cell applied to the device; wherein the secondary cell supplies power once the first cell's voltage drops below a predetermined value. Dependent claims add a low-voltage detection circuit (cl. 9), a wired-OR connection (cl. 10), sustaining an APM protocol (cl. 11), and boosting for enough time to complete the APM protocol (cl. 12).

Claim 13 — Portable computing device (apparatus): (a) a housing; (b) a first battery supported by the housing supplying power via a power supply; (c) a battery boost circuit disposed within the housing; (d) a secondary battery coupled to that boost circuit that supplies power upon the first battery's voltage falling below a predetermined value; wherein the boost circuit increases the secondary battery's power output and provides power to the device on that low-voltage condition. Dependent claims cover wired-OR coupling (cl. 17), wireless mobile terminal (cl. 18), and laptop computer (cl. 19).

Claim 20 — Method of providing power to a computing device: (a) power the device from a primary source; (b) determine when that source's output power is below a threshold power level; (c) sense the primary source to determine if output falls below a predetermined power level; (d) supply power via a secondary source through a power boost circuit when below the threshold; and (e) trigger an APM shutdown protocol when below the predetermined power level. Dependent claims add a wired-OR connection (cl. 21), that the predetermined level is greater than the threshold level (cl. 22 — i.e., two distinct thresholds as in the spec's 5.4 V vs. 5.2 V), low-voltage detection monitoring (cl. 23), and a wirelessly capable portable device (cl. 24).

Note: Claims 7 and 13 use "power/voltage" somewhat interchangeably in the specification's terms, which is exactly the ambiguity that became central in the litigation below.

Relevant litigation (actual, not 2026)

Google Patents flags litigation in Delaware District Court, case 1:08-cv-00340, which corresponds to Symbol Technologies, Inc. v. Janam Technologies LLC (D. Del.), 729 F. Supp. 2d 646 (2010). In that case the court addressed the '366 patent's "power" limitation and whether the accused Janam XM-60 boost circuit increased power (vs. merely voltage), and whether the Dobkin reference (Linear Technology Application Note 51) anticipated claim 7. The court found Janam raised a substantial question of invalidity and that Symbol had not shown a likelihood of success on infringement — i.e., a preliminary-injunction-stage ruling, not a final merits judgment.

Uncertainty / limitations of this report

• No CAFC 2026 docket activity for US 5,835,366 was found. My search for a 2026 Federal Circuit docket returned only unrelated matters (e.g., Spero v. Mercedes-Benz USA, Nos. 2025-1306/1307/1473 and 25-1470, dealing with U.S. Patent 10,894,503). The only confirmed litigation I can ground is the ~2010 Delaware action cited above. If you have a specific 2026 docket number, I could search more narrowly.
• The CAFC and district-court results are surfaced via secondary aggregators (CourtListener, freed.uscourts.gov, Google Patents); I have not pulled the official PACER/CAFC docket directly, so treat the litigation summary as high-confidence-but-not-PACER-verified.
• Assignee listing is complicated by a series of security interests (Bank One, Bank of New York, Foothill Capital, JPMorgan Chase, Morgan Stanley) that Google Patents surfaces alongside true assignments; the substantive owner of record is Symbol Technologies, LLC.

I'll research known litigation involving US patent 5835366. Let me search multiple sources.

The Google Patents page cited a Delaware case (1:08-cv-00340). Let me investigate that and related litigation.

I found a strong lead: Symbol Technologies, Inc. v. Janam Technologies LLC, C.A. No. 1:08-cv-00340 (D. Del.). Let me confirm the outcome and check for any other cases.

Known Litigation Involving U.S. Patent No. 5,835,366

I searched litigation-focused sources (including the Unified Patents litigation portal, which mirrors the "Family has litigation" flag on the patent's Google Patents page, plus PACER/CAFC-oriented results). Based on the available search results, one district court case is confirmed as asserting U.S. Patent No. 5,835,366.

Case 1 — Confirmed

Grounding: This matches the Google Patents "Family has litigation" link (Delaware District Court case 1:08-cv-00340). The docket records show:

• A complaint filed by Symbol Technologies, Inc. against Janam Technologies LLC (filing fee $350, receipt #152227), summons issued 6/9/2008.
• A "Patent/Trademark Report to Commissioner" (AO-120) in Case 1:08-cv-00340, filed 6/9/2008, listing patent 5,835,366 (holder: Telxon Corporation), along with 5,334,821 and 6,714,969 B1.
• Symbol's motion for a preliminary injunction (Doc. 6) and a proposed order (Doc. 7), both filed June 18, 2008.
• Answer deadline for Janam extended to July 14, 2008.
• Docket activity continued through late 2008 (deposition notices, opposition briefing, Rule 7.1 disclosure identifying Motorola Inc. as corporate parent of Symbol).

Outcome / current status: ⚠️ Not confirmed. The sources I retrieved show the case was actively litigated through at least late 2008 but do not include a docket entry reflecting a final judgment, stipulated dismissal, or settlement. I could not verify the terminating event, and I found no resulting Federal Circuit appeal. I will not speculate on the disposition; it should be confirmed directly against PACER for D. Del. Case 1:08-cv-00340 before being represented as fact.

Important disambiguation (per your literal-ID instruction)

A search for "1:08-cv-00340" also returns E360Insight, LLC v. Comcast Corporation, No. 1:08-cv-00340 (N.D. Ill.) — a different case (diversity/fraud), not related to the '366 patent. Do not conflate the two; the D. Del. '340 case is the relevant one.

No other litigation identified

Apart from the D. Del. case above, I found no other litigation asserting U.S. 5,835,366 in the sources searched. Notes:

• The patent's heavy forward citation list (e.g., Zebra Technologies Corp.'s US 12,306,684 B2, issued 2025) reflects patent citation, not litigation.
• I found no CAFC appeal, ITC action, or PTAB (IPR/PGR) proceeding involving the '366 patent.
• I found no evidence of PAE/NPE assertion activity on this patent — consistent with its long-expired status (filed June 24, 1997; expired/anticipated expiration June 24, 2017).

Caveat: My searches were search-engine-based and did not include a direct PACER or a full Docket Navigator/Unified Patents case-record pull. There could be additional short-lived suits that never generated indexed documents. If you need a definitive answer, I recommend a direct PACER docket pull for D. Del. 1:08-cv-00340 and a Docket Navigator/Terminal Disclaimer-style "patent litigation" report keyed to the exact number 5,835,366.

I'll verify the structured "no proceedings" default against public web sources before writing this up.

Let me run a few more targeted checks for CBM/PGR, reexamination, and any PTAB docket tied to this patent or its owner chain.

I have enough to answer. The structured "PTAB proceedings on file" block is canonical, and my independent web searches returned no IPR, PGR, CBM, or other AIA trial proceeding indexed to U.S. 5,835,366. Here is the report.

Proceedings overview

The USPTO Open Data Portal shows zero AIA trial proceedings on US 5,835,366 — no IPRs, no PGRs, no CBMs — so the breakdown is 0 active / 0 claims invalidated / 0 claims sustained / 0 settled / 0 institution-denied. There is no claim in this patent that has been canceled by the Board and no Board decision that a defendant can cite as a sword. The bottom-line defensive posture is therefore not "the patent has been hardened by surviving IPRs," and it is also not "the claims are dead." It is the third thing, and the one that matters here: the patent has never been tested at the PTAB at all, and it is now expired (anticipated expiration 2017-06-24), which changes the calculus far more than any Board ruling would have.

Because there are no proceedings to enumerate, the per-proceeding template is intentionally empty; I've replaced it with the nearest-thing-to-a-proceeding analysis (the only validity contest this patent ever saw, which happened in district court) plus the strategic picture.

No AIA proceeding exists (verified)

• Type: N/A
• Filed: N/A
• Status: No proceedings on file (USPTO ODP). Corroborated by web search: queries keyed to the patent number plus "IPR / PTAB / CBM / PGR" returned no petition, no institution decision, no FWD, and no termination for this patent.
• Judge panel / Petition grounds / Institution decision / FWD / Settlement / Appeal: None — there is nothing to report. I will not invent a proceeding number or panel.
• Reexamination / reissue: I found no ex parte reexamination, supplemental examination, or reissue record for the '366 patent. I cannot rule this out definitively without a direct USPTO Public/PatentCenter file-history pull, so treat "no reexam" as high-confidence-but-unverified.
• Defensive value: The absence is the signal. See the strategic summary below — for this patent, the fact that no IPR was ever filed is best explained by timing (see below), not by the patent being unusually strong.

The one validity contest that did occur (district court, pre-IPR era)

The only known attack on the '366 claims was in the co-pending Delaware case already identified in the litigation section — Symbol Technologies, Inc. v. Janam Technologies LLC, C.A. No. 1:08-cv-00340 (D. Del.) — and it predates PTAB availability (AIA trials began 2012-09-16), so it could not have generated a Board proceeding even in principle. What is publicly grounded from that case:

• Claim construction of "power" (Claim 7): In the 2009 claim-construction ruling, the court overruled the Magistrate Judge's tentative construction that "power" means "voltage" and instead construed "power" as "the rate at which energy is transferred, calculated by multiplying electric current times voltage." Symbol Techs., Inc. v. Janam Techs. LLC, 605 F. Supp. 2d 618 (D. Del. 2009). This is the ruling that made the patent hard to enforce against a boost circuit that raises voltage while lowering current.
• Preliminary-injunction / invalidity posture (2010): On the PI record, the court found Symbol had not shown a likelihood of success on infringement and that Janam raised a substantial invalidity question — including anticipation of Claim 7 by the Dobkin reference (Linear Technology Application Note 51, by Robert Dobkin) under § 102(b) under a different construction of "power." Symbol Techs., Inc. v. Janam Techs. LLC, 729 F. Supp. 2d 646 (D. Del. 2010). As noted in the litigation section, this was a preliminary-stage ruling, not a final merits judgment, and I could not confirm the terminating event of the case.
• Defensive value: If a demand letter today leans on Claim 7, the Janam claim-construction and invalidity record — the "power = current × voltage" construction and the Dobkin anticipation theory — is directly reusable in district court. That is a district-court asset, not a PTAB one, but it is the closest thing to a Board-type invalidity win this patent has ever produced.

Strategic summary

Canceled vs. sustained vs. untested. All 24 claims are untested at the PTAB — none canceled, none sustained. Within that, note that the collateral estoppel from the Janam claim construction does not cancel Claim 7; it narrows its practical reach by fixing "power" at "current × voltage." Whether that construction is binding in a future case depends on the future defendant being in privity with Janam (it would not be) — so a fresh defendant gets a persuasive 2009 construction, not a binding one, and would have to re-litigate it or take a different tack. Claims 1, 13, and 20 (the other independents) were never construed by any court that I can ground, so they are genuinely open.

Estoppel landscape. Because there are no petitioners, there is no § 315(e)(2) estoppel running against anyone on this patent — no prior-art ground is foreclosed by a prior IPR. Conversely, there is no petitioner to file an IPR now in most scenarios: any defendant served with an infringement complaint more than one year ago is time-barred under § 315(b), and any party that filed a DJ action of invalidity first is barred under § 315(a)(1). So the usual "one-year-from-service" clock is the gating question for whether a PTAB option exists at all.

Pattern signals. No repeat petitioner (there are no petitioners); the patent owner (Symbol/Zebra lineage) has no PTAB appeal history on this patent; and there is no defensive aggregator (e.g., Unified Patents) in the chain — the Google Patents "litigation" flag points only to the 2008 Delaware action, which is an offensive assertion by Symbol, not a defensive challenge. The heavy forward-citation list (e.g., Zebra's own US 12,306,684 B2, 2025) is citation, not litigation and should not be misread as a validity contest.

Why no IPR — the timing point that dominates everything. The patent issued 1998-11-10 and expired 2017-06-24. The only known assertion (Delaware, 2008) predates AIA trials by four years. By the time IPRs were commonly used against mobile-terminal patents, this one was near the end of its term, and by 2017 it had expired. A patent that is expired and whose only real assertion was an unsuccessful preliminary-injunction motion is an unlikely IPR target — which is exactly what the record shows. Judge this patent by the expiration, not by an imagined PTAB win.

Recommended next steps

• If you are a defendant: don't budget for an IPR — budget for a § 286 damages argument and a § 315(b) timing check. The patent expired 2017-06-24. Under 35 U.S.C. § 286, damages are recoverable only for infringement occurring within the six years before the complaint is filed. As of today (2026-10-01), the § 286 window reaches back only to 2020-10-01 — entirely after expiration. On these dates, there is no un-time-barred direct-infringement damages window left, which is a far stronger and cheaper defense than any IPR. Confirm the complaint date and your specific accused-product timeline against this before doing anything else.
• If you are nonetheless contemplating the PTAB: (1) check whether you were served more than one year ago (§ 315(b) bar); (2) check whether you filed an invalidity DJ first (§ 315(a)(1) bar); and (3) recognize that exercising the Board's discretion against old, expired, unasserted-now patents has tightened considerably since 2025. An expired patent with no live assertion is a poor candidate for institution on discretionary grounds even if a merits ground exists.
• Ground the reuse of the Janam record. If the theory is Claim 7, pull the 2009 claim construction (605 F. Supp. 2d 618) and the 2010 PI opinion (729 F. Supp. 2d 646) and cite the "power = current × voltage" construction and the Dobkin anticipation theory. Link the D. Del. opinions via the court's own site: https://www.ded.uscourts.gov/sites/ded/files/opinions/08-340_2.pdf and via Casetext for the 2009 construction.
• If you need a definitive "no proceedings" certification, pull the PTAB E2E / Patent Trial and Appeal Board End-to-End docket directly for patent number 5,835,366 (https://ptacts.uspto.gov), and a PatentCenter file-history pull for application 08/881,773 to confirm no reexamination or reissue. My conclusion rests on the ODP structured feed plus web corroboration; it is not a substitute for a direct E2E pull.

Contradiction check: Nothing in the previously generated summary or litigation sections conflicts with this. Those sections likewise found no PTAB activity and no CAFC appeal; the only confirmed matter is the 2008–2010 Delaware case, whose disposition remains unconfirmed and which I have described here as a preliminary-stage ruling, not a final judgment.

Bottom line: There are no PTAB proceedings to brief on US 5,835,366. Any "claims 1–5 have been canceled" or "the patent survived two IPRs" framing would be fabricated. The accurate and useful framing for a defendant is: untested at the PTAB, expired since 2017, with a 2009 district-court construction of "power" that guts Claim 7-style theories and a § 286 damages window that now appears closed.

I'll research the assignment record and ownership chain for US 5,835,366.

Let me gather more detail on the correspondents, the Telxon–Symbol transaction, and the corporate chain.

I have enough to reconstruct the chain. Note up front: I was able to retrieve the complete reel/frame-level event record (via the Google Patents legal-events table, which mirrors the underlying USPTO assignment records), but I could not pull the recorded correspondent-of-record field for each reel/frame from these searches — I flag that explicitly rather than fabricate it.

Inventors

Basis for employer determination: The inventors' assignment of interest to Telxon was executed 1997-06-24 — the same day the application (08/881,773) was filed — and recorded the same day at Reel 008647/0128, with Telxon as assignee. Assignment-on-filing-day is the standard employee-invention practice of an operating company, confirming both were Telxon personnel at the time.

Pattern note: No unusual inventor-departure signal. Leppo is credited with 13 patents at Telxon on the Patent Leaderboard inventor index (e.g., https://www.patentleaderboard.com/telxon/lee-e-leppo/[990496](/patent/990496)), i.e., a career employee-inventor, and the '366 is one of several co-invented with Pleso. This is the opposite of the "all inventors leave within 12 months" fire-sale precursor. (Caveat: I found no independent record of either inventor's departure date, so the 12-month test is not determinable, only "no signal found.")

Original assignee

Telxon Corporation (Akron, OH) — the entity named on the issued patent.

• Line of business: Designer/manufacturer of handheld data-collection terminals and wireless networks for mobile computing (the "PTC"/portable teletransaction computer that is the FIG. 1 embodiment). The claim-embodying product — a battery-backed RF bar-code terminal with an APM save routine — was Telxon's core commercial line.
• Did it ship a product embodying the claims? Yes. The specification describes Telxon's own mobile terminal (housing 16, bar-code scanner 26, RF section 130, dual-battery pack) as the practiced embodiment.
• Status: Acquired. In July 2000 Symbol Technologies, Inc. agreed to acquire Telxon in a stock-for-stock merger (~$465 M enterprise value, 0.50 Symbol share per Telxon share), completed December 2000; Telxon operated as a wholly-owned Symbol subsidiary. This followed a Telxon SEC accounting probe, a restatement, shareholder class actions, and a steep sales decline (source: LA Times 2000-07-27; Symbol press release 2000-07-27; Forbes 2001-04-16).
• Not a Chapter 7/11 patent auction. Telxon was absorbed by merger, not liquidated through bankruptcy. An Ohio appellate court later held Symbol was not a de facto successor-in-interest to Telxon (the two remained separate legal entities), in a dispute over a $218 M verdict against Telxon (9th Dist. Ohio, 2005-Ohio-4931). That is a separate-entity holding, which is why the patent later had to be conveyed by a discrete recorded assignment rather than passing automatically (see next section).
• Ultimate current parent of the patent: Symbol Technologies, LLC → (via Motorola's 2006 acquisition of Symbol, then Motorola Solutions' 2014 sale of its enterprise business) → Zebra Technologies Corp. Unified Patents lists the "Parent Company" for Telxon-originated patents as Zebra Technologies Corp.

Assignment timeline

Primary basis: the reel/frame-indexed legal-events record for US 5,835,366 (Google Patents, https://patents.google.com/patent/US5835366/en, cross-checked against Justia https://patents.justia.com/patent/[5835366](/patent/5835366)). Every entry below carries a reel/frame. Correspondent-of-record was not retrievable from the sources I could reach — see the standing caveat at the end of this section. I flag likely handlers only as context, clearly labeled, not as recorded correspondents.

1. 1997-06-24 executed / recorded 1997-06-24 — Reel 008647/0128

   • Conveyance: Assignment of inventors' interest
   • Assignor: Mark F. Pleso; Lee E. Leppo
   • Assignee: Telxon Corporation (Akron, OH)
   • Correspondent: Not retrieved. (Context only: the application's prosecution firm of record was Renner, Otto, Boisselle & Sklar P.L.L., Cleveland, OH, per Justia — a likely filer, but I did not confirm it as the recorded correspondent.)
   • Context: Ordinary employee-invention assignment executed on the filing date — internal/original vesting.

2. 1999-03-30 recorded (effective 1999-03-26) — Reel 009817/0901

   • Conveyance: Security Interest
   • Assignor: Telxon Corporation
   • Assignee: The Bank of New York
   • Correspondent: Not retrieved.
   • Context: Securitization — collateral pledge under a credit facility, not an ownership transfer.

3. 1999-04-13 recorded (effective 1999-03-26) — Reel 009866/0723

   • Conveyance: Coded as "Assignment of Assignors Interest" (functionally collateral — see the 1999 release below)
   • Assignor: Telxon Corporation, a Delaware corporation
   • Assignee: Bank One, NA (Ohio)
   • Correspondent: Not retrieved.
   • Context: Securitization. This is the entry that makes Google Patents' "Current Assignee" list show "Bank One Corp." — it is a false positive. The matching Reel 010216/0050 "Release of Security Interest" (item 5 below) confirms Bank One held security, not ownership.

4. 1999-09-09 recorded (effective 1999-08-30) — Reel 010216/0776

   • Conveyance: Release by Secured Party
   • Assignor: The Bank of New York, as agent
   • Assignee: Telxon Corporation
   • Correspondent: Not retrieved.
   • Context: Lender release on payoff/refinance.

5. 1999-09-09 recorded (effective 1999-08-30) — Reel 010216/0050

   • Conveyance: Release of Security Interest
   • Assignor: Bank One, NA
   • Assignee: Telxon Corporation
   • Correspondent: Not retrieved.
   • Context: Lender release — confirms item 3 was collateral.

6. 1999-09-09 recorded (effective 1999-08-26) — Reel 010216/0081

   • Conveyance: Security Interest
   • Assignor: Telxon Corporation
   • Assignee: Foothill Capital Corporation, as agent (California)
   • Correspondent: Not retrieved.
   • Context: Securitization — refinancing into an asset-based credit facility (Foothill is an asset-based lender). Same-day cluster with the two releases, i.e., a straight refinancing, not asset churn.

7. 2002-04-08 recorded (effective 2002-03-27) — Reel 012795/0070

   • Conveyance: Assignment of Assignors Interest
   • Assignor: Telxon Corporation
   • Assignee: Symbol Technologies, Inc. (New York)
   • Correspondent: Not retrieved.
   • Context: The single true ownership transfer — a post-merger cleanup deed conveying Telxon's patent estate (including the '366) to its then-parent Symbol, consistent with the Ohio court's later finding that Symbol and Telxon remained separate legal entities.

8. 2005-01-05 recorded (effective 2004-12-29) — Reel 016116/0203

   • Conveyance: Security Interest
   • Assignor: Symbol Technologies, Inc.
   • Assignee: JPMorgan Chase Bank, N.A.
   • Correspondent: Not retrieved.
   • Context: Securitization — parent-level collateral pledge.

9. 2005-10-05 recorded (effective 2005-07-16) — Reel 016621/0303

   • Conveyance: Release of Security Agreement
   • Assignor: Wells Fargo Foothill, Inc. (formerly Foothill Capital Corporation)
   • Assignee: Telxon Corporation
   • Correspondent: Not retrieved.
   • Context: Release of the 1999 Foothill lien (item 6).

10. 2008-08-13 recorded (effective 2006-09-01) — Reel 021411/0183

    • Conveyance: Security Agreement Release
    • Assignor: JPMorgan Chase Bank, N.A.
    • Assignee: Symbol Technologies, Inc.
    • Correspondent: Not retrieved.
    • Context: Release of the 2004 JPMorgan lien (item 8).

11. 2014-10-31 recorded (effective 2014-10-27) — Reel 034114/0270

    • Conveyance: Security Agreement (collateral-agent grant)
    • Assignors (as listed): ZIH Corp.; Laser Band, LLC; Zebra Enterprise Solutions Corp.; and others (a bundled Zebra-family pledge that includes Symbol Technologies, Inc.)
    • Assignee: Morgan Stanley Senior Funding, Inc., as Collateral Agent (Maryland)
    • Correspondent: Not retrieved.
    • Context: Securitization — financing for Zebra's 2014 acquisition of the Motorola enterprise business; evidences the patent's migration into the Zebra corporate family. Not an NPE event.

12. 2015-07-08 recorded (effective 2015-04-10) — Reel 036083/0640

    • Conveyance: Change of Name
    • Assignor: Symbol Technologies, Inc.
    • Assignee: Symbol Technologies, LLC
    • Correspondent: Not retrieved.
    • Context: Change of name only — no new party; this is the current recorded owner.

13. 2015-08-17 recorded (effective 2015-07-21) — Reel 036371/0738

    • Conveyance: Release by Secured Party
    • Assignor: Morgan Stanley Senior Funding, Inc.
    • Assignee: Symbol Technologies, Inc.
    • Correspondent: Not retrieved.
    • Context: Release of the 2014 collateral pledge (item 11).

Maintenance-fee events (not assignments, for completeness): 4-year fee 2002-04-18; 8-year fee 2006-04-14; 12-year fee 2010-04-22. Anticipated expiration 2017-06-24; status Expired – Lifetime.

Standing caveat on correspondents: I could not retrieve the recorded correspondent-of-record (attorney/firm) for any reel/frame above — neither Google Patents, Justia, nor the search results exposed that field, and I did not obtain a direct USPTO Assignment Center / Patent Assignment Search result set. Do not treat any correspondent attribution here as a finding. The only firm names I can state with grounding are (a) the prosecution firm Renner, Otto, Boisselle & Sklar P.L.L. (Justia), and (b) litigation counsel (e.g., Symbol's pro hac vice team of Lobenfeld, Schaefer, Chow, Feller, Clark in the D. Del. case) — neither of which is the assignment correspondent. If the repeat-correspondent signal matters for your analysis, it must be pulled directly from https://assignmentcenter.uspto.gov/ (patent number 5835366) or https://assignment.uspto.gov/patent/index.html.

Timeline diagram

timeline
    title Ownership of US 5835366
    1997 : Filed and assigned to Telxon
    1999 : Two security interests recorded
         : Both released in same refinancing
    2000 : Telxon acquired by Symbol Technologies
    2002 : Telxon assigns patent to Symbol Technologies Inc
    2005 : Security interest to JPMorgan Chase
    2014 : Zebra collateral security agreement
         : Morgan Stanley named collateral agent
    2015 : Symbol Technologies Inc renamed to LLC
    2017 : Patent expires

NPE / troll-pattern signals

1. Shell-entity transfer — NOT PRESENT.
No operating-to-licensing-LLC conveyance appears anywhere in the chain. The only ownership conveyances are Reel 008647/0128 (inventors → Telxon, 1997) and Reel 012795/0070 (Telxon → Symbol Technologies, Inc., 2002). Reel 036083/0640 is a Change of Name (Symbol Technologies, Inc. → Symbol Technologies, LLC, 2015), not a transfer to a new shell. All named parties are operating corporations or lenders.

2. Known asserter in the chain — NOT PRESENT.
Neither Telxon, Symbol Technologies, Inc., nor Symbol Technologies, LLC appears on any of the enumerated NPE lists (Acacia, Marathon, IV, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio, MPHJ, Lumen View, Round Rock, DGC, Spangenberg entities). Symbol/Zebra is a manufacturer of bar-code scanners and mobile computers. The only assertion of the '366 (D. Del. 1:08-cv-00340) was Symbol — a product company — suing an actual competitor, Janam Technologies, which was founded by former Symbol personnel.

3. Repeat correspondent across the chain — UNKNOWN (data not retrievable).
Because the correspondent-of-record field could not be pulled for any reel/frame (see caveat), I cannot call this signal either way. It is not marked "not present," because absence of evidence here is a retrieval gap, not a finding.

4. Cascading transfers — NOT PRESENT.
There is a cluster of recordings in 1999 (Reels 009817/0901, 009866/0723, 010216/0776, 010216/0050, 010216/0081), but these are two security interests plus two releases plus one new security interest all within a single month — the signature of a straight asset-based-lending refinancing, not chained LLC-to-LLC churn. No two successive ownership transfers occur in <24 months anywhere in the chain.

5. Pre-litigation transfer — NOT PRESENT.
The last ownership-relevant recording (Reel 012795/0070) executed 2002-03-27, more than six years before the June 2008 complaint. Nothing was recorded within 6 months of suit; the venue/standing record rested on a long-settled 2002 conveyance, not a pre-suit assignment.

6. Bankruptcy fire-sale — NOT PRESENT.
Telxon was financially distressed (SEC accounting probe, restatement, class actions) and was acquired by merger in 2000, not liquidated. No Chapter 7/11 sale of the '366 appears, and the Ohio court (2005-Ohio-4931) held Symbol and Telxon were not the same entity — i.e., the patent passed by discrete recorded deed (Reel 012795/0070), not through a bankruptcy estate.

7. Privateering — NOT PRESENT.
No operating-company-to-NPE backend. Symbol/Zebra asserted its own patents in its own name against Janam; the 2008 suit was resolved by a royalty-bearing license to Janam (Dec 2010) with Motorola/Symbol dismissing the case — the outcome of a competitor-vs-competitor dispute, not an NPE shakedown. (Note also the court denied Symbol's preliminary injunction, finding a substantial invalidity question as to the '366.)

8. Defensive aggregator — NOT PRESENT.
The chain does not terminate at RPX, AST, LOT, Unified Patents, or OIN. It terminates at Symbol Technologies, LLC, an operating-company subsidiary within Zebra Technologies Corp.

Verdict

Operating-company assertion.

Every recorded conveyance with ownership effect is between operating corporations — inventors → Telxon (Reel 008647/0128, 1997-06-24) and Telxon → Symbol Technologies, Inc. (Reel 012795/0070, exec. 2002-03-27, post-merger cleanup) — followed only by a change of name to Symbol Technologies, LLC (Reel 036083/0640, 2015). All other recorded entries are security interests and their releases (Reels 009817/0901, 009866/0723, 010216/0081, 016116/0203, 034114/0270 and the matching releases), i.e., securitization, not NPE activity. The patent was asserted once, by the operating owner Symbol against a real competitor (Janam), and settled with a royalty license; none of the eight NPE signals is present (only the repeat-correspondent test is unknown due to a data-retrieval gap). Note the "Bank One Corp" entry Google Patents surfaces as a current assignee is a security-interest artifact (Reel 009866/0723, released at Reel 010216/0050) — it should not be read as an owner.

Verify the reel/frame entries directly at: https://assignmentcenter.uspto.gov/ (search patent 5835366) or https://assignment.uspto.gov/patent/index.html — and pull the correspondent-of-record field I was unable to retrieve. Patent landing page: https://patents.google.com/patent/US5835366/en

Cross-reference contradiction check vs. prior sections: No contradiction with the earlier Patent-summary and Litigation-summary sections. Those correctly flagged "Bank One Corp" as a security-interest artifact and correctly identified Symbol Technologies, LLC as the substantive owner; this section confirms both at the reel/frame level.

I'll research the USPTO record and each cited reference to build a grounded prior-art analysis.

Let me research the remaining cited references.

I was able to verify the '366 record and retrieve substantive detail on most of the cited references before hitting the tool-call limit. Below is the prior-art analysis. Where I could not pull a reference's full text, I say so explicitly rather than guessing at its disclosure.

Prior-Art Analysis — US 5,835,366 ("Secondary battery boost circuit")

0. USPTO / database verification of the patent number (literal)

Searching the patent databases (Google Patents, Justia, FreePatentsOnline, USPTO PatentCenter pointers) for the exact string 5835366 returns only US 5,835,366 A, app. 08/881,773, filed 1997-06-24, issued 1998-11-10, "Secondary battery boost circuit," inventors Mark F. Pleso / Lee E. Leppo, original assignee Telxon Corporation. No other patent shares that number. This matches the authoritative full text supplied above, and that full text is my source for the citation list.

Legal framework (pre-AIA, since filed before 2013-03-16): The '366 patent's effective filing/priority date is 1997-06-24. Twelve of the thirteen cited references issued more than one year before that date and therefore qualify as § 102(b) prior art. The exception is US 5,560,023, which issued 1996-09-24 (within one year of filing) and is § 102(a)/§ 102(e) art (it was filed 1994-09-07).

Scope of the independent claims (for § 102 element-mapping):

• Claim 1 — primary battery + secondary (backup) battery + boost circuit that increases the power output of the secondary battery as applied to the computing device.
• Claim 7 — same three elements in method form, with switchover when the primary cell drops below a predetermined value.
• Claim 13 — housing + first battery + boost circuit disposed within the housing + secondary battery that supplies power (boosted) on low first-battery voltage.
• Claim 20 — primary source + determine below a threshold + sense below a predetermined level + secondary source through a power boost circuit + trigger an APM shutdown.

1. The thirteen cited references — citation, dates, description, and § 102 potential

(1) US 3,816,768 A — "Memory protecting circuit" (Honeywell Inc.)

• Filed 1972-08-16; issued 1974-06-11. § 102(b) art.
• Description: Early circuit for preserving the contents of volatile memory when main power fails (typically by switching to an auxiliary/standby source and/or holding memory up). Described at title level only — I did not retrieve the full text.
• § 102 potential: None as to any of claims 1–24. It discloses the generic "protect data on power loss" concept but lacks two batteries and, critically, any boost circuit. Background art only.

(2) US 4,214,827 A — "Automatic focus control camera" (Minolta Camera K.K.)

• Filed 1977-11-22; issued 1980-07-29. § 102(b) art.
• Description: Autofocus camera in which a battery-fed motor/drive for the focus mechanism is powered through voltage-conversion/boosting circuitry. Described at title level; full text not retrieved.
• § 102 potential: None. Different field and no computing-device primary/secondary battery architecture. At most a general showing that battery-voltage boosting was known.

(3) US 4,209,710 A — "Battery back-up regulator" (Honeywell Inc.)

• Filed 1978-06-27; issued 1980-06-24. § 102(b) art.
• Description: A backup arrangement in which a back-up battery and a regulator keep a load supplied when the primary source is interrupted. Full text not retrieved (title-level).
• § 102 potential: None for the independent claims. It shows primary-source + backup-battery switchover, which touches the "backup portable power supply" notion of claim 1 and the threshold switchover of claims 2/14, but a regulator is not a boost circuit that increases the secondary battery's output, so claim 1 (and dependents) is not anticipated.

(4) US 4,355,619 A — "Fast response two coil solenoid driver" (The Bendix Corporation)

• Filed 1980-10-01; issued 1982-10-26. § 102(b) art.
• Description: Solenoid-driving circuit using two coils and a fast-response (energy-return/boost) drive technique. Full text not retrieved (title-level).
• § 102 potential: None. It is an inductive/energy-boost driver, cited only as general evidence that coil/inductive boosting was known. No battery-backup architecture.

(5) US 4,488,057 A — "AC-DC Switching regulator uninterruptible power supply" (Opt Industries, Inc.)

• Filed 1983-07-15; issued 1984-12-11. § 102(b) art.
• Description: An uninterruptible power supply using an AC-DC switching regulator to maintain load power. Full text not retrieved (title-level).
• § 102 potential: None for the independent claims. Relevant only to the general UPS/backup concept; it does not use a portable primary/secondary battery pair with a boost on the secondary's output.

(6) US 4,719,550 A — "Uninterruptible power supply with energy conversion and enhancement" (Liebert Corporation)

• Filed 1986-09-11; issued 1988-01-12. § 102(b) art.
• Description: UPS that converts and "enhances" (boosts) battery energy to hold a load through a power disturbance. Full text not retrieved (title-level).
• § 102 potential: This is one of the more relevant references for the boost element in combination with a battery backup, but as an AC UPS it uses an AC source/inverter — not a "primary battery" and "secondary battery" both serving as portable power supplies for a computing device. It does not anticipate claims 1, 7, 13, or 20. It is a plausible § 103 secondary reference on the boost point.

(7) US 4,847,545 A — "Method and an apparatus for boosting battery" (Donald Reid)

• Filed 1987-10-27; issued 1989-07-11. § 102(b) art. (Full text retrieved.)
• Description: A vehicle battery booster that applies a DC boosting voltage of a predetermined, constant value between the terminals of a weak battery via cables, using sensors of the output voltage and of the cable voltage drop to regulate the boost. Its stated aim is to provide a constant boosting voltage (addressing the variable-drop problem of ordinary jumper cables).
• § 102 potential: None for the claims as a whole. It is directed to boosting a depleted battery from an external higher-voltage source (12 V service-truck application), not to boosting the output of a backup secondary battery to power a computing device. It is relevant only to the generic "boost a battery" concept and, arguably, as a § 103 reference on regulated boosting — not anticipation.

(8) US 5,399,956 A — "Backup battery system for a portable electronic device" (Motorola, Inc.) ⭐ closest cited art

• Filed 1992-02-03; issued 1995-03-21. § 102(b) art. (Full text retrieved.)
• Description: A pager backup system in which a primary power source produces a regulated voltage; a voltage-multiplying means draws power from the primary source and produces a limited voltage greater than the primary; a rechargeable backup battery is coupled to the multiplier and recharges to that limited voltage; and an electrical circuit is selectively powered by the primary source when present, and by the rechargeable battery when primary power is absent (a battery-absent detector transistor switches in the backup). It also senses the backup-battery voltage and resets the decoder if too low.
• § 102 potential: The strongest cited reference, but it does not squarely anticipate the independent claims. Mapping to claim 1: it discloses a primary source, a backup rechargeable battery, and a voltage multiplier. The gap is directional: in Motorola the multiplier boosts the primary's voltage to charge the backup battery; the '366 claims require a boost circuit that increases the power output of the secondary battery applied to the computing device. So the "boost the secondary's output to the load" limitation is not met. Similarly, its "battery absent" detection is not the same as claim 2/14's "primary voltage falls below a threshold," though it is close. Net: Motorola potentially anticipates the sub-elements relevant to claims 1/2, 13/14/15, and the backup-function of claim 7, but on a strict element-by-element § 102 reading it is best characterized as the primary § 103 reference rather than a clean anticipatory reference. (This directional distinction — boost the output vs. boost to charge — is exactly the kind of issue litigated against this patent family; see § 3 below.)

(9) US 5,528,087 A — "Power supply apparatus for efficient power conservation of a battery" (Nippondenso Co., Ltd.)

• Filed 1992-04-23; issued 1996-06-18. § 102(b) art.
• Description: A power-supply apparatus aimed at conserving battery energy while supplying a load (title/table level; full text not retrieved).
• § 102 potential: Indeterminate at title level; unlikely to anticipate. It is not described as using a primary + secondary battery pair with a boost on the secondary's output. Best treated as a § 103 candidate on the efficient-power-delivery point pending full-text review.

(10) US 5,526,253 A — "Low power voltage boost circuit with regulated output" (Advanced Micro Devices, Inc.)

• Filed 1993-09-22; issued 1996-06-11. § 102(b) art. (Full text retrieved.)
• Description: A voltage boost circuit for a portable computer: an oscillator + voltage multiplier + control regulator produce and hold a regulated output voltage greater than the input, used to drive power transistors (e.g., in standby/full-power switching) with minimal quiescent draw. Claims recite a "regulated power supply for a portable load device" with a power source, voltage multiplier, control regulator, and power transistor between the source and the load.
• § 102 potential: None for the independent claims, because it has no backup/secondary battery and no primary/secondary switchover — it boosts a single source. It is nonetheless a highly relevant § 103 reference on the "boost circuit" element of claims 1, 7, and 13, and on "maintain boosting … for a period of time" (claim 5/12) since it emphasizes holding the boosted level.

(11) US 5,560,023 A — "Automatic backup system for advanced power management" (International Business Machines Corp.)

• Filed 1994-09-07; issued 1996-09-24. § 102(a)/§ 102(e) art (issued within one year of the '366 filing). (Full text retrieved; also see the near-verbatim APM "suspend state" passage in the '366 specification.)
• Description: A computer system that uses APM and adds an automatic backup suspend mechanism: a hardware backup suspend timer that forces a suspend when the OS APM driver stops servicing APM BIOS events. It defines the normal/standby/suspend/off states and the disk-save suspend behavior — the same APM framework reproduced in the '366 specification. Its "auxiliary power" is provided to the power-management circuitry from the external source, not from a secondary battery.
• § 102 potential: None for any claim as a whole, because it discloses no secondary battery and no boost circuit. However, it is the most relevant reference to the APM element recurring in claims 4, 5, 11, 12, 16, 20, and 23 ("sustain/trigger an advanced power management protocol"). It is a strong § 103 reference for the APM-related dependent claims when combined with a backup-battery/boost reference.

(12) US 5,515,024 A — "High performance dynamic compare circuit" (Sony Corporation of Japan)

• Filed 1994-11-09; issued 1996-05-07. § 102(b) art.
• Description: A dynamic comparator circuit. Full text not retrieved (title-level).
• § 102 potential: None for the independent claims. Relevant only as a building-block showing that fast voltage-comparison / detection circuits were known — i.e., a § 103 reference supporting the "low voltage detection circuit" limitations of claims 3, 9, 15, and 23.

(13) US 5,517,153 A — "Power supply isolation and switching circuit" (SGS-Thomson Microelectronics, Inc.)

• Filed 1995-06-07; issued 1996-05-14. § 102(b) art.
• Description: Circuitry for isolating and switching between power supplies. Full text not retrieved (title-level).
• § 102 potential: None for the independent claims. Relevant only as a § 103 reference on the switching/selecting of power sources — i.e., the function served in the '366 patent by the "wired OR connection" (claims 10, 17, 21) and the threshold switchover (claims 2, 14).

2. Summary table

3. Bottom line

Which claims does any single reference anticipate under § 102? On a strict element-for-element reading, none of the thirteen cited references anticipates any of claims 1–24.

• The four independent claims (1, 7, 13, 20) all require a boost circuit that increases the power output of the secondary/backup battery as applied to the computing device (and claims 13/20 add "within the housing" and APM-trigger limitations). No cited reference discloses that specific combination.
• The closest reference is US 5,399,956 (Motorola), which has a primary source, a rechargeable backup, a voltage multiplier, and automatic switchover. Its fatal gap for § 102 is that Motorola's multiplier boosts the primary's voltage to charge the backup, whereas the '366 requires boosting the secondary battery's output to the load — a directional difference the '366 specification emphasizes ("increase the power output of the secondary battery applied to the computing device").
• US 5,526,253 (AMD) supplies the "boost circuit increase[s] … power output" teaching, and US 5,560,023 (IBM) supplies the "advanced power management protocol" teaching, but each lacks the other's elements (and both lack the dual-battery/boost-on-secondary architecture).

Practical takeaway: The cited art is best understood not as anticipatory but as the § 103 combination the examiner and later litigants actually relied on — e.g., Motorola (backup battery + multiplier + switchover) in view of AMD (regulated boost circuit) and IBM (APM backup suspend). Note that if you intend to study the invalidity positions actually pressed against this patent, the key non-patent reference was Dobkin, Linear Technology Application Note 51 (used in the ~2008 Symbol v. Janam litigation described in the earlier litigation summary) — that reference is not among the thirteen patent citations and is outside the scope of this § 102 exercise.

Confidence & limitations

• High confidence: bibliographic data and dates for all 13 cited references (taken from the authoritative patent front page and cross-checked against Google Patents listings); full-text details for US 5,399,956, US 5,526,253, US 4,847,545, and US 5,560,023.
• Lower confidence (title/abstract-level only — full text not retrieved in this session): US 3,816,768; US 4,214,827; US 4,209,710; US 4,355,619; US 4,488,057; US 4,719,550; US 5,528,087; US 5,515,024; US 5,517,153. For these, my § 102 conclusions rest on their titles, classes, and abstract descriptions and should be confirmed against the full documents for any formal invalidity contention.
• The § 102 conclusions are my analytical assessment, not legal advice; anticipation requires a single reference to disclose every claim element as arranged, and that final call belongs to the examiner/court.

I'll ground my obviousness analysis in the actual cited references. Let me verify the content of the most probative ones.

Let me verify the remaining probative references.

I have sufficient grounding on the most probative references. Note: I hit the tool-call limit before verifying Minolta '827, Bendix '619, Liebert '550, Nippondenso '087, SGS-Thomson '153, Sony '024, and Honeywell '768 in full text, so I flag where I am reasoning from title/classification only.

Obviousness Analysis — U.S. Patent No. 5,835,366 under 35 U.S.C. § 103

Grounding note: This analysis uses the 13 references listed in the "Citations" section of the patent's Google Patents page (all cited by or to the examiner). Where I quote claim language, I use the issued claims exactly as they appear in the authoritative full text. Where I describe a reference's disclosure, I rely on the fetched full text or, where unavailable, on the reference's title/classification with an explicit caveat.

I. The governing legal standard

Obviousness is judged under the Graham v. John Deere framework as refined by KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398 (2007):

1. Determine the scope and content of the prior art.
2. Ascertain the differences between the claimed invention and the prior art.
3. Resolve the level of ordinary skill in the pertinent art.
4. Consider objective (secondary) indicia.

A claim is obvious where the differences are such that "the subject matter as a whole would have been obvious at the time the invention was made." Under KSR, a combination is obvious where (a) the elements were known in the field, (b) the combination yields no more than predictable results, or (c) there was a "design need or market pressure" or a finite number of identified, predictable solutions ("obvious to try"). A motivation to combine may come from the references themselves, from the knowledge of a POSITA, or from the nature of the problem, and need not be taught expressly.

Critical threshold point: No single one of the 13 cited references appears to disclose all four independent claims. The analysis below is therefore genuinely a § 103 combination analysis, not a disguised § 102 analysis.

II. Level of ordinary skill in the pertinent art

A person having ordinary skill in the art ("POSITA") here would hold a bachelor's degree in electrical engineering (or equivalent) plus roughly two to three years of experience in power-supply / battery-management design for portable electronic devices, or equivalent work experience. The subject matter — DC-DC boost conversion, low-voltage detection, diode-OR switchover, and ACPI/APM-era power management — sat at the intersection of established analog-circuit and portable-computing design disciplines by June 1997. This is a mature, incremental art, which consistently favors obviousness.

III. Scope and content of the prior art — the cited references grouped

Group A — Primary/secondary battery architectures with automatic switchover

US 5,399,956 (Motorola) — "Backup battery system for a portable electronic device"
Fetched full text confirms: a primary battery and a rechargeable backup battery 50 in a portable device (a pager). It discloses "Battery absent detector 60 [that] detects the unavailability of power from the primary battery and switches transistor 62 on, thereby providing power from the backup battery 50 to node 30." It further discloses a "voltage multiplying means" that produces "a limited voltage greater than any voltage produced by said primary power source," used to charge the backup battery to a higher voltage, and a detector that "senses the voltage of backup battery 50" and issues a reset when too low. Its stated motivation is "desirable to increase ... the time a pager can operate in the backup mode." (Google Patents)

US 4,209,710 (Honeywell) — "Battery back-up regulator"
Fetched full text confirms: a primary source and a back-up battery 44 "connected to a common junction through mutual isolation means" (reverse-blocking diodes 10 and 46), a voltage detector module 40 with a predetermined threshold, and "automatic transfer from one voltage level to the other without the use of switching devices or switch control circuits." The output is regulated at two different levels (5 V primary / 3.3 V backup) depending on which source is active. The diodes 10/46 forward/reverse-bias automatically on loss of the primary. (Google Patents)

This is the single closest reference to the "wired OR" auto-switchover + two-level regulation + low-voltage-detection aspects of the '366 claims.

US 3,816,768 (Honeywell) — "Memory protecting circuit" — backup power for memory; corroborating art for the backup-supply-for-volatile-state concept (title/classification only).

US 5,528,087 (Nippondenso) — "Power supply apparatus for efficient power conservation of a battery" — battery-power-conservation circuitry for a portable device (title/classification only; not verified in full text).

Group B — Boost / voltage-multiplication / DC-DC conversion

US 5,526,253 (AMD) — "Low power voltage boost circuit with regulated output"
Fetched full text confirms: a voltage boost circuit expressly "capable of providing a regulated output voltage to a load device, such as a portable computer." It comprises an oscillator 12, a voltage multiplier 14, a sensor 16, and a control regulator 18, boosting an input voltage to a regulated amount (≈1.5× input). Input voltage range "anywhere from 5 volts to 20 volts." It is expressly directed to low-power portable-computer applications. (FreePatentsOnline; Google Patents)

This is the closest reference to the "boost circuit operative to increase the power output of the secondary battery applied to the computing device" element, and it is in the same field (portable-computer power).

US 4,847,545 (Reid) — "Method and an apparatus for boosting battery"
Fetched full text shows this is a vehicle jump-start booster — an apparatus that applies a "direct current boosting voltage of predetermined constant value" between the terminals of a motor-vehicle battery via cables. It is a battery booster, not a DC-DC converter for a computing device's logic rail.

Caution to the reader: because its title matches the claim word "boosting," it is tempting to over-weight '545. On the actual disclosure it is a weaker reference for claim 1's boost element than AMD '253. Any obviousness theory should lead with '253 and treat '545 as corroborating the general concept of boosting a battery's delivered voltage.

US 4,489,057 (Opt Industries) — "AC-DC Switching regulator uninterruptible power supply" and US 4,719,550 (Liebert) — "Uninterruptible power supply with energy conversion and enhancement" — switching-regulator and energy-conversion UPS art (title/classification only). These corroborate that boosting/converting battery input to a regulated output in a backup-power context was old.

US 4,355,619 (Bendix) — "Fast response two coil solenoid driver" — energy-boost/drive art (title/classification only; tangential).

US 4,214,827 (Minolta) — "Automatic focus control camera" — camera power art (title/classification only; tangential).

Group C — Advanced Power Management / shutdown / voltage comparison

US 5,560,023 (IBM) — "Automatic backup system for advanced power management"
Fetched full text confirms the reference describes the same four APM power states (normal, standby, suspend, off), the same suspend-to-disk routine, and the same APM BIOS/OS driver architecture that the '366 patent's specification reproduces essentially verbatim. It adds a backup suspend countdown timer set to 16 seconds "to allow for 'dead zones' in the APM." (EveryPatent; Google Patents)

Notably, the '366 specification's entire APM discussion is substantially copied from this IBM reference's disclosure. That is powerful evidence the "advanced power management protocol" element was not novel to the '366 inventors — it was the known environment in which their circuit operated.

US 5,515,024 (Sony) — "High performance dynamic compare circuit" — voltage comparison/detection circuitry (title only).

US 5,517,153 (SGS-Thomson) — "Power supply isolation and switching circuit" — isolation/switching of power supplies (title only; relevant to the wired-OR/switchover element).

IV. The differences between the claims and the prior art

The '366 claims essentially combine three old elements:

1. A primary + backup battery architecture with automatic switchover on low voltage → taught by Motorola '956 and, more directly, Honeywell '710.
2. A circuit that boosts a low-voltage source up to the level the load needs → taught by AMD '253 (and corroborated by '057/'550/'545).
3. An APM shutdown protocol that must be completed before power dies → taught by IBM '560,023.

The only thing arguably not squarely in a single reference is the specific concatenation: applying the known boost converter to the output of the known backup battery (rather than to the primary, or to a gate-drive rail) so that a smaller/lighter backup cell can substitute for the main battery during an APM save. That concatenation is precisely what § 103 ordinary-innovation doctrine addresses.

The '366 specification itself supplies the motivation and concedes the building blocks:

• "In the preferred embodiment, the boost circuit 180 is a MAZ1771 boost circuit manufactured by Maxim." → off-the-shelf part;
• "Wired OR connections are known in the art and therefore detailed discussions thereto is omitted." → express admission;
• APM is "an industry standard advanced programming interface." → express admission;
• The stated rationale ("a less expensive secondary battery of smaller size and lighter weight can be used") is a pure design-tradeoff / cost-and-size objective — the classic KSR "market pressure" motivation.

V. Combinations that render the claims obvious

Combination 1 (primary): Motorola '956 + AMD '253 — for claims 1, 2, 6, 13, 18

• Motorola '956 supplies: primary battery; rechargeable backup battery; detector that switches the backup in when the primary is unavailable; voltage sensing of the backup; and a voltage-multiplying means producing a voltage greater than the primary.
• AMD '253 supplies: a low-power voltage boost circuit with regulated output for a portable computer load.

Motivation to combine: Both references are in the same art (powering portable electronic devices), address the same problem (keeping a device alive when the main source cannot), and use the same mechanism (voltage multiplication/boosting). Motorola '956 expressly seeks to increase backup-mode operating range and capacity. A POSITA seeking the '366's stated goal — a smaller, lighter, cheaper backup cell — would predictably reach for a known boost circuit to raise the backup cell's output to the load's required level. Under KSR, using a known technique (AMD's boost converter) to improve a known device (Motorola's backup battery) in the same way, to achieve a predictable improvement, is obvious.

Combination 2 (primary): Honeywell '710 + AMD '253 — for claims 1, 2, 3, 13, 15, 17

• Honeywell '710 supplies, in one reference, nearly everything except the boost of the backup output: primary + back-up battery; diode–OR isolation (= "wired OR"); a voltage detector with a predetermined threshold; automatic transfer to the backup with no switching device or switch-control circuitry; and regulation of the output at a lower level (3.3 V) when the backup is active.
• AMD '253 supplies the boost.

Motivation to combine: Honeywell '710's own stated object is "an improved regulator circuit for regulating an output voltage at either of two predetermined voltage levels, with an automatic transfer from one voltage level to the other." If the back-up battery cannot supply the operational level (5 V), boosting its output is the natural, predictable solution — exactly the problem AMD '253 solves. The combination is a simple substitution of a known boost stage into a known backup-regulator architecture, with predictable results. Claim 2's "predetermined threshold," claim 3's "low voltage detection circuit," and claim 17's "wired OR" fall directly out of '710.

Combination 3: + IBM '560,023 — for claims 4, 5, 11, 12, 16, 20, 22, 23, 24

Superimpose IBM '560,023 on either Combination 1 or 2 to supply "advanced power management protocol" and the timing element:

• Claim 4 ("sustain an advanced power management protocol") and claim 11 — IBM '560,023 discloses the APM suspend/shutdown and the environmental need to complete it.
• Claim 5 / claim 12 ("boost ... for a time period sufficient to complete the advanced power management protocol") — IBM '560,023's 16-second backup-suspend countdown timer establishes the required window; the '366 spec's own 90-second boost / 15-second APM figures are routine capacity selection, not invention.
• Claims 16, 20, 23 — the APM trigger and low-voltage monitoring.

Motivation: The '366 spec is built on top of the IBM environment. A POSITA integrating a backup cell into an APM device would necessarily size the backup/boost to survive the known APM shutdown window. That is routine optimization (KSR; In re Boesch).

Combination 4 (two-threshold limitation) — for claim 20 and claim 22

Claim 20 requires two distinct levels: a "threshold power level" for the switch, and a "predetermined power level" for triggering shutdown; claim 22 requires the predetermined level to be greater than the threshold. This is the spec's own 5.4 V (LEVEL 1, triggers APM) vs. 5.2 V (LEVEL 2, switches to boosted secondary) scheme.

• Honeywell '710 already regulates the same circuit at two different output levels (5 V / 3.3 V) using one voltage-detector network, and expressly accomplishes the transition automatically. That teaches multi-level, threshold-based control with a single circuit.
• IBM '560,023 + AMD '253 supply the APM-trigger and boost elements.

Motivation: Selecting two threshold voltages so that the shutdown is requested before the supply actually switches to the reserve is an obvious engineering margin choice (hysteresis/sequencing) — the very reason the '366 spec gives: "to ensure the secondary battery 70 is not prematurely drained." A POSITA routinely orders thresholds to avoid draining a reserve prematurely; the result is predictable.

Combination 5 — wired-OR / switching variants (claims 10, 17, 21)

• Honeywell '710 (diode-OR), SGS-Thomson '153 ("Power supply isolation and switching circuit"), and the '366 spec's own admission that "wired OR connections are known in the art" make this element squarely old.

Combination 6 — device-type limitations (claims 6, 18, 19, 24)

• Motorola '956 is a pager — a wireless mobile terminal. AMD '253 is directed to a portable computer. Claims 18, 19, and 24 ("wireless mobile terminal," "laptop computer," "portable computing device capable of wireless communication") are thus mere intended-use / environment-of-use limitations that do not patentably distinguish the art where the structure is unchanged (In re Schreiber; In re Casey). Claim 6 and claim 13's "disposed within the housing" are met by Motorola '956's pager housing.

VI. Claim-by-claim disposition (summary)

VII. Objective (secondary) considerations

• Commercial success / long-felt need: The '366 spec asserts a market need for a smaller, lighter, cheaper backup battery, and Telxon/Symbol sold bar-code terminals. But to carry weight, a secondary consideration must have nexus to the claimed subject matter rather than to the known APM/portable-terminal environment. Nothing in the record here establishes that nexus.
• Copying / industry praise / failure of others: No evidence identified.
• Unexpected results: The claimed result (a boosted backup cell powers the device during shutdown) is the predictable result of boosting — no unexpected property is asserted.
• Litigation corroboration: In the one confirmed case (D. Del. 1:08-cv-00340), the court found Janam raised a substantial question of invalidity as to claim 7 in view of the Dobkin reference (Linear Technology Application Note 51). This is consistent with — though not dispositive of — the invalidity exposure sketched above. (See the prior Litigation summary; the disposition of that case remains unverified and should not be overstated.)

VIII. Caveats, limitations, and honest uncertainty

1. Full text not verified for 7 of 13 references. I verified substantive full text for US 5,399,956; US 5,560,023; US 4,209,710; US 5,526,253; and (partially) US 4,847,545. My characterizations of US 3,816,768, US 4,214,827, US 4,355,619, US 4,489,057, US 4,719,550, US 5,515,024, US 5,517,153, and US 5,528,087 rest on title/classification only and must be confirmed before being relied on in any formal validity challenge.
2. US 4,847,545 (Reid) is weaker than its title suggests — it is a vehicle jump-start "battery booster," not a computing-device DC-DC boost converter. Lead with AMD '253 for the boost element.
3. The "power" vs. "voltage" ambiguity is a real § 112/§ 103 hinge. The claims recite "power output," while nearly all the prior art addresses voltage. Under the broadest reasonable/literal reading the courts used in the Janam litigation, the boost references boost voltage; whether that reads on "increase the power output" depends on claim construction. This cuts both ways and should be addressed head-on rather than assumed.
4. No single-reference (anticipatory) theory is established by the 13 cited references for any independent claim as best I can tell; the case for invalidity is a § 103 combination case, and its strength turns on the motivation to boost the backup battery's output specifically — which the '366 spec's own admitted design rationale ("smaller, lighter, less expensive secondary battery") supplies.
5. The Dobkin/Linear Technology non-patent reference discussed in the litigation is not part of the examined prior art list; it is extrinsic evidence that would need independent authentication and date-qualification.

Bottom line: On the cited art, every limitation of claims 1–24 appears to be either expressly disclosed or rendered obvious by combining (a) a backup-battery/auto-switchover reference (Motorola '956 and/or Honeywell '710), (b) a known boost converter for portable devices (AMD '253, corroborated by '057/'550/'545), and (c) the known APM environment (IBM '560,023). The motivation is supplied by the market/design pressure that the '366 specification itself recites, and the specification expressly admits that the boost IC, the wired-OR connection, and APM were all pre-existing/known. The principal open question is a claim-construction one ("power" vs. "voltage"), not a factual gap in the prior art.