DCT
8:15-cv-01404
Power Probe Inc v. Daniel Barber Sullivan
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: POWER PROBE, INC. (California)
- Defendant: DANIEL BARBER SULLIVAN (North Carolina)
- Plaintiff’s Counsel: RUTAN & TUCKER, LLP
- Case Identification: 8:15-cv-01404, C.D. Cal., 03/14/2016
- Venue Allegations: Plaintiff alleges venue is proper in the Central District of California because Defendant consented to jurisdiction, conducted substantial business in the district, and attempted to enforce the patent-in-suit against the Plaintiff, whose principal place of business is in the district.
- Core Dispute: Plaintiff seeks a declaratory judgment that its "Power Probe IV" and "The Hook" automotive diagnostic tools do not infringe Defendant’s patent, which relates to methods and devices for testing electrical circuits.
- Technical Context: The technology involves handheld electronic tools used by automotive technicians to diagnose electrical faults, such as high-resistance connections caused by corrosion, which can be difficult to detect with standard voltmeters.
- Key Procedural History: The complaint details the prosecution history of the patent-in-suit, noting that claims were repeatedly rejected over prior art. To secure allowance, the applicant amended the claims to include the limitation that a "test load" must be used for "replacing a component of the circuit under load" and argued this distinguished the invention from prior art that merely added a load in parallel. The complaint also notes that the Defendant previously filed a separate infringement action against Snap-on Incorporated (a reseller of Plaintiff's products) in the Middle District of North Carolina, which was stayed.
Case Timeline
| Date | Event |
|---|---|
| 1999-07-23 | '853 Patent Priority Date |
| 1999-12-27 | '853 Patent Application Filing Date |
| 2002-03-12 | '853 Patent Issue Date |
| 2014-Late | Defendant begins publicly asserting infringement |
| 2015-08-21 | Defendant files suit against Snap-on in M.D.N.C. |
| 2016-03-14 | First Amended Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,356,853 - "Enhancing Voltmeter Functionality," issued March 12, 2002
The Invention Explained
- Problem Addressed: The patent addresses the difficulty of detecting certain electrical circuit failures, particularly "high resistance faults caused by corrosion," using conventional test equipment (’853 Patent, col. 1:20-22). Such faults may only become apparent when the circuit is active and under a load, but performing such "dynamic circuit tests" can be impractical or impossible, especially if a component must be removed to access test points (’853 Patent, col. 1:47-54).
- The Patented Solution: The invention is an enhanced voltmeter apparatus and method that incorporates a "test load" and a switch (’853 Patent, Abstract). The key concept is that a technician can remove a component (like a light bulb or relay) from the circuit being tested and connect the voltmeter in its place. By closing a switch on the device, the internal "test load" is coupled into the circuit, "replacing" the removed component and allowing a technician to perform a dynamic test on the circuit wiring under a simulated load (’853 Patent, col. 2:6-14; col. 4:16-25). Comparing voltage readings with the switch open versus closed helps diagnose faults.
- Technical Importance: This approach claims to provide a conclusive and simple method for dynamic testing by enabling a technician to use a single tool to test a circuit under load at the precise point where a component was removed, which was not easily achievable with prior methods (’853 Patent, col. 2:25-31).
Key Claims at a Glance
- The complaint seeks a declaratory judgment of non-infringement of all claims, with a focus on independent claims 1, 8, 11, 13, 22, and 44 (Compl. ¶44, 98-101, 107-110).
- Independent Claim 1 (Apparatus):
- Circuitry for dynamic testing of a circuit under load, comprising:
- a test load adapted to be coupled between inputs of a digital voltmeter, the test load replacing a component of the circuit under load; and
- a switch adapted to short circuit test leads of the voltmeter through the test load.
- Independent Claim 8 (Method):
- A method for dynamic testing of a circuit under load, the method comprising:
- removing a component from the circuit under load;
- coupling leads of a digital voltmeter to remaining terminals of the removed component in the circuit;
- closing a switch to short circuit inputs of the digital voltmeter through a test load; and
- making dynamic tests of the circuit under load using the digital voltmeter, the test load completing the circuit under load.
- The complaint argues non-infringement of all claims of the '853 Patent (Compl. ¶97, 106).
III. The Accused Instrumentality
- Product Identification: The "Power Probe IV" and "The Hook" digital voltmeter products (Compl. ¶48, 58).
- Functionality and Market Context:
- The complaint alleges that both the Power Probe IV and The Hook are designed to perform dynamic testing on complete circuits with all of their original components remaining in place (Compl. ¶51, 61).
- The user manuals for the products allegedly instruct technicians to "power up components" to "verify a components correct operation" and test a "complete circuit, with all components in place" (Compl. ¶52, 62). The complaint asserts this method is fundamentally different from the patented invention, which requires removing a component (Compl. ¶53, 63).
- The complaint alleges the accused products compete with products licensed by the Defendant, such as the "181 LOADpro Dynamic Test Lead," which is marketed on platforms like Amazon.com (Compl. ¶57, 67). Exhibit M contains a screenshot from Amazon.com showing the "181 LOADpro Dynamic Test Lead" for sale, which Plaintiff alleges is a competing product licensed by Defendant (Compl. ¶57, Ex. M).
IV. Analysis of Infringement Allegations
This is a declaratory judgment action where the Plaintiff, Power Probe, is alleging its products do not infringe. The following tables summarize Power Probe's non-infringement theories as presented in the complaint.
'853 Patent Infringement Allegations (Claim 1)
| Claim Element (from Independent Claim 1) | Alleged Non-Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a test load... the test load replacing a component of the circuit under load | The accused products are designed and intended to test a complete circuit without replacing any component. The user manual instructs testing a component while it is operating under power within the complete circuit. | ¶51, ¶52, ¶98 | col. 12:55-59 |
| a switch adapted to short circuit test leads of the voltmeter through the test load | The accused products do not employ or incorporate a switch for this purpose. The complaint alleges the products do not short circuit any portion of the circuit under test or create a new path for current via a switch. | ¶54, ¶55, ¶98 | col. 12:59-62 |
'853 Patent Infringement Allegations (Claim 8)
| Claim Element (from Independent Claim 8) | Alleged Non-Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| removing a component from the circuit under load | The accused products are used to test circuits with all components installed and operating; no component is removed. | ¶61, ¶62, ¶108 | col. 13:9-10 |
| closing a switch to short circuit inputs of the digital voltmeter through a test load | The accused products do not employ a switch to short circuit voltmeter inputs through a test load. The complaint alleges the user does not use any switch to complete a short circuit. | ¶64, ¶66, ¶108 | col. 13:12-14 |
| ...the test load completing the circuit under load. | Because the original circuit remains complete with all of its components, the test load does not "complete" the circuit. | ¶61, ¶99, ¶108 | col. 13:15-18 |
- Identified Points of Contention:
- Scope Questions: The primary dispute appears to center on the meaning of "replacing a component." The complaint presents a theory that this requires physical removal of a component and substitution with the test device. A counterargument might suggest that applying an external load that electrically dominates the circuit's existing load could be considered functionally "replacing" it. The extensive prosecution history detailed in the complaint, where the applicant specifically distinguished the invention from prior art by adding this limitation, will be central to this argument (Compl. ¶26-43).
- Technical Questions: A key question is whether the internal circuitry of the accused products performs the function of "a switch adapted to short circuit test leads... through the test load," even if it does not use a discrete, manually operated switch as depicted in the patent's figures (’853 Patent, Fig. 1). The complaint alleges the accused products do not create a new path for current or short circuit any portion of the circuit, raising a factual dispute about their precise mode of operation compared to the claim language (Compl. ¶55, 65).
V. Key Claim Terms for Construction
The Term: "replacing a component of the circuit under load"
Context and Importance: This limitation appears in every independent claim and was added during prosecution to overcome prior art (Compl. ¶26, 33, 43). Its construction is therefore critical to the non-infringement analysis. Practitioners may focus on this term because the Plaintiff's entire non-infringement theory rests on the argument that its products test complete circuits without replacing components.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent's stated goal is to enable "dynamic testing" (’853 Patent, col. 2:21-22). A party could argue that any method that applies a load to achieve a dynamic test, even without physical removal, falls within the spirit of the invention.
- Evidence for a Narrower Interpretation: The complaint highlights prosecution history where the applicant distinguished the invention from the Hanson patent by stating "Hanson is not replacing a component" and that the invention involves the "removal of a component and the use of the test leads to apply a load... in place of the removed component" (Compl. ¶29, 38). The patent specification itself discusses testing at the "location of a removed component" and coupling leads to terminals where a component was before its "removal" (’853 Patent, col. 2:10-12; col. 5:67-6:2).
The Term: "a switch adapted to short circuit test leads... through the test load"
Context and Importance: This is the second pillar of the Plaintiff's non-infringement argument (Compl. ¶54, 64). The presence and function of such a "switch" in the accused products is a primary point of dispute.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party could argue that "switch" is a functional term and that any electronic mechanism, whether manual or automatic, that achieves the claimed electrical result (coupling the test load across the leads) meets the limitation.
- Evidence for a Narrower Interpretation: The patent's figures consistently depict a distinct, physical switch (e.g., element 130 in Fig. 1, 2, 5) separate from the voltmeter and test load. The specification describes turning the switch "on" and "off" to couple and decouple the load, language that suggests a discrete user action rather than an automatic function (’853 Patent, col. 6:25-26). The complaint alleges the accused products operate automatically without a user manipulating such a switch (Compl. ¶56, 66).
VI. Other Allegations
- Indirect Infringement: The complaint seeks a declaration of non-infringement for both direct and indirect infringement (Compl., Prayer for Relief ¶1, 2). The factual basis for this is the assertion that because no direct infringement occurs, there can be no indirect infringement. The complaint further alleges that Plaintiff "does not advise end users to replace any component" or "use a test load," which would negate the intent element required for inducement (Compl. ¶50, 60).
- Willful Infringement: Not alleged, as this is a declaratory judgment action filed by the accused infringer.
VII. Analyst’s Conclusion: Key Questions for the Case
A core issue will be one of claim scope defined by prosecution history: Does the phrase "replacing a component," which was added to overcome prior art, require the physical removal of a part from the circuit, as Plaintiff alleges its products avoid? Or can the term be construed more broadly to cover a functional, electrical replacement where an external load is applied to a complete, intact circuit?
A central question will be one of technical and functional equivalence: Do the accused products, which the complaint claims test circuits automatically without creating new current paths, contain an internal mechanism that functions as "a switch adapted to short circuit test leads... through the test load" as required by the claims? The case may turn on whether the integrated, automated functionality of the accused products is technically distinct from the discrete, switched system described and claimed in the patent.