DCT
0:17-cv-00173
Air Quality Engineering Inc v. Tri Dim Filter Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Air Quality Engineering, Inc. (Minnesota)
- Defendant: Tri-Dim Filter Corporation (Delaware)
- Plaintiff’s Counsel: Dicke, Billig & Czaja, PLLC
- Case Identification: 0:17-cv-00173, D. Minn., 01/20/2017
- Venue Allegations: Venue is alleged to be proper in the District of Minnesota because the defendant, Tri-Dim, conducts business in the state, is registered with the Minnesota Secretary of State, and has committed acts of infringement in Minnesota, including offering for sale and selling the accused products.
- Core Dispute: Plaintiff alleges that Defendant’s industrial air filtration units infringe a patent related to a method and apparatus for removing mist and smoke generated by machine tools, particularly those using different types of metalworking fluids.
- Technical Context: The technology concerns electrostatic precipitators used to clean contaminated air in industrial settings, a critical function for environmental compliance and worker safety where machine tools generate fine mists from oil-based or water-based coolants.
- Key Procedural History: The complaint alleges a notable history, asserting that one of the patent’s named inventors, Anthony Andolino, left Plaintiff AQE to work for competitor Tri-Dim and subsequently modified Tri-Dim’s products to include the patented features. Plaintiff also alleges it sent a notice letter to Defendant on September 30, 2016, identifying the infringement, and that Defendant refused to cease its allegedly infringing activities on October 28, 2016.
Case Timeline
| Date | Event |
|---|---|
| 2000-11-27 | '611 Patent Priority Date |
| 2001-05 | Inventor Andolino allegedly leaves AQE and joins Tri-Dim |
| 2002-08-06 | '611 Patent Issue Date |
| 2016-07 | AQE purchases an accused Tri-Mist 850 unit |
| 2016-09-30 | AQE sends notice of infringement to Tri-Dim |
| 2016-10-28 | Tri-Dim refuses to cease infringement |
| 2017-01-20 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 6,428,611 - APPARATUS FOR REMOVING MIST, SMOKE AND PARTICLES GENERATED BY MACHINE TOOLS, issued August 6, 2002
The Invention Explained
- Problem Addressed: The patent addresses a problem with electrostatic precipitators used to filter mist from machine tools. While effective for oil-based mists, these systems face "nuisance arcing problems" when used with water-based metalworking fluids, as the collected water mist can short-circuit the high-voltage collector plates, rendering filtration ineffective (’611 Patent, col. 1:30-38).
- The Patented Solution: The invention is an air filtration apparatus with an electrostatic precipitator that can be selectively configured for either oil-based or water-based coolants. The core innovation is circuitry that includes a "collector switch means." When filtering water-based mist, this switch is opened to interrupt the direct high-voltage supply to the collector. The collector is then energized by a lower, induced voltage from the still-active ionizing field. This lower voltage, combined with a reduced airflow speed, is described as sufficient to collect water-based mist particles without causing the short-circuiting that plagues conventional systems (’611 Patent, col. 6:21-32; Abstract).
- Technical Importance: The described solution allows a single electrostatic precipitator unit to be effectively and reliably used for both oil-based and the increasingly common water-based coolants, which previously posed significant operational challenges for this type of filtration technology (’611 Patent, col. 1:28-38).
Key Claims at a Glance
- The complaint asserts infringement of at least Claim 1 (’611 Patent, col. 5:50-6:32; Compl. ¶22).
- The essential elements of independent claim 1 include:
- A housing with an inlet and outlet, adapted for connection to a machine tool.
- A blower device to produce an upward airflow.
- A plurality of mechanical filters adjacent the inlet.
- An electrostatic precipitator downstream of the mechanical filters, including an ionizer and a collector.
- Electrical circuitry with an on-off switch.
- An electrostatic precipitator circuit with a high voltage power supply.
- A "collector switch means" that, when opened, interrupts current to the collector, causing the energized ionizer to "induce a lower output voltage to the collector."
- A blower circuit with an adjustable speed control device, which is adjusted to a specific velocity range (75-175 cfm) when the collector switch is opened for filtering water-based fluid mist.
- The complaint does not explicitly reserve the right to assert dependent claims.
III. The Accused Instrumentality
Product Identification
- The primary accused product is the Tri-Mist 850 filtration unit. The complaint also identifies the Tri-Mist 1000 and Tri-Mist 1400 models "on information and belief" (Compl. ¶22).
Functionality and Market Context
- The Tri-Mist 850 is described as a "compact apparatus for collecting and removing smoke, mist and particles generated by machine tools" (Compl. ¶23a). A key allegation is that the product is sold with a "switch option to allow alternate operation between use with a water-based coolant and use with an oil-based fluid" (Compl. ¶15). The complaint includes a photograph of the accused unit's exterior, identifying it as a "HIGH EFFICIENCY MIST & SMOKE COLLECTOR" (Compl. ¶23b). The complaint further alleges that the product is sold with specific instructions on how to switch the unit between these two modes of operation (Compl. ¶16).
IV. Analysis of Infringement Allegations
'611 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a compact apparatus for collecting and removing smoke, mist and particles generated by machine tools which use water based and petroleum metal working fluids | The Tri-Mist 850 unit is described as a compact apparatus for collecting mist from machine tools using both water-based and petroleum fluids. | ¶23a | col. 5:50-54 |
| a housing having an inlet and an outlet and being adapted to be connected to a machine tool... | The Tri-Mist 850 has a housing with an inlet and outlet, adapted for connection to a machine tool. A photograph shows the inlet opening. | ¶23d, ¶23e | col. 5:55-58 |
| a blower device within said housing for producing an air stream flowing upward... | The unit contains a blower device that produces an upward air stream. | ¶23f | col. 5:59-63 |
| a plurality of mechanical filters within said housing adjacent the inlet... | The unit has multiple mechanical filters near the inlet. A photograph illustrates these filters. | ¶23g, ¶23h | col. 5:64-6:2 |
| an electrostatic precipitator within said housing down stream of the mechanical filters and including an ionizer and a collector... | The unit has an electrostatic precipitator, including an ionizer and collector, located downstream of the mechanical filters. A photograph shows the precipitator. | ¶23i, ¶23j | col. 6:3-6 |
| collector switch means in said electrostatic precipitator circuit... and when opened interrupting current to the collector whereby the ionizing field the energized ionizer will induce a lower output voltage to the collector... | The Tri-Mist 850 has a collector switch. The complaint alleges that when this switch is opened, it interrupts current to the collector, causing the ionizer to induce a lower voltage. Photographs show the switch in both open and closed positions. | ¶23p, ¶23q, ¶23r | col. 6:15-20 |
| a blower circuit... including an electrical speed control device... variously adjustable to control the velocity of the blower device... | The unit has a blower circuit with an adjustable speed control device. A photograph shows the speed control knob. | ¶23t, ¶23u | col. 6:21-26 |
| said speed control device being adjusted to operate the speed of the blower device for producing an air stream having a velocity within the range of 75 cfm to 175 cfm when the collector switch means is opened... | The complaint alleges the speed control is adjusted to operate within the 75-175 cfm range when the collector switch is open to permit effective collection of water-based mist. | ¶23v | col. 6:26-32 |
- Identified Points of Contention:
- Technical Question: A central factual question will be whether the accused "collector switch" operates as claimed. The complaint alleges that opening the switch "will induce a lower output voltage to the collector" (Compl. ¶23p). The defense may argue that the switch simply deactivates the collector entirely, without any "induced" voltage from the ionizer. Proving this specific electrical phenomenon occurs in the accused device will be critical for the plaintiff.
- Scope Question: The claim requires the blower speed to be adjusted "within the range of 75 cfm to 175 cfm" when the switch is open (for water-based fluids). The parties may dispute whether the accused device is actually operated or intended to be operated within this specific numerical range under those conditions. The complaint alleges it is (Compl. ¶23v), but this will be subject to testing and evidence.
V. Key Claim Terms for Construction
The Term: "collector switch means"
- Context and Importance: This term is the central feature of the asserted claim, distinguishing the invention from prior art. Its construction will determine whether a simple on-off switch for the collector infringes, or if the switch must perform the more complex function of enabling an "induced voltage" mode. Practitioners may focus on this term because the infringement case hinges on whether the accused switch performs the specific function disclosed in the patent's specification.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim uses the general term "switch means," which could be argued to encompass any structure that performs the function of interrupting current to the collector.
- Evidence for a Narrower Interpretation: The specification repeatedly and explicitly links the opening of the switch to a specific outcome: "When switch 62 is opened, current is interrupted to the collector unit... The electric field generated by the ionizer unit induces current into the collector unit at a substantially lower voltage" (’611 Patent, col. 6:23-27). This suggests the term is a means-plus-function limitation under 35 U.S.C. § 112(f), where the function is not just "interrupting current" but also "whereby the ionizing field... will induce a lower output voltage."
The Term: "induce a lower output voltage"
- Context and Importance: This functional language is inextricably linked to the "collector switch means" and defines the novel operating mode for water-based fluids. The case may turn on what it means for the ionizer to "induce" voltage in the collector and whether the accused product actually does this.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The term could be interpreted broadly to cover any phenomenon where the collector has some voltage lower than its normal operating voltage after the main supply is cut, even if due to simple capacitance or residual charge.
- Evidence for a Narrower Interpretation: The specification describes a specific mechanism: "The electric field generated by the ionizer unit induces current into the collector unit at a substantially lower voltage (2500 Vdc rather than 4150 Vdc)" (’611 Patent, col. 6:25-27). This provides a specific physical explanation and numerical example, suggesting the term requires an active electrical field induction, not just a passive state.
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Tri-Dim induces infringement by selling the Tri-Mist 850 with "specific instructions on how to switch the unit between use with water-based coolant and use with oil" (Compl. ¶16). This allegation is supported by reference to a one-page insert shipped with the product (Compl. ¶16, Exhibit D).
- Willful Infringement: The willfulness claim is supported by several allegations: (1) Tri-Dim allegedly hired a named inventor of the ’611 Patent, who then "modified the Tri-Dim products to include a collector switch option" (Compl. ¶11, ¶16); (2) Tri-Dim was put on actual notice of infringement via a letter from AQE's counsel on September 30, 2016 (Compl. ¶19); and (3) Tri-Dim allegedly refused to cease its infringing conduct after receiving notice (Compl. ¶20).
VII. Analyst’s Conclusion: Key Questions for the Case
- A key evidentiary question will be one of technical operation: Does the accused Tri-Mist 850’s "collector switch," when set for water-based fluids, merely de-energize the collector, or does it implement the specific, two-part function required by Claim 1—interrupting the direct high-voltage supply while also allowing the ionizer field to "induce a lower output voltage" in the collector? Proving this induced voltage phenomenon will be a central technical hurdle for the plaintiff.
- A second core issue will be one of intent: The complaint presents a compelling narrative for willfulness, alleging that a former employee and inventor on the patent-in-suit moved to a direct competitor and incorporated the patented technology into the accused products. Should infringement be found, the resolution of these allegations will be critical to the determination of willfulness and potential enhanced damages.
- Finally, the case may involve a battle over quantification: The claim recites a specific airflow range of "75 cfm to 175 cfm" for the water-based mode. The parties will likely contest whether the accused device's instructions and normal operation fall within this numerically-defined limitation, which could be dispositive for literal infringement.