DCT
4:21-cv-00028
Somero Enterprises Inc v. Ligchine Intl Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Somero Enterprises, Inc. (Delaware)
- Defendant: Ligchine International Corporation (Indiana)
- Plaintiff’s Counsel: Honigman LLP
- Case Identification: 1:20-cv-02356, S.D. Ind., 10/02/2020
- Venue Allegations: Venue is alleged to be proper in the Southern District of Indiana because Defendant Ligchine is an Indiana corporation that resides and has its principal place of business in the district.
- Core Dispute: Plaintiff alleges that Defendant’s SpiderScreed line of concrete screeding machines infringes a patent related to wheeled, laser-guided concrete screeding devices.
- Technical Context: The technology concerns automated, mobile equipment used in the construction industry to level and finish uncured concrete surfaces, reducing the need for manual labor.
- Key Procedural History: The complaint alleges that Plaintiff provided Defendant with actual notice of the asserted patent via a letter dated July 30, 2020. Significantly, while not mentioned in the complaint, the provided patent document includes an Inter Partes Review (IPR) Certificate issued by the U.S. Patent and Trademark Office on March 3, 2025. This post-filing proceeding, IPR2024-00051, resulted in the cancellation of claims 1-15 of the asserted patent, which includes all claims asserted in this litigation. This development is potentially dispositive of the case, pending any appeal of the IPR decision.
Case Timeline
| Date | Event |
|---|---|
| 2004-07-26 | '366 Patent Priority Date |
| 2011-10-18 | '366 Patent Issue Date |
| 2017-12-XX | Alleged start of constructive notice via patent marking |
| 2019-01-22 | Defendant introduces the accused SpiderScreed product series |
| 2020-07-30 | Plaintiff sends actual notice letter to Defendant |
| 2020-10-02 | Complaint Filing Date |
| 2023-10-24 | Inter Partes Review (IPR) filed against the '366 Patent |
| 2025-03-03 | IPR Certificate issues, cancelling claims 1-15 of the '366 Patent |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,038,366 - Wheeled Concrete Screeding Device
- Patent Identification: U.S. Patent No. 8,038,366, "Wheeled Concrete Screeding Device," issued October 18, 2011.
The Invention Explained
- Problem Addressed: The patent’s background section describes the process of spreading and striking-off uncured concrete as requiring "considerable manual labor," which is "very labor intensive and costly," particularly for areas where larger, conventional screeding machines cannot be used (ʼ366 Patent, col. 1:35-49).
- The Patented Solution: The invention is a mobile, powered screeding device designed to automate this process. As described in the specification, it comprises a wheeled unit that moves through the uncured concrete, followed by a screed head. The screed head has two main parts: a "grade establishing element" (e.g., a plow or auger) that performs an initial leveling of the concrete based on signals from a laser receiver, and a "vibratable member" that is adjustably attached behind the grade-establishing element and "at least partially floats" on the newly-leveled surface to compact and smooth it (’366 Patent, Abstract; col. 25:11-34).
- Technical Importance: This design sought to reduce the manual labor required for screeding by providing a smaller, more maneuverable, and automated device suitable for a variety of construction jobs (ʼ366 Patent, col. 5:1-6).
Key Claims at a Glance
- The complaint asserts infringement of claims 1-5, with Claim 1 being the sole independent claim asserted (Compl. ¶24).
- The essential elements of independent Claim 1 are:
- A wheeled unit movable through uncured concrete in a screeding direction.
- A screed head supported at the rearward end of the wheeled unit.
- The screed head comprises a "grade establishing element" and a "vibratable member."
- The grade establishing element is vertically adjustable in response to a signal from a laser receiver to establish a "struck-off surface."
- The vibratable member is adjustably attached to the rear of the grade establishing element and "at least partially floats" on and is "at least partially supported" by the struck-off surface.
- The complaint reserves the right to assert additional claims after discovery (Compl. ¶24).
III. The Accused Instrumentality
Product Identification
- The accused instrumentality is Defendant's "SpiderScreed" machine (Compl. ¶14).
Functionality and Market Context
- The complaint describes the SpiderScreed as a "compact, lightweight and maneuverable drive-in system" used for "upper deck concrete and slab-on-grade screeding applications" (Compl. ¶25, p. 6).
- The complaint alleges the SpiderScreed is a laser-guided concrete screed that incorporates features such as a screed head with an auger and a leveling system that uses laser receivers (Compl. ¶25, pp. 7, 10). The complaint includes a photograph of the accused SpiderScreed machine in operation (Compl. ¶15).
IV. Analysis of Infringement Allegations
'366 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a wheeled unit having at least two wheels for movably supporting a frame portion..., wherein said wheeled unit is movable through uncured concrete in a screeding direction; | The accused SpiderScreed is a wheeled unit with at least two wheels that support a frame and is movable through uncured concrete. The complaint provides an image of the machine on a concrete slab. | ¶25, p. 6 | col. 6:27-31 |
| a screed head supported at said rearward end of said frame portion and following behind said wheeled unit..., said screed head comprising a grade establishing element and a vibratable member; | The SpiderScreed has a screed head at its rear that follows the wheeled unit and includes a grade establishing element and a vibratable member. The complaint includes a screenshot from a video showing the screed head. | ¶25, p. 7 | col. 25:18-21 |
| wherein said grade establishing element is generally vertically adjustable responsive to a signal from a laser receiver disposed at said screed head to establish a struck-off surface of the uncured concrete at a desired grade...; | The SpiderScreed's grade establishing element is alleged to be vertically adjustable in response to a signal from a laser receiver on the screed head. The complaint includes a photograph showing the laser receiver mounted on the accused machine. | ¶25, p. 7 | col. 25:22-28 |
| wherein said vibratable member is adjustably attached at a rearward end of said grade establishing element and wherein said vibratable member at least partially floats behind said grade establishing element on the struck-off surface of the uncured concrete...; | The complaint alleges the SpiderScreed has a vibratable member that is adjustably attached to and floats behind the grade establishing element on the leveled concrete surface. A corresponding screenshot points to the vibratable member. | ¶25, p. 8 | col. 25:29-34 |
Identified Points of Contention
- Scope Questions: A central question for infringement, prior to the IPR cancellation, would concern the proper construction of "at least partially floats." The analysis would examine whether the connection and movement of the accused device's vibratable member relative to its grade establishing element meet the claimed functional requirement of "floating," or if it is supported in a manner that falls outside this scope.
- Technical Questions: An evidentiary question would be what proof exists that the accused SpiderScreed's components function in the manner required by the claims. For example, evidence would be needed to show not only the presence of a "grade establishing element" and a "vibratable member," but that the latter is "at least partially supported at the struck-off surface" created by the former, as opposed to being supported entirely by the machine's frame or other structures.
V. Key Claim Terms for Construction
The Term: "at least partially floats"
- Context and Importance: This term is critical as it defines the required dynamic relationship between the vibrating finisher and the newly-leveled concrete. Its construction determines whether a wide range of non-rigid attachments infringe or if only specific, gravity-influenced mechanisms meet the limitation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent uses the term without an explicit, limiting definition, which may support an argument that the term should be given its plain and ordinary meaning, encompassing any arrangement where the vibratable member is not rigidly fixed in its vertical position relative to the grade establishing element.
- Evidence for a Narrower Interpretation: The specification states that because attachment links are "pivotally attached..., the vibrating member may freely float relative to the plow and thus may rest on the forms" (ʼ366 Patent, col. 13:10-14). An accused infringer could argue this language implies a specific type of free, gravity-assisted movement, rather than just any non-rigid connection.
The Term: "grade establishing element"
- Context and Importance: This element performs the initial leveling, creating the "struck-off surface" upon which the "vibratable member" acts. The scope of this term dictates what types of components (e.g., plows, augers, blades) can satisfy this claim limitation.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification discloses multiple embodiments, stating the element "comprises a plow member" (ʼ366 Patent, col. 25:38) or "comprises an auger disposed behind said plow member" (ʼ366 Patent, col. 25:40-41). A patentee would likely argue the term covers any structure that performs the claimed function of establishing the initial grade.
- Evidence for a Narrower Interpretation: A party could argue that the term should be limited to the specific structures disclosed, such as the forward and rearward-facing plows (18a, 18b) or the auger (321), and attempt to distinguish the accused structure on that basis.
VI. Other Allegations
- Willful Infringement: The complaint alleges that Defendant’s infringement is willful, deliberate, and ongoing (Compl. ¶29). This allegation is based on claims of both pre-suit and post-suit knowledge. The complaint alleges constructive notice since at least December 2017 through Plaintiff's patent marking program (Compl. ¶18) and actual notice via a letter sent on July 30, 2020 (Compl. ¶19), followed by Defendant's continued alleged infringement (Compl. ¶28).
VII. Analyst’s Conclusion: Key Questions for the Case
- The primary and overriding issue for this case is one of legal viability: In light of the post-filing IPR decision cancelling all asserted claims of the '366 patent, the central question is whether the lawsuit has any basis to proceed. The infringement analysis becomes moot unless the patent owner successfully appeals the PTAB's decision to the Federal Circuit and has the claims reinstated.
- A secondary, historical question is one of claim scope: Had the patent remained valid, the case would have likely turned on the court's construction of key functional language, particularly whether the accused SpiderScreed's vibratable member "at least partially floats" on the struck-off concrete surface in the manner required by the patent's claims.