DCT
6:25-cv-00388
Mems Innovations LLC v. TDK Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: MEMS INNOVATIONS, LLC (Texas)
- Defendant: TDK CORPORATION (Japan); TDK U.S.A. CORPORATION (New York); TDK CORPORATION OF AMERICA (California)
- Plaintiff’s Counsel: ONE LLP
- Case Identification: 6:25-cv-00388, E.D. Tex., 10/06/2025
- Venue Allegations: Plaintiff alleges venue is proper for TDK Corporation as an alien corporation, and for the U.S. subsidiaries based on alleged acts of infringement and regular and established places of business within the Eastern District of Texas.
- Core Dispute: Plaintiff alleges that Defendant’s PiezoListen series of piezoelectric speakers infringes a patent related to the construction of speakers with multi-layered acoustic diaphragms.
- Technical Context: The technology concerns compact, thin-form-factor piezoelectric speakers designed for integration into modern slim electronic devices like laptops and displays, where traditional dynamic speakers may be too bulky.
- Key Procedural History: The patent-in-suit was originally assigned to the Electronics and Telecommunications Research Institute (ETRI) in Korea. Plaintiff MEMS Innovations asserts it is the exclusive licensee with the right to enforce the patent.
Case Timeline
| Date | Event |
|---|---|
| 2010-12-10 | ’776 Patent Priority Date |
| 2014-10-28 | ’776 Patent Issue Date |
| 2025-10-03 | Alleged date of written notice of infringement to Defendants |
| 2025-10-06 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,873,776 - “Piezoelectric Speaker”
- Patent Identification: U.S. Patent No. 8,873,776, “Piezoelectric Speaker,” issued October 28, 2014.
The Invention Explained
- Problem Addressed: The patent’s background section describes challenges in commercializing piezoelectric speakers for modern thin devices, noting that prior art speakers often output low sound pressure, struggle to reproduce low-frequency sounds, and can suffer from sound distortion due to resonance or the use of metal diaphragms (’776 Patent, col. 1:38-42; col. 2:10-21).
- The Patented Solution: The invention proposes a piezoelectric speaker that uses a composite "acoustic diaphragm" made of a "hetero material" to improve sound quality, particularly in the low-frequency range. This diaphragm is constructed from at least two layers with different physical properties: a first layer with a low Young's modulus (e.g., rubber or silicon) to absorb distortion and improve low-frequency reproduction, and a second layer with a high Young's modulus (e.g., plastic or metal) to improve frequency response characteristics (’776 Patent, Abstract; col. 4:66-col. 5:14). This layered structure is illustrated in Figure 1 of the patent.
- Technical Importance: This approach aims to provide the benefits of a thin, light piezoelectric speaker while overcoming its traditional acoustic shortcomings, making it more competitive with conventional dynamic speakers for use in slim electronics (’776 Patent, col. 2:51-59).
Key Claims at a Glance
- The complaint asserts independent claim 1 and reserves the right to assert additional claims (’776 Patent, Compl. ¶24).
- Claim 1 requires:
- a piezoelectric layer that converts electrical signals into oscillation
- an electrode disposed on the piezoelectric layer
- an acoustic diaphragm made of a hetero material, which includes a first acoustic diaphragm and a second acoustic diaphragm, disposed under the piezoelectric layer
- a frame attached to the acoustic diaphragm to enclose a side of it
- a specific physical property: the Young's modulus of the first acoustic diaphragm is lower than the Young's modulus of the second acoustic diaphragm
III. The Accused Instrumentality
Product Identification
- The TDK PiezoListen PHU Series of piezoelectric speakers, with product number PHUA3015-049B-00-000 identified as a representative example (the "Infringing Products") (Compl. ¶¶ 23-24).
Functionality and Market Context
- The complaint alleges the PiezoListen speakers are components designed to be attached directly to other surfaces, such as the display of a laptop or television, causing that surface to vibrate and produce sound (Compl. ¶30). This design eliminates the need for traditional speaker grilles. The complaint presents a TDK illustration of a PiezoListen speaker attached behind a laptop screen, turning the screen into the sound-emitting surface (Compl. ¶30, Fig. 6). Plaintiff alleges TDK markets these products for use in televisions, displays, mobile devices, and smart speakers (Compl. ¶35).
IV. Analysis of Infringement Allegations
’776 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a piezoelectric layer that converts electrical signals into oscillation of the piezoelectric layer and outputs sound | The accused product is a piezoelectric speaker that includes a "piezo+electrode stack" containing piezoelectric layers. An annotated scanning electron microscope (SEM) image is provided to show these layers (Compl. ¶28, Fig. 4). | ¶¶ 26, 28-29 | col. 4:7-13 |
| an electrode that is disposed on a top surface or a bottom surface of the piezoelectric layer to apply the electrical signals to the piezoelectric layer | The SEM images in the complaint purport to show individual electrode layers within the accused product's stack (Compl. ¶29, Fig. 5). | ¶¶ 28-29 | col. 4:35-40 |
| an acoustic diaphragm that is made of a hetero material including a first acoustic diaphragm and a second acoustic diaphragm and disposed under the bottom surface of the piezoelectric layer | Plaintiff alleges that when the accused speaker is attached to a display as instructed by TDK, the display itself functions as the claimed acoustic diaphragm. The various layers of the display (e.g., glass, polarizers) allegedly form the "first" and "second" diaphragms (Compl. ¶33, Fig. 10). | ¶¶ 30, 33-34 | col. 4:62-65 |
| a frame that is attached to the acoustic diaphragm to enclose a side of the acoustic diaphragm | The complaint alleges that the frame of the end-product device (e.g., a laptop bezel or TV frame) that holds the display in place serves as the claimed frame. An illustration shows the accused speaker installed in a laptop (Compl. ¶32, Fig. 6). | ¶¶ 32 | col. 5:28-34 |
| wherein a Young's modulus of the first acoustic diaphragm is lower than a Young's modulus of the second acoustic diaphragm | The complaint alleges that the different materials comprising the layers of a typical LCD or OLED display inherently have different Young's moduli, thereby satisfying this limitation (Compl. ¶34, Fig. 10). | ¶34 | col. 5:1-14 |
Identified Points of Contention
- Scope Questions: The central dispute may concern the definition of the claimed "piezoelectric speaker." Does the claim require the "acoustic diaphragm" to be an integral part of the speaker as sold, or can it be read to cover a system where the accused component is attached to a separate structure (like a display screen) that then performs the diaphragm's function? The complaint’s theory relies on the latter interpretation.
- Technical Questions: Does the incidental layering of a standard commercial display screen (e.g., glass, polarizers, backplane) meet the claim requirement of a "hetero material including a first acoustic diaphragm and a second acoustic diaphragm" with a specific relationship between their Young's moduli, as described in the patent? The complaint's visual evidence shows the accused speaker attached to a display, which is then diagrammed as the multi-layered diaphragm (Compl. ¶¶ 31, 33, Figs. 7, 10). A question for the court will be whether this combination matches the patented structure.
V. Key Claim Terms for Construction
- The Term: "an acoustic diaphragm that is made of a hetero material including a first acoustic diaphragm and a second acoustic diaphragm"
- Context and Importance: This term is the crux of the infringement allegation. The complaint's theory is that a third-party object (a display screen) becomes the "acoustic diaphragm" upon installation of the accused product. The definition of whether the diaphragm must be an integral component of the speaker or can be a separate, user-supplied element will be critical.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim requires the diaphragm to be "disposed under the bottom surface of the piezoelectric layer," which could be argued to describe a final assembled state rather than the condition of the product as sold. Plaintiff may argue that because TDK instructs users to create this final state, the limitation is met.
- Evidence for a Narrower Interpretation: The patent's abstract describes the speaker "including" the acoustic diaphragm, and the detailed description and figures consistently depict the diaphragm (130) as an integrated component of the speaker assembly prior to installation in any larger device (’776 Patent, Abstract; Fig. 1). The specification also details specific materials for the diaphragm layers (e.g., rubber, silicon, plastic, CNT) which may suggest a purpose-built component rather than the incidental layers of a display (’776 Patent, col. 4:66 - col. 5:14).
VI. Other Allegations
- Indirect Infringement: The complaint heavily emphasizes an inducement theory, alleging that TDK knowingly encourages and provides instructions for its customers to combine the PiezoListen speakers with displays in an infringing manner. Allegations cite TDK datasheets, application notes, and promotional materials (Compl. ¶¶ 30-31, 35, 40-41). Contributory infringement is also alleged, stating the product is a material component of the invention specifically adapted for this infringing use and is not a staple article of commerce (Compl. ¶36).
- Willful Infringement: The complaint alleges Defendants had knowledge of the ’776 Patent at least as of a written notice dated October 3, 2025, and as of the date the complaint was filed, forming a basis for post-suit willfulness (Compl. ¶¶ 37-38).
VII. Analyst’s Conclusion: Key Questions for the Case
This case appears to present fundamental questions of claim scope and the boundary between component supply and direct infringement. The outcome may depend on the court's answers to the following:
- A core issue will be one of definitional scope: can the term "acoustic diaphragm," which the patent’s figures depict as an integral part of a speaker, be construed to cover a separate, user-supplied product like a computer display to which the accused component is attached post-sale?
- A second issue will be one of structural identity: do the pre-existing, multi-functional layers of a standard LCD or OLED screen constitute the purpose-built, two-part "hetero material" diaphragm with specific acoustic properties as claimed in the patent?
- Finally, the case raises a question of liability for combination systems: if direct infringement occurs only when an end-user combines the accused speaker with a display, the case will likely turn on the strength of evidence that Defendant specifically intended to induce this combination, as alleged through its marketing and instructional materials.