DCT
8:25-cv-02251
Mems Innovations LLC v. TDK Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: MEMS Innovations, LLC (Texas)
- Defendant: TDK Corporation (Japan); TDK Corp of America (California); InvenSense, Inc. (Delaware)
- Plaintiff’s Counsel: ONE LLP
- Case Identification: 8:25-cv-02251, C.D. Cal., 10/06/2025
- Venue Allegations: Plaintiff alleges venue is proper because TDK Corporation is an alien corporation subject to suit in any district; TDK Corporation of America and InvenSense, Inc. allegedly maintain regular and established places of business in the district and have committed acts of infringement there.
- Core Dispute: Plaintiff alleges that Defendants’ ultrasonic Time-of-Flight sensors infringe two patents related to the structure and manufacturing of piezoelectric microelectromechanical systems (MEMS) transducers.
- Technical Context: The lawsuit concerns MEMS technology, a process for creating microscopic mechanical devices, used here to build miniature acoustic components for applications such as proximity sensing, robotics, and consumer electronics.
- Key Procedural History: The complaint discloses a prior lawsuit involving the same patents and parties (with the exception of InvenSense, which was allegedly involved in settlement discussions) filed in the Eastern District of Texas on November 8, 2022. That case was dismissed without prejudice on May 1, 2023, following an agreement to pursue an out-of-court resolution, which was ultimately unsuccessful. This history forms the basis for Plaintiff’s willfulness allegations.
Case Timeline
| Date | Event |
|---|---|
| 2007-12-07 | U.S. Patent No. 7812505 Priority Date |
| 2007-12-18 | U.S. Patent No. 8114697 Priority Date |
| 2010-10-12 | U.S. Patent No. 7,812,505 Issued |
| 2012-02-14 | U.S. Patent No. 8,114,697 Issued |
| 2022-11-08 | Prior lawsuit filed by Plaintiff in E.D. Texas |
| 2023-05-01 | Prior E.D. Texas lawsuit dismissed without prejudice |
| 2025-10-06 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,812,505 - "Piezoelectric Microspeaker Using Microelectromechanical Systems and Method of Manufacturing the Same"
The Invention Explained
- Problem Addressed: The patent’s background section states that conventional MEMS microspeakers can suffer from low output and that their resonance frequencies often fall within the audible range, creating undesirable noise ('505 Patent, col. 1:36-44).
- The Patented Solution: The invention introduces a "resonance change unit" patterned onto the structure, typically on the bottom surface of the elastic layer supporting the piezoelectric material ('505 Patent, col. 2:6-9). This unit, described in an embodiment as a protrusion, alters the stiffness and mass of the device’s diaphragm, which is intended to shift the resonance frequency out of the audible band and create a more uniform sound output ('505 Patent, col. 4:26-30, 4:51-54).
- Technical Importance: The invention provides a method for tuning the acoustic performance of a MEMS speaker by incorporating a specific structural feature during the manufacturing process to control resonance.
Key Claims at a Glance
- The complaint asserts independent claim 1 ('505 Patent, col. 7:60-65; Compl. ¶27).
- Essential elements of claim 1 include:
- A piezoelectric microspeaker using microelectromechanical systems (MEMS), comprising:
- a piezoelectric layer disposed on an elastic thin layer; and
- a resonance change unit patterned on one of a bottom surface of the elastic thin layer and a top surface of the piezoelectric layer.
- The complaint alleges infringement of "one or more claims" of the patent (Compl. ¶27).
U.S. Patent No. 8,114,697 - "Piezoelectric Microphone, Speaker, Microphone-Speaker Integrated Device and Manufacturing Method Thereof"
The Invention Explained
- Problem Addressed: The patent addresses the problem of low output in conventional micro-speakers ('697 Patent, col. 1:42-43).
- The Patented Solution: The invention proposes a piezoelectric plate constructed with two distinct regions of different thicknesses: a thicker "piezoelectric strain region" where the driving electrode is located, and a thinner "vibration region" ('697 Patent, Abstract). The thinner vibration region is designed to be more flexible, allowing it to vibrate more readily in response to the forces generated in the thicker strain region, thereby increasing the speaker's acoustic output ('697 Patent, col. 6:29-43).
- Technical Importance: This differential-thickness design provides a way to enhance speaker output by engineering a more flexible vibrating membrane while maintaining the structural integrity of the core piezoelectric driver.
Key Claims at a Glance
- The complaint asserts independent claim 10 ('697 Patent, col. 15:16-28; Compl. ¶47).
- Essential elements of claim 10 include:
- A piezoelectric speaker comprising:
- a silicon substrate;
- an insulating layer provided over the silicon substrate;
- a piezoelectric plate provided over the insulating layer, the piezoelectric plate including a piezoelectric strain region and a vibration region; and
- a mating electrode provided in the piezoelectric strain region of the piezoelectric plate,
- wherein the piezoelectric plate is thinner in the vibration region than in the piezoelectric strain region.
- The complaint alleges infringement of "one or more claims" of the patent (Compl. ¶47).
III. The Accused Instrumentality
Product Identification
- The accused products are the "TDK Ultrasonic Sensors," including the Chirp CH101, CH201, ICU-10201, ICU-20201, ICU-30201, and USSM1.0 PLUS-FS models, as well as other similar TDK products (Compl. ¶¶28, 48). The Chirp CH101 sensor is used as the exemplary accused product for infringement allegations.
Functionality and Market Context
- The accused products are identified as ultrasonic Time-of-Flight (ToF) sensors that use MEMS transducers to generate and detect sound waves (Compl. ¶¶17, 28). They are marketed for a range of applications, including proximity sensing, object detection, robotics, drones, and augmented reality hardware (Compl. ¶¶17-18).
IV. Analysis of Infringement Allegations
'505 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a piezoelectric layer disposed on an elastic thin layer | The CH101 sensor includes a piezoelectric layer (107) disposed on a polysilicon membrane, which functions as an elastic thin layer. | ¶31 | col. 3:4-5 |
| a resonance change unit patterned on one of a bottom surface of the elastic thin layer and a top surface of the piezoelectric layer | The CH101 sensor includes a "setback" patterned on the bottom surface of the polysilicon membrane, which is alleged to define the sensor's resonance frequency. | ¶32 | col. 2:6-9 |
The complaint provides a scanning electron microscope (SEM) cross-section, Figure 2, to show the piezoelectric layer disposed on the polysilicon membrane (Compl. ¶31, p. 11). Another cross-section, Figure 3, illustrates the location of the "setback" structure alleged to be the resonance change unit (Compl. ¶32, p. 12).
- Identified Points of Contention:
- Scope Questions: A central dispute may concern whether the accused "setback" structure meets the definition of a "resonance change unit." The patent specification describes this unit as a "protrusion structure" ('505 Patent, col. 4:51-54), whereas the complaint’s figures depict the "setback" as the edge of an etched cavity that defines the vibrating membrane's perimeter. The case may turn on whether the claim term can be construed to read on a subtractive feature (the edge of a cavity) in addition to an additive or remaining feature (a protrusion).
- Technical Questions: The complaint alleges the "setback" defines the resonance frequency of the device (Compl. ¶32). A factual question for the court may be whether the setback's primary purpose and mechanism of action correspond to that of the claimed "resonance change unit," which is described as varying the stiffness and mass of the diaphragm ('505 Patent, col. 4:63-65).
'697 Patent Infringement Allegations
| Claim Element (from Independent Claim 10) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a silicon substrate | The CH101 includes a silicon substrate. | ¶51 | col. 11:9-10 |
| an insulating layer provided over the silicon substrate | The CH101 includes a polysilicon membrane (603), which is alleged to be the claimed insulating layer. | ¶52 | col. 11:9-12 |
| a piezoelectric plate provided over the insulating layer, the piezoelectric plate including a piezoelectric strain region and a vibration region | The CH101 has a piezoelectric aluminum nitride (AlN) plate (605) over the insulating layer, which allegedly includes distinct piezoelectric strain and vibration regions with different thicknesses. | ¶53 | col. 15:20-22 |
| a mating electrode provided in the piezoelectric strain region of the piezoelectric plate | The CH101 has a top electrode made of molybdenum located in what is alleged to be the thicker piezoelectric strain region of the piezoelectric plate. | ¶53 | col. 15:23-25 |
| wherein the piezoelectric plate is thinner in the vibration region than in the piezoelectric strain region | The piezoelectric plate (605) is alleged to be thinner in its vibration region than in its piezoelectric strain region. | ¶53 | col. 15:26-28 |
To support these allegations, the complaint includes a cross-sectional diagram, Figure 5, identifying the "polysilicon membrane 603" as the insulating layer (Compl. ¶52, p. 18). An SEM image, Figure 6, is provided to show the alleged differential thickness of the piezoelectric plate (605) (Compl. ¶53, p. 19).
- Identified Points of Contention:
- Scope Questions: The complaint identifies a "polysilicon membrane" as the claimed "insulating layer" (Compl. ¶52). A potential point of contention may be whether polysilicon, a form of silicon, qualifies as an "insulating layer" in the context of the patent, which discloses embodiments using silicon oxide or silicon nitride ('697 Patent, col. 11:19-22).
- Technical Questions: Infringement of the final limitation hinges on the allegation that the piezoelectric plate has intentionally designed regions of different thicknesses. A factual dispute may arise over whether the thickness variation shown in the complaint's SEM image (Figure 6) is a deliberate feature corresponding to distinct "strain" and "vibration" regions, or an incidental artifact of the MEMS fabrication process.
V. Key Claim Terms for Construction
Term ('505 Patent): "resonance change unit"
- Context and Importance: This term is central to the '505 Patent's asserted claim, as infringement depends entirely on whether the accused "setback" structure falls within its scope. Practitioners may focus on whether this term is limited to the specific embodiment described in the patent.
- Intrinsic Evidence for a Broader Interpretation: The claim language broadly recites a "unit patterned on" a surface without specifying its form (e.g., additive or subtractive). The stated purpose is to "change a resonance frequency" ('505 Patent, col. 2:11-13), which could support an interpretation covering any feature patterned to achieve that result.
- Intrinsic Evidence for a Narrower Interpretation: The specification describes the unit as a "protrusion structure" formed by "leaving the silicon during the etching of the silicon substrate" ('505 Patent, col. 4:51-56). Figure 1 also depicts element 110 as a protrusion. This could support an argument that the term should be limited to such protruding structures.
Term ('697 Patent): "vibration region"
- Context and Importance: The definition of this term is critical because the core limitation of claim 10 is the relative thickness of the "piezoelectric plate" in the "vibration region" versus the "piezoelectric strain region".
- Intrinsic Evidence for a Broader Interpretation: The claim itself does not specify the location or shape of the "vibration region", only that it is part of the piezoelectric plate and is thinner than the strain region. This may support a construction that does not require it to be in any specific location, such as the periphery.
- Intrinsic Evidence for a Narrower Interpretation: The specification discusses thinning an "outer circumferential portion" of the piezoelectric layer to make it vibrate more easily ('697 Patent, col. 6:6-11). Furthermore, dependent claim 11 explicitly adds the limitation "wherein the vibration region is formed at an outer portion of the piezoelectric strain region." This may be used to argue that the term "vibration region" in claim 10 should be understood as being located at the outer portion of the device.
VI. Other Allegations
- Indirect Infringement: The complaint alleges induced infringement for both patents, stating that Defendants provide promotional literature, datasheets, and technical support that encourage and instruct customers to incorporate the accused sensors into infringing end products like smart home devices, robotics, and automobiles (Compl. ¶¶33, 37-38, 54, 58-59).
- Willful Infringement: The willfulness allegations are based on knowledge allegedly obtained from a prior lawsuit filed on November 8, 2022. The complaint alleges that TDK Corporation and TDK Corporation of America had actual knowledge of the patents and their infringement since at least that date, and that InvenSense, Inc. had knowledge prior to the lawsuit's dismissal on May 1, 2023, due to its involvement in settlement discussions (Compl. ¶¶23, 34-35, 55-56).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of structural scope: can the term "resonance change unit" from the ’505 Patent, described in the specification as a "protrusion," be construed to cover the accused "setback," which appears to be the edge of an etched cavity?
- A key evidentiary question will be one of functional design: does the differential thickness observed in the accused sensors' piezoelectric layer represent an intentional design creating functionally distinct "strain" and "vibration" regions as required by the ’697 Patent, or is it an incidental manufacturing artifact without the claimed functional purpose?
- Given the specific allegations of notice from a prior lawsuit, a significant question for trial will be willfulness: what evidence will be presented regarding Defendants’ state of mind and conduct after being made aware of the patents-in-suit in 2022?