DCT
2:23-cv-00477
Phenix Longhorn LLC v. Au Optronics Corp
Key Events
Amended Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Phenix Longhorn LLC (Texas)
- Defendant: AU Optronics Corporation (Taiwan); Hisense Electronica Mexico, S.A. de C.V. (Mexico); Hisense USA Corporation (Georgia); Hisense Visual Technology Co., Ltd. (P.R. China)
- Plaintiff’s Counsel: Findlay Craft, P.C.; Womble Bond Dickinson (US) LLP
- Case Identification: 2:23-cv-00477, E.D. Tex., 05/12/2025
- Venue Allegations: Venue is alleged to be proper for the foreign defendants under 28 U.S.C. § 1391(c). For domestic defendant Hisense USA, venue is asserted based on it having a regular and established place of business within the district and having committed acts of infringement there.
- Core Dispute: Plaintiff alleges that Defendants’ LCD panel modules and the televisions that incorporate them infringe two patents related to programmable integrated circuits that generate gamma reference voltages to calibrate LCDs.
- Technical Context: The technology involves specialized integrated circuits ("Pgamma chips") that correct for non-linearities and manufacturing variations in LCDs, a critical function for achieving high picture quality in modern televisions and displays.
- Key Procedural History: The complaint notes that the '305 Patent was subject to an Inter Partes Review (IPR) proceeding where the Patent Trial and Appeal Board (PTAB) denied the challenger's petition for institution, leaving the patent's claims intact. The complaint also mentions prior litigation in the district against Defendant Hisense Visual where jurisdiction was not contested.
Case Timeline
| Date | Event |
|---|---|
| 2002-03-01 | Inventors found semiconductor company Alta Analog, Inc. |
| 2003-06-11 | Priority date for '305 and '788 Patents |
| 2003-01-01 | Alta Analog allegedly began engaging with Defendant AUO |
| 2007-06-19 | U.S. Patent No. 7,233,305 issues |
| 2007-11-01 | Alta allegedly presented the '305 Patent to AUO |
| 2009-07-07 | U.S. Patent No. 7,557,788 issues |
| 2012-06-12 | Alta allegedly provided AUO with data sheets including both Asserted Patents |
| 2015-07-01 | Hisense entities allegedly acquired the Sharp Mexico manufacturing facility |
| 2019-01-24 | PTAB denies institution of IPR against the '305 Patent |
| 2025-05-12 | Fourth Amended Complaint filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,233,305 - "Gamma Reference Voltage Generator," Issued June 19, 2007
The Invention Explained
- Problem Addressed: The patent addresses the problem that LCD panel manufacturing results in variations in display characteristics, and the relationship between applied voltage and pixel brightness is non-linear (Compl. ¶31). The traditional solution involved manually selecting and installing discrete resistors ("Select-On-Test" resistors) to fine-tune the gamma correction voltages for each panel, a process described as manual, expensive, and a barrier to automated production ('305 Patent, col. 1:29-45).
- The Patented Solution: The invention is an integrated circuit that replaces the manual resistor-based system. It contains programmable, non-volatile memory cells to store multiple sets (or "banks") of gamma reference voltage values ('305 Patent, Abstract). Once programmed, the circuit continuously outputs the correct voltages to the display's source drivers, retaining the values even when power is off, thereby enabling automated calibration and enhanced flexibility ('305 Patent, col. 2:16-28).
- Technical Importance: This technology allowed for the automation of a critical step in LCD manufacturing, which is alleged to have streamlined production, reduced costs, and improved picture quality by enabling precise, reprogrammable gamma correction (Compl. ¶34).
Key Claims at a Glance
- The complaint asserts infringement of at least independent Claim 1 and dependent Claims 2 and 5 (Compl. ¶85, ¶132).
- Independent Claim 1 recites an integrated circuit with the following key elements:
- a plurality of non-volatile storage cells;
- circuits for programming coupled to a multiplexer for addressing and programming the storage cells;
- drivers connected to the storage cells and outputs;
- inputs connected to the multiplexer for addressing the storage cells;
- wherein the output voltage signals are gamma reference voltage signals;
- wherein the non-volatile storage cells are organized into two or more banks, each containing a predetermined gamma reference voltage signal display condition; and
- a "means to switch between the banks" based on external signals.
- The complaint reserves the right to assert additional claims (Compl. ¶74, ¶85).
U.S. Patent No. 7,557,788 - "Gamma Reference Voltage Generator," Issued July 7, 2009
The Invention Explained
- Problem Addressed: The '788 Patent, a continuation of the '305 Patent, addresses the same underlying problem of compensating for panel-to-panel manufacturing variations to achieve a desired gamma curve ('788 Patent, col. 7:24-27).
- The Patented Solution: This patent claims a method for calibrating an LCD. The method comprises the steps of: providing a display with reprogrammable and non-volatile gamma reference control capability (such as the circuit from the '305 Patent); testing the display using an optical sensor that is separate from the display; varying the gamma voltage levels using a control circuit that is also separate from the display; optimizing these voltage levels using a predetermined algorithm executed by a means that is separate from the display; and storing the resulting optimized voltage levels in the display's gamma reference control capability ('788 Patent, col. 7:28-42).
- Technical Importance: The claimed method provides a systematic and automated process for calibrating displays during manufacturing, using feedback from external equipment to tune the display to a precise, desired standard, thereby improving quality control (Compl. ¶34; '788 Patent, col. 7:20-25).
Key Claims at a Glance
- The complaint asserts infringement of at least independent Claim 1 (Compl. ¶106, ¶142).
- Independent Claim 1 recites a method of calibrating a liquid crystal display with the following key steps:
- providing the display with electrically reprogrammable and non-volatile gamma reference control capability;
- testing the display with at least one sensor with optical input, where the sensor is separate from the display;
- varying gamma reference voltage levels on the display's columns using a control circuit that is separate from the display;
- optimizing the voltage levels using means for executing a predetermined algorithm, where the means is separate from the display; and
- storing the optimized voltage levels in the gamma reference control capability.
- The complaint reserves the right to assert additional claims (Compl. ¶95, ¶106).
III. The Accused Instrumentality
Product Identification
- The complaint identifies two categories of accused instrumentalities: "Infringing Panel Modules" and "Infringing TV Products" (Compl. ¶55-58).
- The Infringing Panel Modules are described as LCD panel modules manufactured by Defendant AUO that include a timing and control (TCON) board with a programmable gamma integrated circuit ("Pgamma chip") with at least two banks. Specific accused Pgamma chips include the AUO-G201, AUO-G301, and AUO-G1422 (Compl. ¶55).
- The Infringing TV Products are finished televisions that incorporate the Infringing Panel Modules. The complaint lists numerous models from manufacturers including Hisense, Samsung, Vizio, TCL, and others (Compl. ¶56-58).
Functionality and Market Context
- The complaint alleges the accused Pgamma chips provide the functionality of producing gamma reference voltages from programmable, non-volatile storage cells organized into banks, which are then used to calibrate the LCD panel (Compl. ¶78, ¶89). The complaint alleges that Defendant AUO tests and calibrates these modules for incorporation into finished televisions destined for the U.S. market (Compl. ¶61).
- The complaint includes a six-panel image illustrating how different gamma correction values alter the curvature, color, and contrast of a woman's and a child's face on a display (Compl. ¶33).
- The Infringing TV Products are alleged to be popular consumer items sold through major U.S. retailers, representing a significant revenue stream for the Defendants (Compl. ¶15, ¶49-52, ¶62).
IV. Analysis of Infringement Allegations
’305 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| An integrated circuit for producing Voltage signals on a plurality of outputs comprising: a plurality of non-volatile storage cells; | The Infringing Panel Modules are alleged to contain a Pgamma chip (e.g., AUO-G201) with non-volatile storage cells for producing voltage signals. | ¶78, ¶89 | col. 2:20-23 |
| circuits for programming coupled to a multiplexer for addressing and programming said storage cells... | The accused Pgamma chip allegedly includes circuits for programming coupled to a multiplexer for addressing and programming the storage cells. | ¶78, ¶89 | col. 3:6-14 |
| drivers connected to said storage cells and to the plurality of outputs; | The accused Pgamma chip's drivers are alleged to connect to the storage cells and outputs to drive the display columns. | ¶78, ¶89 | col. 3:1-5 |
| wherein said non-volatile storage cells are organized into two or more banks of cells... | The accused Pgamma chip is alleged to have at least two banks of non-volatile storage cells, with each bank containing a predetermined gamma reference voltage display condition. | ¶55, ¶78, ¶89 | col. 5:50-54 |
| and means to switch between the banks based on one or more external signals is provided on said integrated circuit. | The banks in the accused Pgamma chip are allegedly able to be switched by external signals on the integrated circuit. | ¶78, ¶89 | col. 5:51-54 |
’788 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| A method of calibrating a liquid crystal display...comprising the steps: providing said display with gamma reference control capability which is electrically reprogrammable and non-volatile; | Defendants are alleged to make the Infringing Panel Modules and TV Products using a method that starts by providing a display with the accused Pgamma chip, which has reprogrammable, non-volatile gamma control. | ¶99, ¶110 | col. 7:28-31 |
| testing said display with at least one sensor with optical input, wherein said sensor is separate from said display; | The accused manufacturing method allegedly includes testing the display with a separate optical sensor. | ¶99, ¶110 | col. 7:32-33 |
| varying gamma reference voltage levels on columns of said display by a control circuit, where said control circuit is separate from said display; | The accused manufacturing method allegedly includes varying the gamma voltage levels using a separate control circuit. | ¶99, ¶110 | col. 7:34-36 |
| optimizing said gamma reference voltage levels using means for executing a predetermined algorithm...wherein said means...is separate from said display...; | The accused manufacturing method allegedly includes optimizing the voltage levels using a separate means for executing an algorithm. | ¶99, ¶110 | col. 7:37-40 |
| and storing said gamma reference voltage levels in said gamma reference control capability. | The accused manufacturing method allegedly includes storing the final, optimized gamma reference voltage levels in the Pgamma chip. | ¶99, ¶110 | col. 7:41-42 |
- Identified Points of Contention:
- Technical Questions: For the '305 Patent, a key factual question is whether the accused Pgamma chips, which are identified on "information and belief," actually contain the specific architecture claimed, including "non-volatile storage cells" organized into switchable "banks." The outcome of discovery on the chips' design will be critical.
- Scope Questions: For the '788 Patent's method claim, a central dispute may arise over the term "separate from said display." The parties may contest whether the testing equipment allegedly used by Defendants qualifies as "separate" under the proper construction of the claim.
- Evidentiary Questions: The '788 Patent infringement allegation rests on proving that Defendants practice a specific multi-step method. A primary point of contention will be whether Plaintiff can produce evidence that Defendants, particularly AUO, actually perform or control the performance of all the claimed calibration steps in the specified manner during their manufacturing and testing processes (Compl. ¶61, ¶99).
V. Key Claim Terms for Construction
Term 1: "means to switch between the banks" (’305 Patent, Claim 1)
- Context and Importance: This term is drafted in means-plus-function format under 35 U.S.C. § 112(f). Its scope is not its literal dictionary meaning but is statutorily limited to the specific structure disclosed in the patent's specification for performing the function of switching banks, and equivalents thereof. Infringement will require the accused products to contain that same structure or a structural equivalent.
- Intrinsic Evidence for Interpretation:
- Evidence for a Specific (Narrower) Interpretation: The specification discloses that the function of selecting banks is performed by "three address inputs B0, B1, B2" ('305 Patent, col. 5:51-54). The block diagram in Figure 6 explicitly shows a "Bank Select" logic block receiving inputs B0, B1, and B2. A court will likely construe this term as being limited to this address-line-based selection hardware and its structural equivalents.
Term 2: "separate from said display" (’788 Patent, Claim 1)
- Context and Importance: This limitation, which modifies the "sensor," "control circuit," and "means for executing a predetermined algorithm," is crucial for defining the boundary between the display being calibrated and the equipment used for calibration. Its construction will determine what kind of manufacturing and testing processes fall within the claim's scope.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification's background describes how an "external test apparatus drives the test points" on a display PC board ('788 Patent, col. 1:65-67). This may support an interpretation where "separate" means any equipment that is not part of the final, assembled display product sold to a consumer.
- Evidence for a Narrower Interpretation: A defendant might argue that "separate" requires a higher degree of physical and functional independence, potentially excluding integrated, all-in-one testing stations where the sensor and control circuit are part of a single piece of test machinery. The patent's consistent repetition of "separate" for different components could be argued to emphasize this distinction.
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Defendant AUO induces infringement by supplying the Infringing Panel Modules to downstream manufacturers like Hisense and Samsung, knowing and intending that they will be incorporated into televisions imported and sold in the U.S. (Compl. ¶74). Hisense USA and Hisense Visual are alleged to induce infringement by supplying infringing televisions to distributors and retailers (Compl. ¶138, ¶152).
- Willful Infringement: Willfulness is alleged against all defendants. For AUO, the allegations are based on specific pre-suit knowledge of the patents dating back to at least 2007 and 2012, respectively, through direct communications with the inventor's predecessor company, Alta (Compl. ¶41-42, ¶82, ¶103). For the Hisense defendants, willfulness is alleged based on knowledge since at least the filing of the original complaint in this litigation (Compl. ¶93, ¶140).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of evidentiary proof: Can Plaintiff, through discovery, obtain technical evidence to substantiate its "information and belief" allegations that the accused AUO Pgamma chips possess the specific architecture of the '305 Patent's claims, including non-volatile memory organized into multiple, switchable banks?
- A second key question will be one of process attribution: For the '788 method patent, can Plaintiff prove that Defendants' manufacturing and calibration process, as actually practiced, includes every step of the claimed method? The case may turn on evidence showing whether Defendants use a "separate" optical sensor and control circuit in the manner required by the claim.
- Finally, the dispute will likely involve a legal question of claim scope: How the court construes the means-plus-function term "means to switch between the banks" will be critical. The infringement analysis for this element will focus on whether the accused devices contain circuitry that is structurally equivalent to the specific address-line-based "Bank Select" logic disclosed in the '305 Patent's specification.