Phenix Longhorn LLC v. Phenix Longhorn LLC

1. Case Identification

• Case #: IPR2018-01255
• Patent #: 7,233,305
• Filed: June 19, 2018
• Petitioner(s): Wistron Corporation
• Patent Owner(s): Phenix Longhorn, LLC
• Challenged Claims: 1, 2, 4, 5

2. Patent Overview

• Title: Gamma Reference Voltage Generator
• Brief Description: The ’305 patent is directed to a programmable integrated circuit for generating gamma correction reference voltages for use in LCDs. The invention describes a circuit with a programming interface, a multiplexer, and multiple banks of programmable analog floating gate memory cells to store and output different sets of gamma voltages for dynamic or application-based correction.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, 4, and 5 are obvious over Kang.

• Prior Art Relied Upon: Kang (Application # 2002/0063666).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kang discloses a multi-mode gamma voltage generator that meets all limitations of the challenged claims. Kang’s memory, which can be implemented with EEPROM or EPROM, was asserted to be the claimed "non-volatile storage cells." Its capability to store gamma data for "at least two modes" was argued to teach the "two or more banks" of cells. Petitioner contended that Kang’s "control means" for selecting a mode in response to an "external mode signal" satisfies the limitation for a "means to switch between the banks." Finally, Petitioner asserted that Kang's use of a common I²C serial interface for addressing is an obvious design choice and a functional equivalent to the claimed multiplexer, as both are commodity components that perform identical addressing functions in an integrated circuit.
  • Motivation to Combine: Not applicable.
  • Expectation of Success: Not applicable.

Ground 2: Claims 1, 2, 4, and 5 are obvious over Da Costa.

• Prior Art Relied Upon: Da Costa (Patent 6,100,879).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Da Costa’s smart controller chip for active matrix displays renders the claims obvious. Da Costa teaches an integrated circuit with on-chip flash memory ("non-volatile storage cells") that can store up to ten separate gamma curves, which Petitioner argued satisfies the "two or more banks" limitation. The system includes MUX circuits (e.g., MUX 706) for selecting among different gamma curves based on control signals, which Petitioner equated to the claimed "means to switch." Similar to the argument against Kang, Petitioner asserted that Da Costa’s use of a serial bus for programming the memory is an obvious, interchangeable equivalent to the claimed multiplexer.
  • Motivation to Combine: Not applicable.
  • Expectation of Success: Not applicable.

Ground 5: Claims 1, 2, 4, and 5 are obvious over Da Costa in view of Tsai.

• Prior Art Relied Upon: Da Costa (Patent 6,100,879) and Tsai (Patent 5,974,528).

• Core Argument for this Ground:

  • Prior Art Mapping: This combination ground was presented to explicitly address the multiplexer limitation should the Board find Da Costa alone insufficient. Petitioner argued that Da Costa discloses the primary system: a display controller with integrated flash memory for storing multiple gamma curves. Tsai, which teaches a microcomputer with embedded flash memory, was cited for its explicit disclosure of using a "bus multiplexer" to connect an I/O circuit to a register set for the express purpose of programming data into the memory.
  • Motivation to Combine: A POSA implementing the system of Da Costa, which is silent on the specific components used for programming its flash memory, would be motivated to consult other references to learn how to program it. Petitioner argued a POSA would find Tsai, which provides this missing detail and teaches a well-known method of using a multiplexer to program embedded memory.
  • Expectation of Success: Petitioner asserted that a POSA would have had a high expectation of success, as the combination involves applying a standard programming architecture from Tsai to the known display controller system of Da Costa to achieve the predictable result of a programmable gamma generator.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including grounds based on Petropoulos (Application # 2003/0090580) alone, Tanaka (Application # 2003/0132906) alone, and combinations of Tanaka with Tsai and Petropoulos with Kang, relying on similar arguments and design choice rationales.

4. Key Claim Construction Positions

• The petition argued for a specific construction of the term "non-volatile storage cells" to mean "computer memory that retains its stored data after power is removed..." and to encompass both analog and digital memory types (e.g., EEPROM, Flash EEPROM). This construction was based on the doctrine of claim differentiation; because dependent claim 4 specifically recites that the cells hold analog voltage values, independent claim 1 must be broader. This broad construction is critical to Petitioner's arguments for applying prior art that discloses various digital non-volatile memories.

5. Key Technical Contentions (Beyond Claim Construction)

• A central contention was that the ’305 patent is not entitled to its claimed priority date from the ’680 provisional application. Petitioner argued the provisional application's specification describes an entirely different invention ("Haptic Targeting Device") and its figures alone fail to provide adequate written description for key limitations of the challenged claims, including the gamma reference voltage signals, the organization into multiple banks, and the means for switching. Disqualifying the priority date makes certain references, such as Tanaka, stronger prior art.

6. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) would be inappropriate. The core reason provided was that each ground presented relies on at least one prior art reference that was not before the Examiner during the original prosecution of the ’305 patent, in addition to new, unconsidered expert testimony.

7. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1, 2, 4, and 5 of the ’305 patent as unpatentable.