Hisense USA Corp v. Brightplus Ventures LLC

1. Case Identification

• Case #: IPR2023-01401
• Patent #: 8,941,331
• Filed: September 14, 2023
• Petitioner(s): Hisense USA Corporation
• Patent Owner(s): Brightplus Ventures LLC
• Challenged Claims: 17-18 and 20-25

2. Patent Overview

• Title: Solid-State Lighting Panels with Variable Voltage Boost Current Sources
• Brief Description: The ’331 patent relates to a lighting system including at least first and second strings of solid-state lighting devices, corresponding current supply circuits, and a pulse width modulation (PWM) controller coupled to the current supply circuits to provide independent current control.

3. Grounds for Unpatentability

Ground 1: Obviousness over Lys and Grootes - Claim 17 is obvious over Lys in view of Grootes.

• Prior Art Relied Upon: Lys (WO 2005/089293) and Grootes (Application # 2007/0046485).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Lys, the primary reference, disclosed a lighting system with multiple strings of LEDs and a PWM controller to vary color and intensity. However, to the extent Lys did not explicitly teach a separate current supply circuit for each string, Grootes supplied this limitation. Grootes taught an LED backlight structure where each string of LEDs (e.g., red, green, blue) was connected to its own individually controllable current source.
  • Motivation to Combine: A POSITA would combine Grootes's individual current source design with Lys's lighting system to achieve a predictable improvement. Both references were in the same field and addressed the common challenge of improving color and brightness uniformity in LED systems. Grootes explicitly taught that using separate current sources allows for better control over the brightness of each associated LED string to achieve a desired white point, a known technique to improve systems like the one in Lys.
  • Expectation of Success: Because both references used well-known components for the common goal of controlling LED lighting, a POSITA would have had a high expectation of success in integrating Grootes's per-string current sources into Lys's system.

Ground 2: Obviousness over Lys, Grootes, and Xu - Claims 18-20 and 22-25 are obvious over Lys, Grootes, and Xu.

• Prior Art Relied Upon: Lys (WO 2005/089293), Grootes (Application # 2007/0046485), and Xu (CN 1588523).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground built upon the Lys/Grootes combination by adding Xu to teach limitations in dependent claims 18-20. Petitioner asserted Xu disclosed a constant current supply circuit configured to operate in continuous current mode, including various converter types such as a boost converter (claim 18). Xu also taught using a sense resistor in a feedback circuit to provide a feedback signal for closed-loop control to achieve a constant color temperature (claims 19-20). For claims 22-25, Petitioner argued Lys alone taught the use of wavelength conversion phosphors and various color combinations (blue/yellow and red) as well as the independent control of multiple strings.
  • Motivation to Combine: A POSITA would have been motivated to incorporate Xu’s teachings into the Lys/Grootes system to provide a constant turn-on current and achieve a constant color temperature, thereby further improving the light quality and uniformity. Xu addressed the known problem of slow capacitor charging/discharging in LED circuits, providing a well-understood solution (a constant current supply with a sense resistor) that was directly applicable to the combined Lys/Grootes system.
  • Expectation of Success: The combination involved applying well-known electronic techniques (boost converters, feedback loops) from Xu to the known LED driver architecture of Lys/Grootes, leading to a high expectation of success.

Ground 3: Obviousness over Mueller and Grootes - Claim 17 is obvious over Mueller in view of Grootes.

• Prior Art Relied Upon: Mueller (Application # 2005/0047134) and Grootes (Application # 2007/0046485).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground presented an alternative to Ground 1, using Mueller as the base reference. Petitioner argued Mueller disclosed a networked lighting system with multiple LED units arranged in strings, controlled by lighting unit controllers using PWM signals. As in Ground 1, Grootes was cited for its clear teaching of connecting each LED string to its own current source for independent brightness control.
  • Motivation to Combine: The motivation was parallel to that in Ground 1. A POSITA would have been motivated to modify Mueller’s system by incorporating the individual current sources from Grootes. Both references aimed to solve the same problems of color and brightness uniformity. Applying Grootes’s more specific control method to Mueller's general lighting system was presented as a combination of known elements for a predictable result.
  • Expectation of Success: A POSITA would have reasonably expected success in combining the references, as it involved incorporating a known control component (Grootes's current source) into a standard LED lighting architecture (Mueller's system).

• Additional Grounds: Petitioner asserted additional obviousness challenges for claim 21 over Lys/Grootes/Xu in view of Blum (Patent 5,663,667) for adding a filter to the feedback input (Ground 3); for claims 18 and 20 over Mueller/Grootes in view of Xu (Ground 5); and for claim 21 over Mueller/Grootes/Xu in view of Blum (Ground 6). These grounds relied on similar design modification theories to add known circuit elements for their predictable functions.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §314(a) based on Fintiv factors would be inappropriate. The parallel district court litigation was in its early stages, with infringement contentions having been served recently and no trial date scheduled. Petitioner asserted that minimal investment had been made by the parties in the litigation, and a decision from the Board would simplify issues.
• Petitioner also argued that denial under 35 U.S.C. §325(d) was inappropriate because none of the prior art references relied upon in the petition were previously presented to or considered by the USPTO during the prosecution of the ’331 patent.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 17-18 and 20-25 of the ’331 patent as unpatentable.