Coretronic Corp v. Maxell Ltd

1. Case Identification

• Case #: IPR2025-00476
• Patent #: 9,547,226
• Filed: January 17, 2025
• Petitioner(s): Coretronic Corporation and Optoma Corporation
• Patent Owner(s): Maxell, Ltd.
• Challenged Claims: 8, 10, and 12

2. Patent Overview

• Title: Projection-Type Image Display Device
• Brief Description: The ’226 patent discloses a projection-type image display device featuring a light source that uses an excitation light to stimulate a fluorescent material. The invention focuses on the specific arrangement and curvature of an "optical member," comprising convex and concave lenses, to direct the excitation light onto the fluorescent material.

3. Grounds for Unpatentability

Ground 1: Claims 8, 10, and 12 are anticipated by, or obvious over, Kurosaki.

• Prior Art Relied Upon: Kurosaki (Patent 8,721,087).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Kurosaki, which describes a projector with a phosphor-based light source, discloses every element of independent claim 8 and dependent claims 10 and 12. Kurosaki’s projector includes an excitation light source (71), a fluorescent material (phosphor layer 104 on wheel 101), and an optical member for directing the excitation light. Critically, Petitioner asserted that Kurosaki’s condenser lens (78) and concave lens (76) meet the claim limitation of an optical member having a convex lens and a concave lens disposed in that specific order between the excitation source and a dichroic mirror (141). For dependent claim 12, Petitioner contended Kurosaki teaches shaping the excitation light beams to have a uniform, rectangular illumination intensity that is analogous to the shape of the display element (DMD 51).
  • Key Aspects: This ground asserted that Kurosaki is a single reference that contains all the limitations of the challenged claims, including the specific ordering of the convex and concave lenses that the Patent Owner relied upon for patentability during prosecution.

Ground 2: Claims 8 and 10 are anticipated by, or obvious over, Miyamae.

• Prior Art Relied Upon: Miyamae (Japanese Patent Publication No. 2012-199075).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Miyamae, which also describes a projector with a fluorescent light source, discloses all limitations of claims 8 and 10. Miyamae’s system includes an excitation light source (10A), a fluorescent layer (52), a dichroic mirror (30), and various optical elements (collimating optics 20, pickup optics 40) for directing the light. Petitioner mapped these components to the corresponding elements of claim 8. For dependent claim 10, Petitioner argued that Miyamae’s condensing lenses cause the excitation light to be incident on the fluorescent material as a light-condensing position, satisfying the claim’s functional requirement.

Ground 3: Claims 8, 10, and 12 are obvious over Kitano in view of Kurosaki.

• Prior Art Relied Upon: Kitano (Application # 2013/0088471) and Kurosaki (Patent 8,721,087).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Kitano discloses a base projector system with a phosphor-based light source, including an excitation source (laser 304), a fluorescent material (phosphor 302), a dichroic mirror (310), and condensing lenses (311, 312). Petitioner argued that while Kitano teaches the general architecture, Kurosaki supplies the specific "optical member" configuration recited in claim limitation [8.12]: a convex lens followed by a concave lens. Combining Kurosaki's lens arrangement with Kitano's projector would result in the claimed invention.
  • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine Kitano and Kurosaki because both address the same field of projection display devices. A POSITA would have recognized that Kurosaki's specific lens configuration was an available design choice to incorporate into a system like Kitano's to achieve predictable optical results and known advantages.
  • Expectation of Success: The combination was presented as a simple substitution of a known optical subsystem (Kurosaki's lenses) into a compatible system (Kitano's projector), leading to a high expectation of success.

• Additional Grounds: Petitioner asserted that claim 12 is obvious over Miyamae in view of Kurosaki, relying on a similar substitution rationale where Kurosaki's luminance distribution teachings are applied to Miyamae's base system.

4. Key Claim Construction Positions

• Petitioner argued that the terms “a light-condensing position” and “an emission side of the excitation light relative to the fluorescent material” in claim 8 are ambiguous. However, for the purpose of the petition, Petitioner proposed that the most reasonable interpretation of “a light-condensing position” is an illumination region formed by converging light rays, and the “emission side” is the surface of the fluorescent material facing the excitation light source. This interpretation was central to mapping the prior art to these limitations.

5. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under §325(d) because the primary references (Kurosaki and Miyamae) were not considered during the original prosecution, and the petition presents new arguments and evidence, including an expert declaration.
• Petitioner also argued against discretionary denial under Fintiv factors, asserting that:
  • The co-pending district court litigation is in a very early stage, with a trial date nearly two years away and subject to change.
  • The merits of the petition are exceptionally strong.
  • Petitioner has been diligent in filing the petition and stipulated that, if instituted, it will not pursue the same grounds in the district court.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 8, 10, and 12 of the ’226 patent as unpatentable.