PTAB

IPR2025-00941

Coretronic Corp v. Maxell Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Projection Optical Unit
  • Brief Description: The ’988 patent describes a projection optical unit designed to project an enlarged image from a display element onto a screen. The system employs a two-stage magnification process: a first projection optical unit creates an initial enlarged image with magnification M1, and a second projection optical unit further enlarges this intermediate image onto the final screen with magnification M2, where the patent claims M2 is greater than M1.

3. Grounds for Unpatentability

Ground 1: Claims 1 and 7 are anticipated by or obvious over Konno

  • Prior Art Relied Upon: Konno (Patent 5,357,289).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Konno’s projector lens system discloses every element of claims 1 and 7. Konno’s “first lens group 14” was identified as the claimed “first projection optical unit,” and its “third lens group 16” was mapped to the “second projection optical unit.” Petitioner asserted that Konno teaches forming an intermediate optical image on its "second lens group 15," which is then projected as a magnified picture onto a screen. Konno explicitly states its first lens group provides a magnification (M1) of "×2," and Petitioner argued the final projected image is inherently larger, making magnification M2 greater than M1. The claim limitation of an "aperture stop" was allegedly met by Konno’s disclosure of an “iris 14a” for controlling light quantity.
    • Motivation to Combine (for §103 grounds): Alternatively, Petitioner contended that even if Konno does not explicitly teach M2 > M1, it would be obvious to a POSITA that the purpose of Konno's third lens group was to further magnify the intermediate image for projection, making this an obvious design choice.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success as the system operated according to well-understood optical principles.

Ground 2: Claims 1 and 7 are obvious over Sato in view of Dorval and Takamoto

  • Prior Art Relied Upon: Sato (Patent 5,302,983), Dorval (Application # 2002/0067467), and Takamoto (Patent 6,028,715).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Sato’s projecting apparatus provides the basic two-stage magnification structure with a "first optical system" (auxiliary lens 17) and a "second optical system" (projecting lens 14). To supplement Sato's general disclosure of enlargement, Dorval was cited to explicitly teach a system with a first magnification (M1) of 3.8x and a second magnification (M2) of approximately 5.3x, thereby clearly satisfying the M2>M1 limitation. The final element, an aperture stop, was supplied by Takamoto, which teaches the specific benefits of placing an aperture stop within a lens unit to maintain a constant F-number.
    • Motivation to Combine (for §103 grounds): A POSITA would combine Sato with Dorval to create a compact projection system with high, well-defined magnification, as both references are in the same field. A POSITA would further be motivated to incorporate Takamoto’s aperture stop into the first lens group of the combined system to gain the known benefit of stable illumination control, which was a standard design consideration.
    • Expectation of Success (for §103 grounds): The combination involved applying known optical components for their predictable functions, leading to a high expectation of success.

Ground 3: Claim 8 is obvious over Sato, Dorval, and Takamoto, further in view of Takeuchi

  • Prior Art Relied Upon: Sato (Patent 5,302,983), Dorval (Application # 2002/0067467), Takamoto (Patent 6,028,715), and Takeuchi (Application # 2002/0044263).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built upon the combination asserted against claims 1 and 7, adding Takeuchi to teach the final limitation of dependent claim 8: making the optical-axis center of the projection unit "eccentric with respect to a center of the screen." Takeuchi was cited for its explicit disclosure that creating an eccentric optical axis allows the overall projection system to be made more compact, a significant benefit in rear-projection devices.
    • Motivation to Combine (for §103 grounds): A POSITA seeking to improve the Sato/Dorval/Takamoto combination by reducing its physical size would have been directly motivated to incorporate the space-saving technique taught by Takeuchi. Since all references concern projector optics, it would be a natural and logical modification.
    • Expectation of Success (for §103 grounds): A POSITA would have a reasonable expectation of success in applying Takeuchi's geometric configuration to the combined Sato system, as it was a known method for achieving compactness.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including: claim 8 over Konno and Lundberg; claims 1 and 7 over Ninomiya and Dorval; claim 8 over Ninomiya, Dorval, and Takeuchi; and claims 1, 7, and 8 over Kurematsu, Dorval, and Takamoto. These grounds relied on similar principles of combining primary projector systems with secondary references that taught specific desired features like adjustable optical axes or magnification ratios.

4. Key Claim Construction Positions

  • Petitioner argued that the claim term "the image display element side" is ambiguous because both projection units in the claimed invention form an image. For the petition's analysis, however, Petitioner adopted the Patent Owner's proposed construction from related district court litigation: "a side after the image display element and before the second projection optical unit."

5. Relief Requested

  • Petitioner requests the institution of an inter partes review and the cancellation of claims 1, 7, and 8 of the ’988 patent as unpatentable.