Coretronic Corp v. Maxell Ltd

1. Case Identification

• Case #: IPR2025-00474
• Patent #: 8,593,580
• Filed: January 29, 2025
• Petitioner(s): Coretronic Corporation and Optoma Corporation
• Patent Owner(s): Maxell, Ltd.
• Challenged Claims: 1, 3-11, 17, 18, and 32-38

2. Patent Overview

• Title: Projection-Type Display Apparatus
• Brief Description: The ’580 patent describes a projection-type display apparatus that uses a solid-state light source, such as an LED or laser diode, to generate white light. The apparatus excites a fluorescent substance with light from the solid-state element and then separates this white light into component colors for modulation and projection.

3. Grounds for Unpatentability

Ground 1: Obviousness over Ishino and Erchak

Claims 1, 3-5, 8-9, 32-35, and 38 are obvious over Ishino in view of Erchak.

• Prior Art Relied Upon: Ishino (Application # 2003/0189693) and Erchak (Patent 7,196,354).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Ishino discloses a complete projection-type display apparatus with all the core optical components claimed, including a light source, a light separation system, light modulation means (liquid crystal panels), and a projection lens. However, Ishino’s light source is a conventional lamp (e.g., mercury lamp). Erchak discloses a solid-state light source that generates white light by using an LED to excite a phosphor material, which is precisely the type of light source claimed in the ’580 patent. Erchak further teaches that the fluorescent substance can have a patterned surface with concave portions to improve light extraction, meeting the final limitation of independent claims 1 and 32.
  • Motivation to Combine: Petitioner asserted that a person of ordinary skill in the art (POSITA) would have been motivated to replace Ishino’s conventional lamp with Erchak’s more reliable and efficient solid-state light source. The ’580 patent itself acknowledged the known drawbacks of discharge lamps (short lifetime, high voltage) and the trend toward using solid-state sources in projectors. This replacement was presented as a predictable substitution of one known light source for another to achieve known benefits.
  • Expectation of Success: A POSITA would have had a reasonable expectation of success in this combination, as it involved integrating a known, improved component (Erchak's light source) into a standard projector architecture (Ishino's system) without changing the fundamental principles of operation.

Ground 2: Obviousness over Uchiyama and Erchak

Claims 1, 3-5, 8-9, 32-35, and 38 are obvious over Uchiyama in view of Erchak.

• Prior Art Relied Upon: Uchiyama (Application # 2006/0203202) and Erchak (Patent 7,196,354).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground presented an alternative to Ground 1, using Uchiyama as the primary reference. Petitioner argued that Uchiyama, like Ishino, discloses a conventional projection display apparatus with a lamp-based light source and all the necessary optical components for separating light, modulating it with liquid crystal light valves, and projecting an image. The argument then followed the same logic as Ground 1: Erchak supplies the claimed solid-state light source with a patterned fluorescent substance.
  • Motivation to Combine: The motivation was identical to that in Ground 1. A POSITA would have sought to upgrade Uchiyama’s lamp-based projector with the known advantages of Erchak’s solid-state light-emitting device technology.
  • Expectation of Success: Petitioner contended the combination would yield predictable and operable results for the same reasons articulated in the Ishino-based ground.

Ground 3: Obviousness over Ishino and Li ’415

Claims 10 and 18 are obvious over Ishino in view of Li ’415.

• Prior Art Relied Upon: Ishino (Application # 2003/0189693) and Li ’415 (Chinese Publication # 101498415).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground specifically targeted claim 10, which adds the limitation of a "separation mirror" disposed between the solid-state element and the fluorescent substance. Petitioner argued that while Ishino provides the base projector, Li ’415 discloses a solid-state light source that explicitly uses a dichroic filter (construed as the claimed "separation mirror") positioned between the excitation light source and the fluorescent material. This dichroic filter is configured to pass the excitation light and reflect the light from the fluorescent substance, directly teaching the structure and function required by claim 10.
  • Motivation to Combine: A POSITA looking to implement a solid-state light source in Ishino's projector would have looked to known configurations like that in Li ’415. Li ’415’s use of a dichroic filter was a known technique for managing light paths in such sources.
  • Expectation of Success: The combination was asserted to be a straightforward application of known optical design principles with a high expectation of success.
• Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations including Ishino, Uchiyama, Li ’415, Erchak, and Bakker (Application # 2007/0182932). These grounds relied on similar component-swapping or design modification theories, with Li ’415 and Erchak providing alternative solid-state light sources and Bakker teaching specific properties of dichroic mirrors for polarization control relevant to dependent claims.

4. Key Claim Construction Positions

• "separation mirror" (claim 10): Petitioner argued this is a means-plus-function term lacking sufficient corresponding structure in the specification. For the purpose of the IPR, Petitioner proposed construing it to encompass the structure of a dichroic mirror, as disclosed in prior art like Li ’415.
• "light modulation means" (claim 1): Petitioner asserted this is a means-plus-function term whose corresponding structure is a set of three panels (e.g., transmission-type liquid crystal panels), one for each separated color light.
• "emitting light" (claim 3): Petitioner noted this term is ambiguous, as claim 1 refers to excitation light, white light, and fluorescent light. For the petition, the term was interpreted as the light emitting from the fluorescent material.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under §325(d) or §314(a) is not warranted. The petition asserted that the cited prior art combinations were not considered by the examiner during prosecution. Regarding the Fintiv factors for co-pending litigation, Petitioner argued for institution because: (1) the district court case is in a very early stage with minimal investment by the parties or the court; (2) the Board’s Final Written Decision would issue before the scheduled trial date; and (3) Petitioner stipulated that it would not pursue the same grounds in district court if the IPR is instituted, thereby avoiding duplicative efforts.

6. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1, 3-11, 17, 18, and 32-38 of the ’580 patent as unpatentable.