Coretronic Corp v. Maxell Ltd

1. Case Identification

• Case #: IPR2025-00475
• Patent #: 9,322,530
• Filed: February 7, 2025
• Petitioner(s): Cortronic Corporation and Optoma Coporation
• Patent Owner(s): Maxell, Ltd.
• Challenged Claims: 1, 3, 4, 7, and 9

2. Patent Overview

• Title: Light Source Device
• Brief Description: The ’530 patent discloses a light source device for use in projectors. The device uses a plurality of excitation light sources, a phosphor that converts excitation light to fluorescent light, and optical components arranged such that the excitation light asymmetrically enters a condensing lens to prevent unconverted light from reflecting back into the light sources, thereby improving output and device lifespan.

3. Grounds for Unpatentability

Ground 1: Claims 1, 4, and 7 are anticipated by and/or obvious over Hirata.

• Prior Art Relied Upon: Hirata (Application # 2011/0187999).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hirata discloses every element of the challenged claims. Hirata teaches a projection display apparatus with a light source device comprising a plurality of blue excitation light sources (Fig. 1B), a yellow phosphor that emits fluorescent light upon excitation, a dichroic mirror that transmits the excitation light and reflects the fluorescent light, and a condensing lens. Crucially, Petitioner asserted that Hirata’s Figure 1B shows the two light sources are offset and tilted, causing their emitted light to enter the condensing lens asymmetrically and strike the phosphor at an oblique, non-zero angle (θ≠0), thus satisfying the key limitations of independent claims 1 and 7. Hirata also explicitly discloses that the light sources can be solid light-emitting elements, anticipating dependent claim 4.
  • Key Aspects: To the extent Hirata does not explicitly disclose the asymmetric arrangement, Petitioner contended it would have been an obvious modification for a POSITA to offset the light sources to avoid back reflections, a known issue in the art.

Ground 2: Claims 1, 3, 4, 7, and 9 are obvious over Kurosaki in view of Alpay.

• Prior Art Relied Upon: Kurosaki (Application # 2011/0234998) and Alpay (Application # 2009/0308852).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Kurosaki discloses a base projection system containing nearly all elements of the challenged claims, including a projector with a light source unit having two blue laser excitation sources, a luminescent plate (phosphor), a dichroic mirror, and a condensing lens. While Kurosaki shows the light sources offset from the optical axis, Petitioner relied on Alpay to provide the explicit reasoning and methodology for the claimed asymmetric arrangement. Alpay teaches systems for reducing damaging back-reflections in laser systems by arranging the incident laser beam to asymmetrically enter a focusing lens. This ensures the reflected beam path is angularly separated from the incident beam path, preventing feedback. Petitioner argued this combination renders the limitations of claims 1, 4, 7, and 9 obvious. For claim 3, Petitioner argued a POSITA implementing Alpay's teachings would naturally create an arrangement where the specific angular relationships recited in the claim are not met, thereby satisfying the claim's negative limitation.
  • Motivation to Combine: A POSITA would combine Kurosaki and Alpay to improve the reliability and prevent damage to the laser diodes in Kurosaki's projector. Back-reflection was a well-known problem for lasers, and Alpay provided an effective, non-bulky solution by teaching an asymmetric optical arrangement.
  • Expectation of Success: The combination involved applying known optical principles (preventing back-reflections) to a known system (a laser projector), leading to the predictable result of improved laser stability and longevity.

Ground 3: Claims 1, 3, 4, and 9 are obvious over Huang in view of Alpay.

• Prior Art Relied Upon: Huang (Patent 8,783,886) and Alpay (Application # 2009/0308852).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted a similar rationale as in Ground 2, with Huang serving as the primary reference. Huang discloses an illumination system with a plurality of laser light sources, a wavelength transformer (phosphor), a dichroic mirror, and a condensing lens system. Huang's figures depict an asymmetric arrangement where light sources are offset from the optical axis. However, Petitioner argued that Huang does not explicitly state the purpose is to prevent back-reflections. Alpay was again introduced as teaching the benefits of such an asymmetric arrangement specifically to prevent damaging optical feedback. The combination of Huang’s system with Alpay’s explicit teaching would have rendered the claims obvious.
  • Motivation to Combine: Even though Huang shows an offset arrangement, a POSITA would have looked to Alpay to understand, confirm, and optimize the design to ensure that unconverted excitation light would not return to any of the light sources. The motivation was to enhance the known system of Huang for the known purpose of improving reliability.
  • Expectation of Success: A POSITA would have had a high expectation of success in applying Alpay’s principles to Huang’s system, as it involved modifying an existing optical layout with a known technique to achieve a predictable improvement.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations of Kurosaki with Abu-Ageel and Huang with Abu-Ageel and/or Akiyama, all of which relied on similar theories of combining a base projector system with prior art teaching methods to prevent back-reflections.

4. Arguments Regarding Discretionary Denial

• Petitioner argued against discretionary denial under §314(a) based on the Fintiv factors, asserting that the factors weigh in favor of institution. Petitioner contended that the parallel district court litigation is in its early stages with minimal investment from the court or parties (Fintiv factor 3). While the trial date (March 2026) is near the FWD deadline (July 2026), Petitioner noted that such dates are often uncertain (Fintiv factor 2). Petitioner further stipulated that it would not pursue the IPR grounds in the district court case if the IPR is instituted, eliminating concerns of overlap (Fintiv factor 4). Finally, Petitioner argued the strong merits of the petition weigh heavily in favor of institution (Fintiv factor 6).

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1, 3, 4, 7, and 9 of the ’530 patent as unpatentable.