PTAB

IPR2020-00608

Satco Products Inc v. Seoul Viosys Co Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Light Emitting Diode Chip Having Distributed Bragg Reflector
  • Brief Description: The ’631 patent discloses a light-emitting diode (LED) chip designed to increase light emission efficiency. The technology centers on using a stacked configuration of a first and a second distributed Bragg reflector (DBR) on the backside of a transparent substrate, where each DBR is optimized to reflect a different range of light wavelengths.

3. Grounds for Unpatentability

Ground 1: Obviousness over Zhao and Garbuzov - Claims 1, 5, 13-15 are obvious over Zhao in view of Garbuzov.

  • Prior Art Relied Upon: Zhao (Y.S. Zhao, et al., Efficiency Enhancement of InGaN/GaN Light Emitting Diodes with a Back-Surface Distributed Bragg Reflector, J. Elec. Materials (2003)) and Garbuzov (Patent 6,404,125).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Zhao, a publication describing backside DBR-enhanced InGaN/GaN LEDs, teaches nearly all elements of independent claim 1. Specifically, Zhao disclosed an LED chip with a light-emitting structure on a sapphire substrate and a "double quarter-wave stack" DBR on the backside of the substrate. This double-stack DBR consisted of two separate DBRs, each optimized for a different peak wavelength (470 nm and 520 nm), to create a single, broadband reflector. Petitioner contended that Garbuzov remedied Zhao’s lack of an explicit phosphor element by teaching an LED that uses a phosphor layer to convert a first band of wavelengths (e.g., blue light from the active region) into a second, longer band of wavelengths to produce, for example, white light. Garbuzov also taught using a reflector to redirect both the original and the phosphor-converted light toward the exit facet of the LED. Dependent claims 13-15, which recite specific optical properties of the DBR layers, were allegedly taught by the inherent quarter-wave stack design of Zhao's DBRs.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Zhao's efficient broadband DBR structure with Garbuzov's well-known phosphor-conversion technology. The goal would be to create a high-efficiency white or multi-color LED, a common objective in the field. Petitioner asserted that Zhao’s stated goal of creating a reflector design for "the full range of LEDs being produced" expressly suggested its application to phosphor-converted LEDs like those in Garbuzov. The combination was a predictable integration of known technologies to achieve improved performance.
    • Expectation of Success: A POSITA would have had a high expectation of success because the combination involved applying a standard technique (phosphor conversion from Garbuzov) to a similar device structure (the InGaN/GaN LED of Zhao). The underlying principles were well-understood, and the results of the combination—wavelength conversion with high reflectivity—were predictable.
    • Key Aspects: Petitioner argued that the claimed ordering of the DBRs (the reflector for the longer, phosphor-converted wavelength being closer to the substrate) was a simple design choice. It represented one of only two possible arrangements, and simulations showed that reversing the order had a negligible effect on performance, making the specific claimed arrangement an obvious selection.

Ground 2: Obviousness over Zhao, Garbuzov, and Niu - Claim 7 is obvious over Zhao in view of Garbuzov, and further in view of Niu.

  • Prior Art Relied Upon: Zhao, Garbuzov, and Niu (P. Niu, et al., Enhancing the light extraction efficiency of GaN-based LEDs, Proc. SPIE 6828 (Nov. 2007)).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground incorporated the arguments from Ground 1 and addressed the additional limitation of claim 7, which requires that the "first surface of the substrate comprises a patterned surface." Niu taught that using a patterned sapphire substrate (PSS) was a well-known technique for improving the external quantum efficiency of GaN-based LEDs. The patterning scatters light at the substrate interface, increasing the probability of photons escaping the LED.
    • Motivation to Combine: A POSITA seeking to maximize light extraction would combine the teachings of Zhao and Garbuzov with the PSS taught by Niu. Niu itself suggested combining different methodologies to improve efficiency. Adding a PSS to the base LED design was a known, complementary technique to further enhance performance, a primary goal in LED design.

Ground 3: Obviousness over Zhao, Garbuzov, and Slater, Jr. - Claim 8 is obvious over Zhao in view of Garbuzov, and further in view of Slater, Jr.

  • Prior Art Relied Upon: Zhao, Garbuzov, and Slater, Jr. (Patent 6,791,119).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground incorporated the arguments from Ground 1 and addressed the limitation of claim 8, which requires the substrate area to be "at least 90,000 µm²." Slater, Jr. taught that it was desirable to increase the area of LED chips (e.g., to greater than 0.1 mm², which is 100,000 µm²) to provide larger, brighter LEDs for lighting applications.
    • Motivation to Combine: The motivation was to satisfy the known industry trend and market demand for higher-output LEDs. A POSITA would find it obvious to apply the efficiency-enhancing techniques of Zhao and Garbuzov to the larger substrate sizes taught by Slater, Jr. to produce a brighter, more powerful LED. This was a simple and predictable scaling of a known device.

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under 35 U.S.C. § 325(d) would be inappropriate. It contended that the grounds present novel patentability issues because the primary combination of Zhao and Garbuzov was never considered during prosecution. Although Zhao was listed as a reference on the face of the ’631 patent, it was never applied in any rejection or discussed by the Examiner. Garbuzov was not cited at all.

5. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1, 5, 7, 8, and 13-15 of the ’631 patent as unpatentable.