PTAB

IPR2020-00750

Satco Products Inc v. Seoul Viosys Co Ltd

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Light Emitting Device
  • Brief Description: The ’946 patent discloses a light-emitting device for AC power operation, which has an array of light-emitting cells connected in series. The technology aims to address issues like flicker that can occur when driving LEDs with an AC power source.

3. Grounds for Unpatentability

Ground 1: Obviousness over Hochstein, Krames, and Rossner - Claims 1, 3-4 are obvious over Hochstein in view of Krames and Rossner.

  • Prior Art Relied Upon: Hochstein (Patent 5,661,645), Krames (an October 1999 article in Applied Physics Letters), and Rossner (WO 2004/082032).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Hochstein disclosed a power supply apparatus for an LED array using a pulse-width modulation (PWM) module, which provides a periodically changing input voltage. However, Hochstein did not detail the LED chip design or flicker mitigation techniques. Krames taught that shaping LED chips with inclined sidewalls using a truncated-inverted-pyramid (TIP) geometry was a well-known method to improve light extraction efficiency. Rossner taught using "storage" or "delay" phosphors with a PWM-driven LED to maintain light emission during the "off" cycles. Petitioner asserted that the combination meets the key limitations of claim 1: Hochstein provided the PWM-driven array, Krames provided the "inclined side surface," and Rossner's storage phosphors ensured that the luminous intensity would periodically change but remain above zero during the off-cycle, thus meeting the "second peak value and a minimum value" limitation where the minimum is greater than zero. For dependent claims, Petitioner argued Hochstein's inclusion of a full-wave bridge rectifier met claim 3, and its disclosure of five LED array strings met claim 4.
    • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Hochstein with Krames to incorporate the known benefits of improved light extraction into Hochstein's basic LED array. A POSITA would further add Rossner's storage phosphors to Hochstein's PWM-driven device to improve flicker performance and enable a wider range of control, such as deep dimming, which were known benefits of using storage phosphors with low duty cycles.
    • Expectation of Success: A POSITA would have a high expectation of success, as implementing inclined sidewalls per Krames was a known manufacturing process (e.g., using a beveled dicing blade), and applying phosphors to LEDs per Rossner was a conventional technique (e.g., mixing phosphor powder in an epoxy resin and depositing it on the chip).

Ground 2: Obviousness over Masatoshi, Krames, and Rossner - Claims 1, 3-4 are obvious over Masatoshi in view of Krames and Rossner.

  • Prior Art Relied Upon: Masatoshi (Japanese Application # H5-198843), Krames (an October 1999 article in Applied Physics Letters), and Rossner (WO 2004/082032).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner contended that Masatoshi disclosed a light-emitting device with a series-connected LED array driven by an AC input via a bridge rectifier, where the rectifier itself was composed of LEDs. The rectified voltage from this circuit is periodic and has peak values followed by values that do not turn on the LEDs, meeting some limitations of claim 1. As with the Hochstein-based ground, Petitioner argued Krames taught the "inclined side surface" limitation, and Rossner taught using storage phosphors to reduce flicker. The phosphors would absorb light when the LEDs in Masatoshi's circuit were on and continue emitting light when they were off, resulting in a periodically changing luminous intensity with a non-zero minimum value. Dependent claims 3 and 4 were met because Masatoshi's primary circuit is a bridge rectifier, and adding a second array would be a simple duplication of parts for increased brightness.
    • Motivation to Combine: A POSITA would be motivated to improve Masatoshi's basic AC-driven LED circuit. The motivation to add Krames's TIP geometry was to enhance the light extraction efficiency of Masatoshi's LEDs, a known and desirable improvement. A POSITA would combine this with Rossner's storage phosphors to address the inherent flicker from Masatoshi's rectified AC driver, a known problem that phosphors were known to mitigate.
    • Expectation of Success: The combination was predictable. Both adding inclined sidewalls and applying phosphors were conventional, well-understood techniques in the field of LED design and manufacturing, ensuring a high likelihood of success.

  • Additional Grounds: Petitioner asserted that claim 8 is obvious over Masatoshi in view of Rossner. This argument is similar to Ground 2 but omits Krames, as claim 8 does not require inclined sidewalls. Petitioner also asserted that claim 8 is obvious over Jiang-941 (Application # 2004/0080941) in view of the general knowledge to use phosphors to create white light from blue LEDs for general lighting applications.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1, 3, 4, and 8 of the ’946 patent as unpatentable.