Sony Corp v. Fujifilm Corp

1. Case Identification

• Case #: IPR2017-00625
• Patent #: 6,641,891
• Filed: January 7, 2017
• Petitioner(s): Sony Corporation
• Patent Owner(s): Fujifilm Corporation
• Challenged Claims: 1, 4-9, 11, and 14

2. Patent Overview

• Title: Magnetic Recording Medium
• Brief Description: The ’891 patent discloses a magnetic recording medium, such as a tape or disc, designed for high-density data storage. The invention purports to achieve improved noise characteristics by limiting the average size of magnetic clusters in the magnetic layer to a specific range.

3. Grounds for Unpatentability

Ground 1: Anticipation over Yamazaki - Claims 1, 4-7, 11, and 14 are anticipated by Yamazaki under 35 U.S.C. §102(b).

• Prior Art Relied Upon: Yamazaki (Patent 6,017,605).
• Core Argument for this Ground: Petitioner argued that Yamazaki, which shares a common inventor and assignee with the ’891 patent, explicitly discloses every limitation of the challenged claims except for the "average size of magnetic cluster." Petitioner contended this final limitation is inherently disclosed in Yamazaki’s examples.
  • Prior Art Mapping: Petitioner asserted that Yamazaki discloses a magnetic recording medium with an essentially nonmagnetic lower layer and a magnetic layer comprising ferromagnetic powder in a binder. Yamazaki’s examples (tapes T1/T2 and discs D1/D2) were alleged to use the same materials (e.g., ferromagnetic powder "A") and identical manufacturing processes as the examples in the ’891 patent that fall within the claimed cluster size range. The only significant difference identified was the milling time; Yamazaki’s examples were milled for 4 and 6 hours, bracketing the 5-hour milling time used for the ’891 patent’s primary example (E8). Because Yamazaki’s media achieved the same "good" noise characteristics that the ’891 patent attributes to the claimed cluster size, Petitioner argued that the cluster size must necessarily and inherently fall within the claimed range.

Ground 2: Obviousness over Yamazaki - Claims 1, 4-9, 11, and 14 are obvious over Yamazaki under 35 U.S.C. §103.

• Prior Art Relied Upon: Yamazaki (Patent 6,017,605).

• Core Argument for this Ground: As an alternative to inherency, Petitioner argued that if Yamazaki does not disclose the specific cluster size, a person of ordinary skill in the art (POSITA) would have been motivated to modify Yamazaki’s process to arrive at the claimed invention with a reasonable expectation of success.

  • Prior Art Mapping: Petitioner argued Yamazaki teaches all elements of the claims except for the specific cluster size range. For dependent claims 8 and 9, which recite specific magnetic layer thicknesses, Petitioner noted that Yamazaki teaches a broader, overlapping range of thicknesses (0.01 to 0.25 µm), rendering the claimed narrower ranges prima facie obvious.
  • Motivation to Combine: A POSITA would have been motivated to modify Yamazaki’s disclosed process for several reasons. First, since Yamazaki teaches that milling for 4 and 6 hours produces media with good noise characteristics, it would have been an obvious design choice to test an intermediate milling time, such as 5 hours, to optimize the known trade-off between milling time, cluster size, and noise. Second, the knowledge that milling time was a result-effective variable for controlling cluster size and noise would motivate a POSITA to perform routine optimization to find the ideal parameters for a desired performance level.
  • Expectation of Success: A POSITA would have had a high expectation of success. Yamazaki’s successful examples at 4 and 6 hours of milling created a clear path for optimization. Because the relationship between milling time and noise reduction was well-understood, modifying the milling time to a value between two successful data points would be expected to produce a predictable, successful result.

• Additional Grounds: Petitioner asserted Ground 3, an alternative obviousness challenge for claims 1, 4-9, 11, and 14 over Yamazaki in view of McCann (a 1999 journal article) and Takahashi (a 1998 IEEE transaction). This ground presented the same substantive arguments as Ground 2 but treated McCann and Takahashi, which were used as evidence of background knowledge in Ground 2, as explicit prior art references in the combination.

4. Key Claim Construction Positions

• "an average size of magnetic cluster at DC erase": Petitioner noted that this term was subject to an indefiniteness challenge in a related ITC investigation. For the purposes of the IPR, Petitioner argued that under the Broadest Reasonable Interpretation (BRI) standard, the term should be interpreted broadly to encompass, at a minimum, a recording medium that meets the claimed cluster size when measured using the specific technique described in the ’891 patent’s specification. Petitioner asserted that all grounds demonstrate unpatentability even under this narrow construction, as the prior art examples were made and measured in a directly comparable manner.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1, 4-9, 11, and 14 of Patent 6,641,891 as unpatentable.