PTAB

IPR2017-00625

Sony Corporation v. FUJIFILM Corporation

Patent #: 6,641,891
Filed: January 7, 2017
Petitioner(s): Sony Corporation, Sony Corporation of America, and Sony Electronics Inc.
Patent Owner(s): FUJIFILM CORPORATION
Challenged Claims: 1, 4-9, 11, and 14

Title: Magnetic Recording Medium
Brief Description: The ’891 patent is directed to a magnetic recording medium, such as a tape or disc, with specific physical characteristics intended for high-density and reliable data storage. The disclosed invention centers on improving noise characteristics by controlling the average size of magnetic clusters on the medium's surface within a specific range.

Prior Art Relied Upon: Yamazaki (Patent 6,017,605).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Yamazaki, which shares a common patent owner and inventor with the ’891 patent, explicitly discloses every limitation of the challenged claims except for the specific numeric range for "average magnetic cluster size." Petitioner contended this final limitation is inherently disclosed. The inherency argument was based on the fact that Yamazaki and the ’891 patent describe making magnetic media (tapes T1/T2 in Yamazaki, tape E8 in the ’891 patent) using identical materials, coating compositions, and manufacturing processes. The only significant difference is the milling time: Yamazaki discloses 4-hour and 6-hour milling times, while the ’891 patent’s corresponding example uses a 5-hour time. Because the Yamazaki tapes exhibit "good" noise characteristics (C/N ratio)—a property directly linked to cluster size—Petitioner asserted they must necessarily and inherently possess a cluster size that falls within the ’891 patent’s claimed "good" range.

Prior Art Relied Upon: Yamazaki (Patent 6,017,605).
Core Argument for this Ground:
- Prior Art Mapping: As an alternative to anticipation, Petitioner argued that if Yamazaki does not inherently disclose the claimed cluster size, it would have been obvious for a person of ordinary skill in the art (POSA) to modify Yamazaki’s process to arrive at the claimed invention. Yamazaki teaches all other limitations for producing high-quality magnetic media.
- Motivation to Combine: A POSA would have been motivated to modify Yamazaki's disclosed process. By teaching that desirable media can be produced with milling times of 4 and 6 hours, Yamazaki suggests a workable range for this parameter. A POSA would have been motivated to select a milling time within that range, such as 5 hours, as a matter of routine optimization or simple design choice to fine-tune the known relationship between milling time, cluster size, and media noise.
- Expectation of Success: A POSA would have had a high expectation of success. Since good results were achieved at both 4 and 6 hours of milling, it would be predictable that an intermediate time of 5 hours would also yield a successful medium with desirable noise characteristics. The average cluster size was a known result-effective variable, making its optimization a predictable endeavor.

Prior Art Relied Upon: Yamazaki (Patent 6,017,605), McCann (a 1999 journal article), and Takahashi (a 1998 journal article).
Core Argument for this Ground:
- Prior Art Mapping: This ground was presented as an alternative to Ground 2, asserting the same fundamental obviousness rationale. The core argument remained that it would have been obvious to modify Yamazaki’s process by selecting a 5-hour milling time.
- Motivation to Combine: The motivation to modify Yamazaki was identical to Ground 2. The secondary references, McCann and Takahashi, were introduced to explicitly substantiate the knowledge of a POSA. Petitioner argued these references confirm that the relationships between milling time, the breakup of particle agglomerates (i.e., cluster size), and resulting media noise were well-understood technical principles, reinforcing the motivation to optimize this known variable.
- Expectation of Success: The expectation of success was the same as in Ground 2, with McCann and Takahashi providing explicit, published evidence that the outcome of adjusting milling time was predictable and within the skill of a POSA.

"an average size of magnetic cluster at DC erase" (Claim 1): Petitioner contended this was the most critical term for the invalidity analysis. Petitioner noted that in a related ITC investigation, this term was challenged for indefiniteness due to multiple possible measurement techniques. For the purposes of this IPR, Petitioner argued that under the Broadest Reasonable Interpretation (BRI) standard, the Board should construe the term to be met if a medium has the claimed average cluster size when measured using the specific technique described in the ’891 patent’s specification. Petitioner asserted this construction was sufficient to resolve the controversy for all grounds presented.

Petitioner requests institution of an IPR and cancellation of claims 1, 4-9, 11, and 14 of Patent 6,641,891 as unpatentable.