PTAB

IPR2018-01740

Sony Corporation v. FUJIFILM Corporation

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1. Case Identification

2. Patent Overview

  • Title: Magnetic Recording Medium
  • Brief Description: The ’256 patent relates to a particulate magnetic recording tape with a specific multi-layer structure. The invention aims to provide a thin magnetic tape (less than 8 µm) with improved durability and dimensional stability by controlling the size and number of inorganic filler particles in the nonmagnetic support layer and the coercivity of the magnetic layer.

3. Grounds for Unpatentability

Ground 1: Obviousness over Inaba-283 - Claims 1-6 are obvious over Inaba-283 under 35 U.S.C. §103.

  • Prior Art Relied Upon: Inaba-283 (Patent 5,804,283).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Inaba-283 expressly discloses every limitation of claim 1 except for the specific numerical ranges for the size and cross-sectional number of inorganic filler particles in the nonmagnetic support. Inaba-283 allegedly teaches the conventional four-layer structure (upper magnetic layer, lower layer, nonmagnetic support, backcoat), the overall thickness of less than 8 µm, and the exact claimed coercivity range of 159-239 kA/m. While Inaba-283 teaches incorporating inorganic filler particles into the support, it only describes their effect on surface roughness qualitatively.
    • Motivation to Combine (for §103 grounds): This ground is based on a single reference. The core argument is that the missing particle limitations would have been obvious to a person of ordinary skill in the art (POSA). Petitioner contended that the size and number of filler particles were well-known result-effective variables used to control tape performance. Since Inaba-283 teaches the general concept but not specific values, a POSA would have performed routine optimization to arrive at the claimed ranges to achieve desired tape characteristics.
    • Expectation of Success (for §103 grounds): A POSA would have had a high expectation of success in optimizing filler particle size and number, as this was a common and well-understood practice in the art for controlling tape surface roughness and handling properties.
    • Key Aspects: Petitioner asserted that the ’256 patent fails to demonstrate any criticality or unexpected results associated with the claimed particle ranges, which is necessary to overcome a prima facie case of obviousness for optimizing a result-effective variable.

Ground 2: Obviousness over Inaba-283 and Honda - Claims 1-5 are obvious over Inaba-283 in view of Honda.

  • Prior Art Relied Upon: Inaba-283 (Patent 5,804,283) and Honda (Japanese Application # H6-150286).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground builds on Ground 1, asserting that Honda supplies the specific filler particle limitations missing from Inaba-283. Honda allegedly discloses a two-layer nonmagnetic support with specific filler particle sizes (e.g., 90 nm and 150-450 nm) and areal densities (e.g., 20,000 units/mm²) that fall within or make obvious the claimed ranges for mean particle diameter (40-200 nm) and cross-sectional number (10-200 particles/100 µm²). The combination of Inaba-283's tape structure and Honda's particle specifications allegedly meets all limitations of claims 1-5.
    • Motivation to Combine (for §103 grounds): A POSA would combine these references because both concern magnetic tapes with two-layer substrates designed to have different roughness on each side. As Inaba-283 teaches controlling surface roughness via filler size and amount but provides no specific values, a POSA would have looked to a reference like Honda, which teaches specific, successful particle parameters for a similar substrate, to implement Inaba-283's design.
    • Expectation of Success (for §103 grounds): Success was expected because applying Honda's known substrate filler technology to Inaba-283's particulate tape structure was a combination of known elements to achieve a predictable result.

Ground 3: Obviousness over Inaba-244, Nagasawa, and Masaki - Claims 1-6 are obvious over Inaba-244 in view of Nagasawa and Masaki.

  • Prior Art Relied Upon: Inaba-244 (Japanese Application # 2000-30244), Nagasawa (European Application # EP 1022106), and Masaki (Patent 5,698,311).
  • Core Argument for this Ground:
    • Prior Art Mapping: Inaba-244, which shares inventors with the ’256 patent, allegedly discloses a nearly identical four-layer aramid-based tape meeting the thickness limitation, but does not explicitly describe adding filler particles to the substrate. Nagasawa teaches improving the handling of similar aramid substrates by adding colloidal silica particles of a specific size (80 nm) and amount (0.035 wt%)—a formulation Petitioner argued is identical to an example in the ’256 patent. Masaki teaches that a magnetic layer coercivity of 159-239 kA/m is desirable, supplying the final limitation.
    • Motivation to Combine (for §103 grounds): A POSA starting with Inaba-244's high-performance aramid tape would have been motivated to add filler particles as taught by Nagasawa to improve lubricity and prevent blocking, which were known problems. The substrate manufacturing processes in Inaba-244 and Nagasawa were argued to be virtually identical, making the combination straightforward. The POSA would then have been motivated to select a coercivity in the range taught by Masaki to ensure sufficient output and compatibility with existing recording heads.
    • Expectation of Success (for §103 grounds): A POSA would have reasonably expected success because the combination involved applying a known solution (Nagasawa's fillers) to a known problem (handling of aramid films like Inaba-244's) and using a standard, desirable coercivity range (Masaki's).

4. Key Claim Construction Positions

  • "mean primary particle diameter" (Claims 1-6): Petitioner asserted this term should be construed as the number-weighted mean of the diameters of non-aggregated particles in the nonmagnetic support. This construction is relevant to how the particle sizes disclosed in the prior art are mapped to the claims.
  • "number of particles of said inorganic particles in the cross-section of said nonmagnetic support" (Claims 1-6): Petitioner argued that for a dual-layer substrate, this term refers to the mean number of particles taken across both layers. This construction is critical for the argument in Ground 2, where Honda's areal densities for two separate layers are combined and averaged to meet the claimed cross-sectional particle number limitation.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-6 of Patent 6,630,256 as unpatentable.