PTAB

IPR2018-01740

Sony Corp v. Fujifilm Corp

Log In
Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Magnetic Recording Medium
  • Brief Description: The ’256 patent discloses a particulate magnetic recording tape with a four-layer structure (upper magnetic, lower nonmagnetic, nonmagnetic support, backcoat). The invention is directed at improving durability and dimensional stability in thin tapes (< 8 µm) by specifying ranges for the magnetic layer’s coercivity and, crucially, for the size and cross-sectional number of inorganic filler particles within the nonmagnetic support layer.

3. Grounds for Unpatentability

Ground 1: Obviousness over Inaba-283 - Claims 1-6 are obvious over Inaba-283.

  • 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 a magnetic tape with nearly all limitations of claim 1. This includes the conventional four-layer structure, an overall thickness less than 8 µm, and a magnetic layer coercivity that is identical to the claimed range of 159-239 kA/m. Inaba-283 also teaches incorporating inorganic "filler" particles into the nonmagnetic support to control surface roughness. The only limitations not explicitly disclosed are the specific numerical ranges for the mean particle diameter (40-200 nm) and the cross-sectional particle number (10-200/100 µm²).
    • Motivation to Combine (for §103 grounds): This ground is based on a single reference. The motivation to arrive at the claimed particle ranges stemmed from the fact that particle size and number were well-known result-effective variables. Inaba-283 itself taught that these parameters could be varied to control surface roughness. Petitioner contended that determining the optimal ranges for these known variables to achieve desired tape performance would have been a matter of routine optimization for a person of ordinary skill in the art (POSITA).
    • Expectation of Success (for §103 grounds): A POSITA would have reasonably expected to succeed in optimizing filler particle size and number, as this was a conventional technique for improving tape characteristics like handling and surface properties.

Ground 2: Obviousness over Inaba-283 in View of 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 Publication # H6-150286).
  • Core Argument for this Ground:
    • Prior Art Mapping: As in Ground 1, Inaba-283 provided the foundational four-layer tape structure, thickness, and coercivity. The Petitioner argued that Honda supplied the missing limitations by expressly teaching the use of inorganic filler particles within the claimed ranges for both size and number. Honda discloses a dual-layer substrate with a first layer containing particles of ~90 nm and a second layer containing particles of 150-450 nm. Petitioner argued that the mean particle diameter taken across these two layers would fall within the claimed 40-200 nm range. Furthermore, Honda’s disclosed areal particle densities were argued to correspond to a cross-sectional number within the claimed 10-200/100 µm² range when accounting for uniform particle dispersion.
    • Motivation to Combine (for §103 grounds): A POSITA, seeking to implement the tape taught in Inaba-283, would have been motivated to consult Honda for specific guidance on particle parameters. Inaba-283 teaches controlling surface roughness by varying filler size and amount but does not provide specific values, whereas Honda provides explicit, successful examples of doing so. The combination was presented as routine, applying Honda’s specific particle teachings to Inaba-283’s general tape structure to achieve a predictable improvement in surface characteristics.
    • Expectation of Success (for §103 grounds): Success was expected because both references concern multi-layer substrates for magnetic tapes and address the known technique of using fillers to control surface properties.

Ground 3: Obviousness over Inaba-244 in View of 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 Publication # 2000-30244), Nagasawa (European Application Publication # EP 1022106), and Masaki (Patent 5,698,311).
  • Core Argument for this Ground:
    • Prior Art Mapping: Inaba-244 disclosed a magnetic tape with a four-layer structure, an aramid substrate, and an overall thickness of 6.6 µm, but did not expressly teach adding filler particles to the substrate or the final magnetic layer coercivity. Nagasawa taught a method for producing aramid substrates that involved adding colloidal silica particles of a specific size (~80 nm) and concentration (0.035 wt%)—which falls within the ’256 patent’s claimed ranges and was shown to yield the claimed particle number. Masaki disclosed that an optimal magnetic layer should have a coercivity of 159-239 kA/m, identical to the range in claim 1.
    • Motivation to Combine (for §103 grounds): A POSITA starting with Inaba-244’s tape would combine its teachings with Nagasawa to improve substrate handling and prevent blocking, a known benefit of adding fillers. The manufacturing methods for the aramid substrate in Inaba-244 and Nagasawa were argued to be virtually identical, making the combination straightforward. The POSITA would then incorporate Masaki’s teachings to set the magnetic layer’s coercivity to a known optimal range for data stability and compatibility with recording heads.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success due to the significant overlap in the manufacturing processes described in Inaba-244 and Nagasawa, making the addition of fillers predictable.

4. Key Claim Construction Positions

  • "mean primary particle diameter" (Claims 1-6): Petitioner argued this term should be construed as the number-weighted mean of the diameters of non-aggregated particles in the nonmagnetic support, consistent with its conventional understanding in the art.
  • "number of particles...in the cross-section of said nonmagnetic support" (Claims 1-6): Petitioner argued that for a dual-layer substrate, as disclosed in references like Honda, this phrase refers to the mean number of particles taken across both layers. This construction was crucial for mapping Honda’s disclosures, which specified different particle densities in each of its two substrate layers, to the single range recited in the claims.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-6 of Patent 6,630,256 as unpatentable under 35 U.S.C. §103.