PTAB

IPR2023-01428

Millerknoll Inc v. Dejule Aaron

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1. Case Identification

2. Patent Overview

  • Title: Apparatus with Weight Responsive Changeable Adjusting Characteristics
  • Brief Description: The ’498 patent relates to mechanisms for office chairs that automatically adjust the amount of force required to recline based on a user’s weight. The disclosed mechanism uses a user's weight to compress a weighing spring, which in turn reduces the effective length of a separate tilting spring (e.g., a leaf spring), thereby increasing the resistance to tilting for heavier users.

3. Grounds for Unpatentability

Ground I: Anticipation of Claims 1-10, 14-15, and 19-22 by Takamatsu ’318

  • Prior Art Relied Upon: Takamatsu ’318 (Patent 5,080,318).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Takamatsu ’318 discloses a chair with every element of the challenged claims. The reference shows a seat (first component) and a chair back (second component) that can tilt relative to the seat. Its adjusting mechanism includes "weight responsive compression springs" (a weighing spring) and "second tilting control plate springs" (a tilting spring). When a user sits, their weight displaces the seat downward, causing pivoting bent links to pull on a band connected to contact pins on the plate springs. This movement shortens the effective length of the plate springs, increasing the force required for a user to recline. Petitioner contended this structure performs the identical function of the claimed "adjusting assembly," thereby anticipating claim 1 and its dependents.

Ground II: Anticipation of Claims 1 and 18 by Takamatsu ’372

  • Prior Art Relied Upon: Takamatsu ’372 (Patent 5,348,372).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Takamatsu ’372 independently anticipates claims 1 and 18. This reference discloses a chair mechanism that uses a rack and pinion system. When a user's weight depresses the seat, a "first rack" descends and engages a "first pinion," rotating a pinion assembly. This rotation causes "second racks" to advance horizontally, moving a load-applying pin that shortens the effective length of the torsion coil springs resisting the backrest's tilt. Petitioner argued this mechanism meets all limitations of claim 1. Furthermore, the explicit disclosure of a "first rack," "first pinion," "second pinions," and "second racks" constitutes the "cooperating toothed elements" required by dependent claim 18.

Ground III: Obviousness of Claim 18 over Takamatsu ’318 in view of Takamatsu ’372

  • Prior Art Relied Upon: Takamatsu ’318 (Patent 5,080,318) and Takamatsu ’372 (Patent 5,348,372).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Takamatsu ’318 discloses all elements of independent claim 1. Takamatsu ’372 discloses the additional limitation of claim 18: "cooperating toothed elements" (i.e., its rack and pinion system) that perform the same function as Takamatsu ’318’s pivoting links—converting vertical seat movement into horizontal movement of a component that adjusts tilting resistance. The proposed combination is a simple substitution of one known mechanical linkage for another to achieve a predictable result.
    • Motivation to Combine: A POSITA would combine the references to increase the sensitivity of the weight-adjustment mechanism. Takamatsu ’318 states an express goal of making its mechanism "highly sensitive to weight variations." Takamatsu ’372 teaches that its rack and pinion gear system, by virtue of its gear ratios, can "increase the sensitivity" of the adjustment, allowing small changes in user weight to produce a perceivable change in tilting resistance. A POSITA would therefore be motivated to incorporate the superior sensitivity of the ’372 gear system into the base mechanism of ’318 to better achieve ’318's own stated objective.
    • Expectation of Success: A POSITA would have had a reasonable expectation of success in making this substitution. The function of converting vertical to horizontal motion is well-understood, and both pivoting links and rack-and-pinion systems were well-known components for this purpose in the field of seating mechanisms. The substitution would not alter the fundamental operation of the Takamatsu ’318 chair and would predictably result in a more sensitive adjustment mechanism.

4. Key Claim Construction Positions

  • "adjusting assembly": Petitioner argued this term should be construed as a means-plus-function element under 35 U.S.C. §112(f). Petitioner contended the term is a "nonce" term that recites a purely functional result without reciting sufficient structure for performing that function. The corresponding structure disclosed in the ’498 patent was identified as the combination of: (1) a tilting spring (in the form of leaf springs, coil springs, or torsion components) that resists backrest movement, and (2) a weighing spring (in the form of coil springs) that deforms in proportion to user weight, along with equivalents thereof. This construction is central to the anticipation arguments, which map the prior art structures to this definition.
  • "on the frame": Petitioner proposed construing this term to mean "supported directly or indirectly by the frame." This construction was based on the ’498 patent’s own figures, which only show the seat and backrest components being indirectly supported by the frame via intervening parts. Petitioner also noted that during prosecution, the examiner adopted this broader interpretation, and the applicants did not dispute it, which provides further support for the proposed construction.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-10, 14-15, and 18-22 of Patent 10,292,498 as unpatentable.