Promethean Ltd v. FlatFrog Laboratories Ab

1. Case Identification

• Case #: IPR2022-00065
• Patent #: 10,775,935
• Filed: October 16, 2021
• Petitioner(s): Promethean Ltd. and Promethean Inc.
• Patent Owner(s): FlatFrog Laboratories AB
• Challenged Claims: 1-3

2. Patent Overview

• Title: Method for Assembling a Touch Sensing Apparatus
• Brief Description: The ’935 patent discloses a method for assembling an optical touch-sensing device. The method’s central feature is configuring a frame assembly to support a touch plate in a way that induces a parabolic curvature in the plate’s touch surface, which purports to improve light transmission efficiency and enhance touch detection.

3. Grounds for Unpatentability

Ground 1: Claims 1 and 3 are obvious over Han in view of Shin-845

• Prior Art Relied Upon: Han (Application # 2019/0235701) and Shin-845 (Patent 9,291,845).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Han taught an infrared touch-sensitive panel comprising all elements of claim 1 except for the step of inducing the curvature. Han disclosed using a concavely curved cover glass to improve light efficiency and touch accuracy, and Petitioner’s analysis contended this disclosed curvature was parabolic in shape as required by the claim. Shin-845 was asserted to supply the missing element, as it explicitly taught a method of inducing a curvature in an initially flat cover glass by coupling it to a curved frame. Claim 3, which requires the plate to have a first curvature (e.g., flat) before assembly and a greater second curvature after, was allegedly met because Shin-845 taught starting with a flat plate.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Shin-845’s method with Han’s touch panel design. The motivation was to achieve the known manufacturing advantages and simplified process taught by Shin-845 (starting with a flat plate) while obtaining the known performance benefits (improved light efficiency) of the parabolic touch surface disclosed in Han.
  • Expectation of Success: The combination involved applying a known technique to a similar device to achieve predictable results. A POSITA would have reasonably expected that using Shin-845’s frame-induced curvature method on Han’s touch panel would successfully create the desired parabolic surface and simplify manufacturing.

Ground 2: Claims 1-3 are obvious over Cao-626 in view of Han and Shin-845

• Prior Art Relied Upon: Cao-626 (Patent 9,983,626), Han (Application # 2019/0235701), and Shin-845 (Patent 9,291,845).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Cao-626 disclosed an infrared touch device with a frame assembly used to control the curvature of a glass plate, specifically to force "four rising corners" of the glass to remain flat. While Cao-626 taught inducing flatness, it established the principle of using a frame to control glass curvature. Han was relied upon again for its teaching that a parabolic curvature enhances touch recognition and light efficiency. Shin-845 provided the specific teaching of how to modify a frame to induce a desired curve in an initially flat plate. Dependent claim 2, requiring curved frame edges, was allegedly rendered obvious by Eriksson (Patent 9,207,800), which taught curving a light guide frame to maintain a constant distance to the touch screen for better accuracy.
  • Motivation to Combine: A POSITA starting with the frame-based curvature control system of Cao-626 would be motivated to improve its performance by incorporating the advantageous parabolic curvature from Han. To achieve this, the POSITA would naturally look to known methods for inducing curvature, such as the manufacturing-simplified method taught in Shin-845, rather than continuing to induce flatness as in Cao-626.
  • Expectation of Success: The combination was presented as a predictable substitution of one design choice (inducing flatness) for another (inducing a parabolic curve) to achieve a known benefit, using a known implementation method.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including a combination of Cao-626, Han, and Zhao (Application # 2017/0123257), where Zhao was presented as an alternative to Shin-845 for teaching induced curvature. A further ground asserted claims 1-3 are obvious over Sasaki (Patent 4,751,379) in view of Han and Shin-845.

4. Key Claim Construction Positions

• "inducing a parabolic curvature in the touch surface": Petitioner, citing a District Court ruling in related litigation, construed this to mean "assembling the plate into the frame assembly induces a parabolic curvature in the touch surface." This construction emphasizes that the curvature is created during assembly, not by using a pre-curved plate.
• "parabolic curvature": Construed as "the curvature in the touch surface is substantially similar in shape to a mathematical parabola." This construction was key to Petitioner's argument that the circular curvature disclosed in Han meets the claim limitation, as its deviation from a true parabola was shown to be minimal.
• "curvature...after the plate is configured in the frame assembly": Petitioner and Patent Owner agreed this term means "the curvature in the touch surface, measured when the touch sensing apparatus is in its operative orientation, extends from one side of the touch surface to an opposite side."

5. Arguments Regarding Discretionary Denial

• Arguments Under §325(d): Petitioner argued against discretionary denial, asserting the grounds were not cumulative of art considered during prosecution. Petitioner contended the Examiner allowed the claims after failing to find prior art that taught inducing a parabolic curvature. The primary references for this limitation, Shin-845 and Zhao, were not before the Examiner. Furthermore, Petitioner argued the Examiner materially erred by overlooking the disclosure of a parabolic curvature in Han, which was one of over 700 references submitted in an Information Disclosure Statement (IDS) but not substantively examined.
• Arguments Under §314(a) (Fintiv Factors): Petitioner argued the Fintiv factors weighed in favor of institution.
  • Trial Proximity: Argued to be neutral because the scheduled district court trial was inherently speculative and likely to be rescheduled, whereas the PTAB’s deadline for a Final Written Decision (FWD) is fixed.
  • Investment and Overlap: Argued to favor institution because significant work remained in the district court case. Petitioner also made a stipulation that, if IPR were instituted, it would not pursue the same grounds in litigation or use Han, Cao-626, or Sasaki as primary references for invalidity, thereby mitigating overlap.

6. Relief Requested

• Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-3 of the ’935 patent as unpatentable under 35 U.S.C. §103.