PTAB

IPR2019-00278

Elo Touch Solutions, Inc. v. 3M Innovative Properties Company

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1. Case Identification

2. Patent Overview

  • Title: Touch Screen Sensor Having Varying Sheet Resistance
  • Brief Description: The ’799 patent describes touch screen sensors that use electrically conductive micropatterns, such as metallic meshes, instead of continuous transparent conducting oxide (TCO) coatings. This approach is intended to allow for the engineering of electrical and optical properties, specifically by creating different regions of the sensor with varying sheet resistance values.

3. Grounds for Unpatentability

Ground 1: Obviousness over Binstead and Yoshikawa - Claims 10-20 are obvious over Binstead in view of Yoshikawa.

  • Prior Art Relied Upon: Binstead (Application # 2006/0278444) and Yoshikawa (Japanese Application # JP 2004-192093).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Binstead taught a touch panel sensor with an electrically conductive micropattern comprising different regions with different conductivity levels to control the capacitive signal. However, Binstead did not explicitly disclose the specific conductor widths or high open area fractions (OAFs) recited in independent claim 10. Yoshikawa was argued to cure this deficiency by disclosing transparent metal mesh touch screens with specific, optimized properties, including conductor widths of 5µm and an OAF of 98%, which meets the limitations of claim 10 (e.g., "at least 90% open area").
    • Motivation to Combine: A POSITA would combine Binstead's sensor design with Yoshikawa's mesh parameters to improve the functionality and manufacturability of Binstead's sensor. Yoshikawa provided an explicit commercial motivation to use its micropattern meshes to create highly transparent and scalable conductors with easily controllable resistivity, which would have been seen as a predictable way to implement the variable conductivity regions described in Binstead.
    • Expectation of Success: A POSITA would have had a high expectation of success, as combining known methods from Yoshikawa (controlling mesh parameters) with the system of Binstead to achieve a desired, predictable result (a touch sensor with specific OAF and variable resistance) was a matter of routine design optimization.

Ground 2: Obviousness over Okumura and Hurst - Claims 1-2 and 10-19 are obvious over Okumura in view of Hurst.

  • Prior Art Relied Upon: Okumura (Japanese Application # JP 2006-344163) and Hurst (Patent 7,800,589).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Okumura taught a touch sensor using a metal mesh micropattern as an improvement over TCO sensors, including the use of different mesh shapes and line widths to achieve different sheet resistances. However, Okumura did not explicitly teach the "periodic sheet resistance along the long axis" required by independent claims 1 and 10. Hurst was argued to teach this missing element by disclosing a technique to correct for electric field non-uniformities (pincushion effect) by dividing a sensor into a grid of high, intermediate, and low conductivity regions, creating the claimed periodic resistance profile.
    • Motivation to Combine: A POSITA would combine these references to solve well-known problems in the art. Okumura's mesh provided a superior alternative to the ITO layers used in Hurst, while Hurst's grid technique would solve the pincushion effect and enable multi-touch sensing, both known issues with basic electrostatic capacitive sensors like Okumura's. The combination would linearize equipotential lines and improve sensing accuracy.
    • Expectation of Success: The combination would have yielded predictable results. Hurst provided an express motivation to improve sensor accuracy, and Okumura provided an improved physical structure (metal mesh) for implementing Hurst's concept of patterned resistivity.

Ground 3: Obviousness over Okumura, Hurst, and Kang - Claims 3, 6, 8-9, and 20 are obvious over Okumura in view of Hurst and further in view of Kang.

  • Prior Art Relied Upon: Okumura (Japanese Application # JP 2006-344163), Hurst (Patent 7,800,589), and Kang (Patent 6,445,426).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground built on the Okumura/Hurst combination to address limitations in independent claim 3, which requires a "periodic series of breaks in the traces." Petitioner argued that while the Okumura/Hurst combination taught periodic resistance, it did not explicitly do so via selective breaks. Kang was argued to teach this limitation by disclosing a touch panel with a "plurality of through holes" (i.e., selective breaks) periodically spaced in a conductive layer for the express purpose of varying resistance.
    • Motivation to Combine: Kang provided an express motivation for its technique: varying resistance values by varying the dimensions and intervals of through-holes. A POSITA would have recognized Kang's method as a predictable and effective way to implement the periodic resistance pattern of Hurst within the metal mesh structure of Okumura. This provided an additional, well-known method for tailoring resistance beyond just altering mesh geometry or material.
    • Expectation of Success: A POSITA would have had a strong expectation of success in applying Kang's well-known technique of creating breaks to control resistivity to the Okumura/Hurst design, as it was a known and predictable method for achieving a desired resistance profile.

  • Additional Grounds: Petitioner asserted additional obviousness challenges based on combinations including Hotelling (’369 WO publication) to teach mutual capacitance measurements; Yoshikawa to teach specific open area fractions; Chen (Application # 2007/0018076) to teach specific trace widths; and Kable (Patent 4,665,283) to teach coupling to a drive device for mutual capacitance measurements.

4. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-20 of the ’799 patent as unpatentable.