PTAB

IPR2017-00362

Fieldpiece Instruments Inc v. Twin Rivers Engineering Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Infrared Leak Detector
  • Brief Description: The ’993 patent describes a portable, handheld infrared (IR) leak detector for identifying refrigerant gases. The invention uses a system of optical filters, including a bandpass filter for wavelengths between approximately 8 to 10 microns, to selectively detect refrigerants and minimize false alarms from other compounds.

3. Grounds for Unpatentability

Ground 1: Obviousness over Wong/Wallack/Sibley Combination - Claims 2, 3, and 9 are obvious over Wong and Wallack or Sibley in view of Bley, Horiba, and Johnson Controls.

  • Prior Art Relied Upon: Wong (Patent 5,889,199), Wallack (Patent 3,832,548), Sibley (Patent 4,649,711), Bley (Patent 6,635,875), Horiba (Patent 4,236,827), and Johnson Controls (a 1996 product bulletin).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Wong taught the claimed portable handheld IR leak detector with a sampling chamber, IR emitter, and sensor. The key limitation upheld during a prior reexamination—a second filter passing an IR energy range of approximately 8 to 10 microns—was explicitly taught by both Wallack (8.4 to 9.4 microns) and Sibley (9.75 to 10.25 microns) for detecting fluorocarbon refrigerants. Petitioner argued Horiba taught using two filters to improve detection accuracy and reduce interference. For claim 9, Johnson Controls taught a portable detector with a three-level sensitivity switch, meeting the claim’s requirement for at least three setting levels.
    • Motivation to Combine (for §103 grounds): A person of ordinary skill in the art (POSITA) would combine the base detector of Wong with the specific refrigerant filters from Wallack and Sibley to improve the detection of known fluorocarbons, a known problem in the field. The use of a two-filter system as taught by Horiba was a known technique for enhancing signal-to-noise ratio. A POSITA would also incorporate the multi-level sensitivity switch from Johnson Controls to make the detector more versatile for finding leaks of varying sizes.
    • Expectation of Success (for §103 grounds): Petitioner argued success was expected as the combination involved applying known filter technologies to a standard IR detector to achieve the predictable function of improved selectivity and sensitivity.

Ground 2: Obviousness over Wong/Moyer/Johnson Combination - Claim 6 is obvious over Wong or Moyer and Johnson Controls in view of McFadden, Liebermann, and Blades.

  • Prior Art Relied Upon: Wong (Patent 5,889,199), Moyer (Patent 6,255,652), Johnson Controls (bulletin), McFadden (Patent 6,489,787), Liebermann (Patent 3,742,475), and Blades (Patent 6,114,700).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed the audio output features of claim 6. Petitioner contended that Wong and Moyer provided the base portable IR gas leak detector. The claimed "zero control setting" was explicitly taught by Blades to null out DC drift. Johnson Controls taught an audio output with a low repetition rate at idle (3-4 Hz), while McFadden and Liebermann both taught audio alarms with a click rate proportional to the gas concentration.
    • Motivation to Combine (for §103 grounds): A POSITA would combine a base detector (Wong or Moyer) with the proportional audio alarm from McFadden or Liebermann to provide intuitive, non-visual feedback for locating leaks. It would have been obvious to adapt the idle chirp rate taught by Johnson Controls to the claimed 1 Hz for user comfort and to implement a zeroing circuit from Blades to ensure signal stability, a common goal in sensor design. The shift from a 1 Hz idle rate to a 2 Hz initial leak detection rate was argued as an obvious design choice to create a clearly discernible alert.
    • Expectation of Success (for §103 grounds): Success was expected because combining known audio feedback mechanisms with a standard detector was a well-established practice for improving usability, and incorporating a zeroing circuit was a routine method for enhancing electronic stability.

Ground 3: Obviousness over Wong/Blades/Kobayashi Combination - Claim 7 is obvious over Wong in view of Blades and Kobayashi or Craft.

  • Prior Art Relied Upon: Wong (Patent 5,889,199), Blades (Patent 6,114,700), Kobayashi (JP Publication No. 10-038930), and Craft (Patent 3,701,022).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground focused on the claimed "signal detection accumulator" with a "forward biased detector circuit" and a "zero circuit." Petitioner argued that Wong's RC circuit (resistor 48, capacitor 50) functioned as a signal accumulator. While Wong lacked a forward-biased diode, both Kobayashi and Craft taught peak detector circuits that explicitly used forward-biased diodes to reliably capture positive signal peaks. Blades was again cited for its teaching of a "zero circuit" that references ground to compensate for DC drift.
    • Motivation to Combine (for §103 grounds): A POSITA would be motivated to improve the sensitivity of Wong’s accumulator, which sacrificed sensitivity by not rectifying the signal. Incorporating a forward-biased diode rectifier, as taught by Kobayashi or Craft, was a known and straightforward method to improve the capture of weak signals from small leaks. A POSITA would then logically add the zeroing circuit from Blades to stabilize the more sensitive detector circuit.
    • Expectation of Success (for §103 grounds): The combination was a predictable integration of standard electronic components (rectifiers, integrators, zeroing circuits) to improve the performance of a sensor circuit, with each component performing its expected function.

4. Key Claim Construction Positions

  • "a signal detection accumulator" (claim 7): Petitioner proposed this term be construed as "a circuit that holds a detected signal long enough to be processed." This construction was central to arguing that the RC integrator circuit in Wong met the limitation.
  • "zero control setting" (claim 6) / "zero circuit" (claim 7): Petitioner proposed this term be construed as "a control in the circuitry that nulls out any DC drift in the detector" and "a circuit that nulls out any DC drift in the detector," respectively. This construction was critical for applying the teachings of Blades to the claimed invention.

5. Arguments Regarding Discretionary Denial

  • Petitioner argued that institution was proper because the petition presented new prior art and arguments not previously before the Office during prosecution or reexamination. It contended that the new evidence and expert declaration showed why the examiner’s prior assumptions about the functionality of the cited art (particularly Wong) were incorrect, thus overcoming the basis for the claims’ previous allowance.

6. Relief Requested

  • Petitioner requests institution of inter partes review (IPR) and cancellation of claims 2, 3, 6, 7, and 9 as unpatentable.