PTAB

IPR2016-01426

D Link Systems Inc v. Chrimar Systems Inc

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Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Network Equipment for Detecting Devices via DC Current
  • Brief Description: The ’838 patent discloses a "central piece of network equipment," such as a hub, designed to work with Ethernet networks. The equipment detects different magnitudes of DC current flow over network cables to monitor and manage connected end devices, such as for asset tracking purposes.

3. Grounds for Unpatentability

Ground 1: Obviousness over Chang alone or in view of Patton - Claims 1, 2, 7, 26, 40, and 69 are obvious over Chang in view of Patton.

  • Prior Art Relied Upon: Chang (Patent 5,991,885) and Patton (Patent 5,121,482).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Chang discloses all limitations of the challenged claims. Chang teaches a network hub that detects the presence of remote devices and determines their functional protocol over twisted-pair cable. It does so by using different DC voltage levels (e.g., 3VDC vs. 5VDC) as a "presence signal" to distinguish between device types and control the application of electrical power. Petitioner asserted that detecting different voltage levels intrinsically discloses or renders obvious detecting different "magnitudes of DC current flow" as claimed, because voltage and current are directly related by Ohm's Law. To the extent this is not inherent, Petitioner argued that Patton, which Chang itself discusses, explicitly discloses a current-based detection method. Patton teaches using "current detection circuits" to interpret signals and identify the type of network connection (e.g., serial I/O vs. LAN I/O) based on impedance differences that result in low or high current.
    • Motivation to Combine (for §103 grounds): A POSITA would combine Patton’s current/impedance-based detection with Chang’s system because Chang itself identifies Patton as a known method for device detection. Both references address the same problem of device detection in LANs. A POSITA would have found it a simple and predictable substitution to use Patton's explicit current-detection circuitry to implement the device-distinguishing function in Chang's power-providing network hub.
    • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success, as combining Patton’s known current-detection circuit into Chang’s network hub system was a combination of known elements to achieve a predictable result.

Ground 2: Obviousness over Hunter in view of Bulan - Claims 1, 2, 7, 26, 40, and 69 are obvious over Hunter in view of Bulan.

  • Prior Art Relied Upon: Hunter (WO 96/23377) and Bulan (Patent 5,089,927).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Hunter discloses a "central piece of network equipment" (a hub) that provides "phantom power" over twisted-pair conductors in a LAN, including Ethernet systems, to power connected equipment. Hunter's primary goal is to provide power compatibly with existing communication standards. While Hunter provides the framework, Bulan was argued to supply the specific claimed detection mechanism. Bulan teaches a "current control apparatus" that includes a "current sensor" to continuously monitor various magnitudes of DC current flow over a transmission line. This monitoring is used to gather information about the connected equipment and control the power supply.
    • Motivation to Combine (for §103 grounds): A POSITA would combine Bulan's current-sensing technology with Hunter's power-over-Ethernet system to enhance its functionality. Hunter aims to provide power reliably, and incorporating Bulan's precise current monitoring and control apparatus would be a known technique to improve the system by allowing it to intelligently manage power based on the needs of the connected device, a clear improvement for Hunter's system.
    • Expectation of Success (for §103 grounds): The combination would have been straightforward, as it involved incorporating a known type of sensor and control circuitry (Bulan) into a known power-delivery system (Hunter) to achieve the predictable function of current-based power management.

4. Key Technical Contentions (Beyond Claim Construction)

  • Priority Date Challenge: Petitioner argued that the challenged claims of the ’838 patent were not entitled to the April 10, 1998 filing date of the provisional application. The petition asserted the provisional failed to provide adequate written description support for key limitations, such as controlling an electrical condition "in response to at least one of the magnitudes of the DC current flow," thereby making certain prior art references available.
  • Voltage Detection as a Proxy for Current Detection: A central technical argument, particularly for Ground 1, was that disclosing a system that detects different DC voltage levels (as in Chang) is sufficient to render obvious a claim to detecting different magnitudes of DC current flow. Petitioner contended that for any given circuit impedance, a change in voltage necessarily results in a proportional change in current, and a POSITA would have immediately understood this relationship.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1, 2, 7, 26, 40, and 69 of Patent 9,019,838 as unpatentable.