PTAB

IPR2021-01167

InductEV Inc v. WiTricity Corp

Key Events

Petition

petition Intelligence

Title: Adaptive Wireless Energy Transfer System
Brief Description: The ’581 patent discloses a wireless power transfer system that controls a power converter to operate in different output power modes. The mode selection is responsive to changes in the coupling strength between the transmit and receive antennas, which varies with the distance between them.

Prior Art Relied Upon: Sato (Application # 2010/0259109).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Sato’s wireless power transmission system disclosed every limitation of the challenged claims. Sato described a power converter, comprising an oscillator and an amplifier, that is configurable to switch between distinct output power modes (e.g., “low,” “middle,” and “high” power). This mode switching is performed to maintain a necessary reception power as the transmission distance between the transmit and receive antennas changes. Petitioner asserted that changing modes based on transmission distance inherently meets the limitation of selecting modes based on a change in coupling coefficient, as the coupling coefficient is a direct function of distance. Sato's resonant circuits, operating frequency, and transmit/receive functionality were also alleged to map directly onto the claim limitations.

Prior Art Relied Upon: Sato (Application # 2010/0259109), with additional references demonstrating the general knowledge of a person of ordinary skill in the art (POSITA), including Jin (Patent 7,956,495) and Partovi (Patent 8,169,185).
Core Argument for this Ground:
- Prior Art Mapping: This ground built upon the disclosures in Sato. Dependent claim 10 adds a "mechanical device configured to adjust a position of the charging base antenna." Dependent claim 12 recites that the system’s "operating frequency is in a range of about 20 kHz to about 60 kHz."
- Motivation to Combine: Petitioner contended a POSITA would combine Sato’s system with a mechanical antenna positioner to solve the known problem of misalignment between transmit and receive coils, thereby improving power transfer efficiency. This was a common and predictable solution for charging portable devices of various sizes. For claim 12, Petitioner argued that selecting an operating frequency in the 20-60 kHz range was a simple design choice. A POSITA would be motivated to select this range to balance power efficiency against switching losses and to operate above the human audible range, as was well-known in the art.
- Expectation of Success: A POSITA would have had a high expectation of success in implementing these modifications, as they involved applying known techniques to a known system to achieve predictable results.

Prior Art Relied Upon: Julstrom (Patent 8,022,775).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Julstrom’s inductively coupled battery charging system taught all limitations of these claims. Julstrom disclosed a power converter (a half-bridge inverter) that changes its output power mode based on the distance between the transmit and receive coils. A controller adjusts the inverter’s pulse-width modulated (PWM) signal to reduce the drive voltage (changing from a high-power mode to a low-power mode) as the coils move farther apart. This adjustment maintains a uniform charging current. Petitioner asserted this control scheme, which is based on a measurement of the drive current, is directly indicative of the coupling coefficient, thus satisfying the claim limitation. Julstrom further disclosed a resonant frequency of 23 kHz, falling within the range recited in claim 12.
Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 4) for claims 10, 46-48, 50, and 51 over Julstrom, relying on similar design modification theories as presented in Ground 2 for adding a mechanical positioner.

Petitioner argued that several terms in apparatus claims 46 and 50 should be construed as means-plus-function limitations under §112(6), with their scope limited to the corresponding structures disclosed in the ’581 patent and their equivalents.
“means for converting a power...” (claims 46, 50): Petitioner identified the corresponding structures as an oscillator with an amplifier, a half-bridge inverter, or a full-bridge inverter, as described in the specification of the ’581 patent.
“means for configuring the converting means...” (claim 46): Petitioner identified the corresponding structure as a controller configured to control the output power mode (e.g., by changing the voltage transformation ratio) based on a measurement indicative of the coupling coefficient between the antennas.

Petitioner argued that discretionary denial would be inappropriate.
Against denial under §325(d), Petitioner asserted that the petition presented prior art (Sato and Julstrom) and arguments that were not before the Examiner during the original prosecution.
Against discretionary denial under Fintiv, Petitioner argued that the co-pending district court case was in its earliest stages. At the time of filing, Petitioner had not yet responded to the complaint, no substantive issues had been decided, and the parties' investment in the litigation was minimal.

Petitioner requests the institution of an inter partes review and the cancellation of claims 1, 9-10, 12-13, 18, 36-37, 43-44, and 46-51 of Patent 8,884,581 as unpatentable.