Impinj, Inc.

California Institute of Technology

Other

Impinj, International Ltd.

Synopsys, Inc.

Virage Logic Corporation

Impmj, Inc.

Inpinj, Inc.

Christopher J Diorio

Scott A Cooper

Harley K Heinrich

Todd E Humes

Theron Stanford

Ronald A Oliver

Alberto Pesavento

Matthew Robshaw

John D Hyde

Kurt Eugene Sundstrom

Tan Mau Wu

Ronald Lee Koepp

Jay A Kuhn

Chad A Lindhorst

Shailendra Srinivas

Carver A Mead

Paul F Dietrich

Kambiz Rahimi

William T Colleran

Gregory T Kavounas

Joel D Peshkin

Aanand Esterberg

Charles J T Peach

Bradley A Minch

Paul E Hasler

Yael Gregory Maguire

Vadim Gutnik

Omer Onen

Troy N Gilliland

Mike Thomas

Joe Tarantino

Ali Aiouaz

Frederic J Bernard

Frédéric J Bernard

Terry D Hass

Jaideep Mavoori

Sandesh Doddameti

Balaji Shyamkumar

Jayasuryan Iyer

Vadim Lobanov

Brent A Picasso

Arthur Gustav Enyedy

Daniel Bowman

Larry Arnstein

David Kaplan

Michael H Thomas

Vincent C Moretti

Thomas G Anderl

John Schroeter

Omar Khwaja

Charles Peach

Matthew J B Robshaw

Casey M Hagen

Andrew Friefeld

Amir Sarajedini

Michael J Dacquisto

Joseph Baird

Miguel E Figueroa

Shail Srinivas

Yanjun Ma

Bin Wang

Kaila Raby

Seth W Bridges

Jay Michael Fassett

Christopher Dean Peterson

Lawrence Frederick Arnstein

David Ord

Ron Oliver

Jesse Paul Cooke

Ron Koepp

Dan Bowman

Dimitri C Desmons

RFID systems may be configured to use session-dependent replies. When an RFID tag is involved in a certain inventorying session, the tag may respond to inventorying commands with a reply that is at least partly generated based on the session. For example, the tag may generate a reply with a string that has parity based on the session or includes an identifier for the session. The string may be a random number, a tag identifier or item identifier, or any other suitable data sent from the tag.

RFID systems with session-dependent replies

RFID-tagged items can be filtered based on relevance estimation or user input. A device reads digital identifiers for multiple RFID-tagged items. The device estimates and selects an item that an individual desires based on one or more metrics, then presents data about the selected item to the individual. If the device receives feedback that the selected item is not the desired item, then the device may estimate and select another item and/or present information about multiple items to allow the individual to select the desired item. When the desired item is selected, the device may perform some associated action.

User-filtered RFID inventory

RFID tags may compensate for non-RFID power sources by automatically enforcing data or state persistence even while powered. A tag may measure a time interval between successive detected modulated reader transmissions. If the interval exceeds a minimum time, then the tag may deassert a protocol flag, erase data, and/or change tag operating states, even if the tag would normally not perform these actions while powered.

RFID tags enforcing persistence while powered

RFID readers may be configured to supply power to tags during frequency hops. When a reader is supplying power to a passive RFID tag via a first RF waveform having a first radio frequency and determines that it is to frequency-hop, the reader may determine whether the tag requires power during the hop. If so, the reader begins (or continues) to synthesize a second RF waveform with a second radio frequency while also synthesizing the first RF waveform, and frequency-hops by transitioning from transmitting the first RF waveform to transmitting the second RF waveform such that the power transmitted during the transition is sufficient for the tag to operate.

Fast frequency switching for RFID applications

An RFID IC may operate at a relatively low clock frequency while impedance matching to an antenna is being tuned to increase the amount of power that the IC can extract from an incident RF wave. A tuning circuit tunes the impedance matching by adjusting a variable impedance coupling the IC and the antenna. The IC may power-up with a low clock frequency or reduce its current clock frequency to a lower clock frequency prior to tuning or during the tuning process, and may increase its clock frequency upon completion of tuning or during the tuning process.

RFID tag clock frequency reduction during tuning

A Radio Frequency Identification (RFID) tag IC stores an identifier and a check code. The IC determines whether the stored identifier is corrupted by comparing it to the check code. If the stored identifier does not correspond to the check code then the IC may terminate operation or indicate an error. The IC may also reconstruct the correct identifier from the check code.

RFID integrated circuit identifier self-check

An authentication method includes RFID tags authenticating RFID readers. A tag sends a tag identifier and a reader challenge to a reader in response to one or more commands from the reader. The reader then either derives a response to the reader challenge itself or has a verification authority derive the response. The response may be derived from parameter(s) in the reader challenge, and may be derived using a cryptographic key. The reader then sends the response to the tag along with one or more commands. The tag verifies the response before executing action(s) associated with the command(s).

Enhanced RFID tag authentication

An RFID loss-prevention system (LPS) may monitor RFID-tagged items in a facility. An RFID reader transmits a first inventory command configured to cause tags in a first state to respond, receive a reply from a first tag, determine that the first tag has a low transition risk, and cause the first tag to switch to a second state. The reader may also receive a reply from a second tag, determine that the second tag has a high transition risk, and cause the second tag to remain in the first state. The reader may then transmit a second inventory command configured to cause tags in the first state to respond, receive a reply from the second tag in response to the second inventory command, determine that the second tag has inappropriately exited the facility, and issue an alert.

RFID loss-prevention based on transition risk

RFID ICs sense and indicate changes in their surrounding environment, such as changes in temperature, humidity, chemical presence, RF signals, and similar. An RFID IC indicates when a significant environmental change has occurred, for example by adjusting the value of a flag, writing data to memory, transmitting a message to an external entity, exiting a sleep state, and/or responding repeatedly to an inventorying reader. In some cases, RFID IC actively notifies an external entity that a significant environmental change has been sensed. For example, RFID IC may alert the external entity by participating in a special inventory process meant for RFID ICs sending environmental change. The RFID IC may alert the external entity by interjecting itself into an inventory round, re-participating in an inventory round, refraining from entering a sleep state after inventorying, and/or adjusting timing of a scheduled reply to communicate with an RFID reader ahead of schedule.

Environment-based RFID IC behavior

RFID tags capable of transitioning between a private state and one or more public states are provided. In the private state, tags may participate in an inventory round without restriction. In a public state, tags may be prevented from participating in an inventory round, allowed to participate without providing actual identifying information, or allowed to participate providing an alternate identifier. Whether and how the tag responds in a public state may depend on certain conditions including if one or more of the tag's flags are asserted or deasserted. A reader may select a public tag for inventorying by verifying itself, and the tag then asserting or deasserting one or more of its flags accordingly. The asserted or deasserted flag(s) may be used to determine whether and how a tag in a public state participates in an inventory round.

RFID tags with public and private inventory states

A method is provided to determine unique identifiers. A physical item has an RFID integrated circuit (IC) having a unique identifier and a secret. The RFID IC may be configured to provide an identifier portion and a response to a previously sent challenge, where the identifier portion by itself is insufficient to completely identify the IC or item and the response is based on the challenge and the secret. Attempts are made to verify the response using a set of potential secrets determined using the identifier portion. If the response is successfully verified using a certain secret, the secret may then be used to determine one or more other identifier portions. The unique, complete identifier may then be determined from a combination of at least the identifier portions.

Item identification via RFID tag secret

RFID tag ICs may be configured with privacy modes. When a tag IC is in a privacy mode, it will not respond to commands unless a previous command includes correct verification information or specifies a recycling indicator of the tag IC. If the previous command includes correct verification information, then the tag IC will respond to one or more subsequent commands as normal, for example by responding with one or more identifiers. If the previous command does not include correct verification information but specifies a recycling indicator and the privacy mode is recycling-enabled, the tag IC may respond to one or more subsequent commands with recycling information. The recycling information identifies whether or how an item associated with the RFID IC can be recycled or disposed but does not otherwise identify the RFID IC or item. Otherwise, the tag IC may remain silent.

RFID ICs with privacy modes

Growing community of inventors

Shoreline, WA, United States of America

Christopher J Diorio