# US 2013/0154801 A1 · Method and apparatus for reading radio frequency identification tags with lowest power consumption > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0154801 A1 - Document ID: US20130154801A1 - Status: Published application - Kind: A1 - Application number: 13/329,366 - Filed: 2011-12-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: Symbol Technologies, Inc. - Inventors: Michael O'Haire - Web page: https://patentgrep.com/patent/US20130154801A1 ## CPC - G06K 7/10009: {sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves} - G06K 7/10118: {the sensing being preceded by at least one preliminary step} - G06K 7/10158: {methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field} - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS ## Abstract A method and apparatus for selectively reading radio frequency identification device (RFID) tags by an RFID reader includes the RFID reader transmitting an interrogation signal at each of a plurality of power levels beginning with a lowest power level and sequentially increasing power of the transmitted interrogation signal to a highest power level. The RFID reader receives, in response to transmitting the interrogation for at least one of the power levels, at least one data signal from each RFID tag within a read zone of the RFID reader, wherein each of the data signals contains stored data corresponding to the RFID tag responding to the transmission of the interrogation signal. The RFID reader selectively reads the stored data contained in the data signals received from the responding RFID tags. ## Claims ### Claim 1 A method for selectively reading radio frequency identification device (RFID) tags by an RFID reader, the method comprising: transmitting, by the RFID reader, an interrogation signal at each of a plurality of power levels beginning with a lowest power level and sequentially increasing power of the transmitted interrogation signal to a highest power level; receiving, in response to transmitting the interrogation signal for at least one of the power levels, at least one data signal from each RFID tag within a read zone of the RFID reader, wherein each of the data signals contains stored data corresponding to the RFID tag responding to the transmission of the interrogation signal; and selectively reading the stored data contained in the data signals received from the responding RFID tags. ### Claim 2 (depends on 1) The method of claim 1, wherein selectively reading comprises reading the stored data for each of the responding RFID tags at only one of the power levels at which the interrogation signal is transmitted. ### Claim 3 (depends on 2) The method of claim 2, wherein selectively reading further comprises tracking the RFID tags that have responded to the transmission of the interrogation signal. ### Claim 4 (depends on 3) The method of claim 3, wherein tracking comprises increasing the power level used to transmit the interrogation signal when there is an absence of newly identified RFID tags responding to the interrogation or when there is an absence of data signals received in response to the interrogation signal for a current power level. ### Claim 5 (depends on 4) The method of claim 4, wherein selectively reading further comprises terminating reading if there is an absence of newly identified RFID tags responding to the interrogation signal and the interrogation signal has been transmitted at the highest of the plurality of the power levels. ### Claim 6 (depends on 2) The method of claim 2, wherein the stored data for each of the RFID tags is read only at an initial power level to which the RFID tag responds. ### Claim 7 (depends on 2) The method of claim 2 further comprising: at each power level at which the interrogation signal is transmitted: maintaining an identity of the RFID tags responding to the interrogation signal at the power level; and reading the stored data contained in the data signal received from newly identified RFID tags. ### Claim 8 (depends on 1) The method of claim 1, wherein, for each of the responding RFID tags, the data signal is received in response to the interrogation signal at only one of the power levels, and selectively reading comprises reading the stored data from all of the responding RFID tags. ### Claim 9 (depends on 2) The method of claim 2 further comprising instructing each of the RFID tags to respond to the interrogation signal only once. ### Claim 10 (depends on 9) The method of claim 9, wherein the instructing comprises, for each of the RFID tags: commanding the RFID tag to set an internal flag to control the RFID tag to respond to the interrogation signal with the data signal only once. ### Claim 11 A radio frequency identification (RFID) tag reader comprising: a transceiver configured to transmit an interrogation signal at a selected transmission power level and to receive responses from RFID tags in response to the interrogation signal; and a processor operatively coupled to the transceiver and configured to determine the selected transmission power level, wherein the selected transmission power level is sequentially increased from a lowest power level to a highest power level, and wherein the processor is further configured to perform a read algorithm at each selected transmission power level to read, at least once, responses from each of the RFID tags. ### Claim 12 (depends on 11) The RFID reader of claim 11, wherein at least one of the RFID tags is an Electronic Product Code Generation 2 RFID tag, wherein the processor is further configured to control each of the RFID tags to set an internal flag that causes the RFID tags to respond only once to the interrogation signal. ### Claim 13 A non-transient computer readable storage medium having computer-readable code stored thereon for programming a computer to perform a method for selectively reading radio frequency identification (RFID) tags, the method comprising: transmitting an interrogation signal at each of a plurality of power levels beginning with a lowest power level and sequentially increasing power of the transmitted interrogation signal to a highest power; receiving, in response to transmitting the interrogation signal for at least one of the power levels, at least one data signal from each RFID tag within a read zone of an RFID reader, wherein each of the data signals contain stored data corresponding to the RFID tag responding to the transmission of the interrogation signal; and selectively reading the stored data contained in the data signals received from the responding RFID tags. ### Claim 14 (depends on 13) The non-transient storage medium of claim 13, the method further comprising commanding each of the RFID tags to set an internal flag to control responsiveness of the RFID tag to the interrogation signal. ### Claim 15 (depends on 14) The non-transient storage medium of claim 14, wherein the internal flag causes each of the RFID tags to respond to the interrogation signal with the data signal only once. ### Claim 16 (depends on 13) The non-transient storage medium of claim 13, the method further comprising maintaining an identity of the RFID tags responding to the interrogation signal at each of the power levels and reading the stored data contained in the data signal received from newly identified RFID tags. ### Claim 17 (depends on 13) The non-transient storage medium of claim 13, wherein selectively reading further comprises tracking the RFID tags that have responded to the transmission of the interrogation signal. ### Claim 18 (depends on 17) The non-transient storage medium of claim 17, wherein tracking comprises increasing the power level used to transmit the interrogation signal when there is an absence of newly identified RFID tags responding to the interrogation signal or when there is an absence of data signals received in response to the interrogation signal for a current power level. ### Claim 19 (depends on 18) The non-transient storage medium of claim 18, wherein selectively reading further comprises terminating reading when there is an absence of newly identified RFID tags responding to the interrogation signal and the interrogation signal has been transmitted at the highest of the plurality of the power levels. ### Claim 20 (depends on 13) The non-transient storage medium of claim 13, wherein the stored data for each of the RFID tags is read only at an initial power level to which the RFID tag responds.