Optimizing RFID reader duty cycle or power to preserve battery life

• US 7,825,806 B2
• Filed: 09/25/2007
• Issued: 11/02/2010
• Est. Priority Date: 09/25/2007
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Calvarese, Russell
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US11/860,958
• Publication Number:
  US 20090079571A1
• Time in Patent Office: 1,134 Days
• Field of Search: 340/572.1, 340/572.3, 340/572.4, 340/551, 340/10.33, 340/10.34
• US Class Current: 340/572.1
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10207 parameter settings related to power consumption of the interrogator
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles

Abstract

The duty cycle of a portable battery-powered RFID tag reader is reduced during time periods when it is less likely to produce a “read” in order to preserve battery life. The reader operates with an aggressive duty cycle during periods of a high probability of a tag read and reduces duty cycle during periods of a low probability of a tag read. In this manner a user does not perceive the reader to be sluggish. An alternative embodiment reduces peak operating power during time periods when a tag is less likely to produce a “read” in order to preserve battery life.

Claims

1. A method for operating an RFID reader, comprising:

first operating the RFID reader at a first duty cycle during a first period of time; and

second operating the RFID reader at a second duty cycle less than the first duty cycle during a second period of time characterized by a probability of obtaining a read being less than the probability of obtaining a read during the first period of time; and

wherein the second operating comprises operating the RFID reader at a decreasing duty cycle until a predetermined minimum duty cycle is reached.

4. A method according to claim 1 wherein the first operating occurs following a trigger event.

5. A method according to claim 1 wherein the first operating comprising operating the RFID tag reader in an autonomous mode without any trigger.

6. A method according to claim 1 further comprising:

operating the RFID tag reader at an increased duty cycle in response to a detection of some RFID tag activity.

7. A method according to claim 1 further comprising:

stepping down the duty cycle at predetermined points in time related to an occurrence of an event.

8. A method according to claim 7 wherein the event is a detection of RFID tag activity.

9. A method according to claim 7 wherein the event is a successful RFID tag read.

2. An RFID reader, comprising:

first means for operating the RFID reader at a first duty cycle during a first period of time; and

second means for second operating the RFID reader at a second duty cycle less than the first duty cycle during a second period of time characterized by a probability of obtaining a read being less than the probability of obtaining a read during the first period of time and

wherein the second operating means comprises means for operating the RFID reader at a decreasing duty cycle until a predetermined minimum duty cycle is reached.

3. A method for operating an RFID tag reader, comprising:

first operating the RFID tag reader at a first duty cycle;

in the event of a failure to detect RFID tag activity, reducing the duty cycle to a second duty cycle less than the first duty cycle; and

in the event of continued failure to detect RFID tag activity, reducing the duty cycle to a third duty cycle less than the second duty cycle.