Thermally controlled duty cycle regulation in an RFID module

• US 8,199,015 B2
• Filed: 06/03/2009
• Issued: 06/12/2012
• Est. Priority Date: 06/03/2009
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bellows, David E., Strzelczyk, Martin J., Sandler, Robert I
• Primary Examiner(s): Lu, Shirley
• Application Number:
  US12/477,367
• Publication Number:
  US 20100308973A1
• Time in Patent Office: 1,105 Days
• Field of Search: 340/572.1, 340/595, 340/445
• 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

Abstract

A system and methods for measuring the temperature of an RFID reader module and inserting a delay in the RFID reader'"'"'s duty cycle to prevent the RFID reader from initiating a thermal shutdown. The system and methods are self-adaptable, therefore incurring the benefit regardless of the design of the RFID reader host and its associated heat sink. The system and methods also provide for archiving the collected data and analyzing the data providing the ability to improve the design of the RFID reader host.

Claims

1. A computer-readable media encoded with a computer program for a system for preventing thermal shutdown of radio frequency identification (RFID) reader by automatically adjusting the duty cycle of the RFID reader, the system comprising:

a temperature measurement component for determining the temperature of the RFID reader; and

a control component for providing a duty cycle delay value storage location, calculating the duty cycle delay value based on the measured temperature and delaying the duty cycle based on the calculated delay value, the control component comprises a delay loop integrated into a proportional-integral-derivative (PID) loop, the measured temperature to be input to the PID which then provides the duty cycle delay value output for delaying the RFID reader duty cycle in proportion to the measured temperature.

2. The system of claim 1, further comprising an analysis component operable to notify a host device of the RFID reader with an alarm indicating possible RFID reader failure in response to the measured temperature and a rate of RFID tag reading.

3. The system of claim 1, wherein the PID loop is tuned to characteristics of the RFID reader.

4. The system of claim 1, the system further comprises a second temperature measurement component for determining an ambient temperature, and further comprises an analysis component for calculating an adjustment to the calculated duty cycle delay value based on a change in ambient temperature and a predicted effect the change in ambient temperature will have on the RFID reader temperature so as to provide predictive control of the RFID reader temperature.

5. The system of claim 4, the analysis component predicting a new duty cycle delay value based on historical duty cycle delay value trends.

6. The system of claim 5, the analysis component for analyzing the measured temperature with regard to a rate of read requests from a host of the RFID reader and the ambient temperature and provide predictive control for preventing thermal shutdown of the RFID reader.

7. The system of claim 1, wherein the RFID reader sets a number of inventory rounds to perform.

8. The system of claim 1, the delay loop comprises programming a timer with a duty cycle delay value time and waiting for notification of timer completion before continuing the RFID reader duty cycle.

9. The system of claim 1, wherein the RFID reader sets a number of antenna cycles that switch antennas to inspect another different aspect of RFID tags.

10. A method for preventing thermal shutdown of a radio frequency identification (RFID) reader component, the method comprising:

employing a processor to execute the following computer executable acts stored on a computer readable medium, the processor including a delay loop integrated into a proportional-integral-derivative (PID) loop;

receiving a read RFID tag command from a host device;

measuring the temperature of the RFID reader, the measured temperature to be input to the PID;

calculating a duty cycle delay value based on the measured temperature, the duty cycle delay value being in proportion to the measured temperature and being output from the PID;

reading data from an RFID tag; and

delaying the duty cycle based on the calculated delay value from the PID.

11. The method of claim 10, further comprising measuring the ambient temperature and predicting adjustments to the calculated duty cycle delay value based on a change in ambient temperature and a predicted effect the change in ambient temperature will have on the RFID reader temperature so as to provide predictive control of the RFID reader temperature.

12. The method of claim 10, the method further comprises analyzing archived temperature data and predicting a duty cycle delay value based on the archived temperature data trend.

13. A system for automatically preventing thermal shutdown of radio frequency identification (RFID reader component, the system comprising:

means for receiving a read RFID tag command from a host device;

means for measuring the temperature of the RFID reader;

a delay loop integrated into a proportional-integral-derivative (PID) loop, the measured temperature to be input to the PID, whereupon the PID calculating a duty cycle delay value based on the measured temperature, the duty cycle delay value being in proportion to the measured temperature and being output from the PID;

means for reading data from an RFID tag; and

means for adjusting the duty cycle delay based on the calculated delay value from the PID.

14. The system of claim 13, wherein the means for adjusting includes.

15. The system of claim 13, further comprising:

means for measuring the ambient temperature; and

means for adjusting the calculated duty cycle delay value based on a change in measured ambient temperature and a predicted effect the change in ambient temperature will have on the RFID reader temperature so as to provide predictive control of the RFID reader temperature.

16. The system of claim 14, further comprising:

means for analyzing the archived temperature data and the duty cycle delay data and generating a report based on a heatsink efficiency in a current environmental setting of RFID reader operation; and

means for automatically distributing the generated report to other locations.

17. A method for preventing thermal shutdown of radio frequency identification (RFID) reader component, the method comprising:

employing a processor to execute the following computer executable acts stored on a computer readable medium, the processor including a delay loop integrated into a proportional-integral-derivative (PID) loop;

receiving a read trigger from a host device;

operating the RFID reader at maximum read rate;

measuring the temperature of the RFID reader, the measured temperature to be input to the PID;

calculating a duty cycle delay value based on the measured temperature, the duty cycle delay value being in proportion to the measured temperature and being output from the PID; and

adding the calculated delay value from the PID to the duty cycle if the RFID reader temperature approaches a value indicating thermal shutdown before the end of the triggered read.