Background Object Sensor

• US 20120319819A1
• Filed: 06/17/2011
• Published: 12/20/2012
• Est. Priority Date: 06/17/2011
• Status: Active Grant

• Current Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Original Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Inventors: Tkachenko, Artem
• Granted Patent: US 8,890,684 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 11/10 using Doppler effect
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 13/876 Combination of several spaced transponders or reflectors of known location for determining the position of a receiver G01S13/874 takes precedence
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 13/92 for velocity measurement
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G06K 7/10425 the interrogation device being arranged for interrogation of record carriers passing by the interrogation device
• CPC Class Codes: G06Q 10/08 Logistics, e.g. warehousing, loading or distribution; Inventory or stock management
• CPC Class Codes: G08B 13/248 EAS system combined with another detection technology, e.g. dual EAS and video or other presence detection system

Abstract

An RFD reader includes a transceiver configured to receive a first radio frequency signal reflected off at least one surface to provide baseline signal information and a second radio frequency signal reflected off the at least one surface and an object to provide further signal information. A comparator is configured to compare the baseline signal information and the further signal information to provide a signal comparison. A processor is configured to detect the presence of the object in accordance with the signal comparison. A determination is made whether the object is in motion in accordance with the signal comparison. The determination whether the object is in motion is made in accordance with a continuous fluctuation of the second radio frequency signal. A determination whether the object is no longer in motion is made in accordance with an ending of the continuous fluctuation of the second radio frequency signal.

Claims

1. An RFID reader, comprising:

a transceiver configured to receive a first radio frequency signal reflected off at least one surface to provide baseline signal information;

the transceiver being further configured to receive a second radio frequency signal reflected off the at least one surface and an object to provide further signal information;

a comparator configured to compare the baseline signal information and the further signal information to provide a signal comparison; and

a processor configured to detect the presence of the object in accordance with the signal comparison.

2. The RFID reader of claim 1, wherein the processor is further configured to determine whether the object is in motion in accordance with the signal comparison.

3. The RFID reader of claim 2, wherein the processor is further configured to determine whether the object is in motion in accordance with a continuous fluctuation of the second radio frequency signal.

4. The RFID reader of claim 3, wherein the processor is further configured to determine whether the object is no longer in motion in accordance with an ending of the continuous fluctuation of the second radio frequency signal.

5. The RFID reader of claim 1, wherein at least one of the first and second radio frequency signals is a simulated electronic product code signal.

6. The RFID reader of claim 1, wherein the comparator is further configured to compare received signal strengths.

7. The RFID reader of claim 6, wherein a received signal strength of the first radio frequency signal comprises a first sum of signal strengths of a plurality of component signals received by the RFID receiver.

8. The RFID reader of claim 7, wherein a received signal strength of the second radio frequency signal comprises a second sum of signal strengths equal to the first sum of signal strengths and at least one additional signal strength corresponding to a radio frequency signal reflected off the object.

9. The RFID reader of claim 6, wherein the comparator is further configured to compare a received signal strength of at least one of the first and second radio frequency signals in accordance with a plurality of time samples.

10. The RFID reader of claim 1, wherein the comparator is further configured to compare signal phase information.

11. The RFID reader of claim 10, wherein the processor is further configured to determine a signal phase of at least one of the first and second radio frequency signals in accordance with a plurality of time samples.

12. The RFID reader of claim 1, further comprising a tag inventory performed by the RFID reader.

13. The RFID reader of claim 12, wherein the first radio frequency signal comprises a signal with a power level of approximately 30 dBm and the second radio frequency signal comprises a signal with a power level less than approximately −

5 dBm.

14. The RFID reader of claim 12, further comprising an interleaving of the signal comparing and a plurality of tag inventories.

15. The RFID reader of claim 1, further comprising a marker tag wherein the baseline signal information is determined in accordance with a marker tag to provide marker baseline information.

16. The RFID reader of claim 15, wherein the processor is further configured to determine the presence of the object in accordance with the marker baseline information.

17. The RFID reader of claim 1, wherein the processor is further configured to determine a distance to the object in accordance with the signal comparison.

18. The RFID reader of claim 17, wherein the processor is further configured to determine a threshold received signal strength and the distance to the object in accordance with the threshold received signal strength.

19. A method for detecting the presence of an object having at least one surface in a monitored region in an RFID communication system, comprising:

receiving a first radio frequency signal reflected off the at least one surface to provide baseline signal information;

receiving a second radio frequency signal reflected off the at least one surface and the object to provide further signal information;

comparing the baseline signal information and the further signal information to provide a signal comparison; and

detecting the presence of the object in accordance with the signal comparison.

20. The method for detecting the presence of an object of claim 19, further comprising determining whether the object is in motion in accordance with the signal comparison.