Tag communication device, tag moving direction detecting system and tag moving direction detecting method

• US 8,115,594 B2
• Filed: 05/08/2007
• Issued: 02/14/2012
• Est. Priority Date: 05/10/2006
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Koezuka, Yahiro, Iida, Kisho
• Primary Examiner(s): HOLLOWAY III, EDWIN C
• Application Number:
  US11/797,871
• Publication Number:
  US 20070273530A1
• Time in Patent Office: 1,743 Days
• Field of Search: 340/10.1, 340/572.1, 340/572.4, 340/572.7, 342/115, 342/158, 342/44
• US Class Current: 340/10.1
• CPC Class Codes: G01S 13/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: H04W 88/02 Terminal devices

Abstract

The invention provides a tag communication device, a tag moving direction detecting system and a tag moving direction detecting method able to detect the moving direction of a moving body attaching a RFID tag thereto by simple processing, and able to easily detect the moving direction even when its moving speed is increased. A scan antenna scans a beam of a transmitted radio wave toward a belt conveyer for conveying baggage with a RFID tag. ID is read from the RFID tag, and reading NO. and a scan angle are related and recorded to a measuring data table, and plot data are generated. These plot data are plotted in an XY coordinate system, and a plot graph is generated. Further, a linear approximate straight line is calculated from this plot graph, and a moving direction of the baggage is detected from an inclination value of the linear approximate straight line.

Claims

1. A tag communication device for performing wireless communications with a radio frequency identification (RFID) tag attached to a moving body via a radio wave, the tag communication device comprising:

an antenna that receives a plurality of information signals read from the RFID tag, each of the information signals including at least a tag identification, wherein the antenna is a scan antenna, having a plurality of antenna elements and wherein the scan antenna scans an area including a path of the RFID tag; and

a moving detection section for determining a moving direction of the RFID tag based on the plurality of information signals received by the antenna and time information corresponding to each of the wireless communications,

wherein the moving detection section is configured to calculate a linear approximate straight line to show the relation between a scan angle and the time information, and the moving detection section is configured to determine the moving direction of the RFID tag based on an inclination of the linear approximate straight line.

2. The tag communication device according to claim 1, wherein the time information specifies a time at which the RFID tag and the tag communication device performed the associated wireless communication.

3. The tag communication device according to claim 1, wherein the moving detection section determines the moving direction of the RFID tag based on a plurality of scan angles used by the scan antenna for scanning.

4. The tag communication device according to claim 1, wherein the moving detection section determines the moving direction of the RFID tag by calculating a moving locus of the RFID tag.

5. The tag communication device according to claim 1, wherein the antenna elements are two-dimensionally arrayed, and the scan antenna performs a two-dimensional scan of the path of the RFID tag.

6. The tag communication device according to claim 1, wherein elements of the antenna are constructed by a patch antenna.

7. The tag communication device according to claim 1, wherein the moving detection section calculates the moving direction of the RFID tag based on a plurality of sets of position information, wherein the position information has information relating to a position of the RFID tag.

8. The tag communication device according to claim 1, wherein the antenna scans a plurality of areas, based on a plurality of scan angles, to determine whether a RFID tag is present and the tag communication device determines the location of the RFID tag based on whether information signals are received from the RFID tag at each particular scan angle.

9. A tag communication system comprising:

a radio frequency identification (RFID) tag; and

a tag communication device that communicates with the RFID tag via wireless communications, the tag communication device further comprising;

an antenna that receives a plurality of information signals read from the RFID tag, each of the information signals including at least a tag identification, wherein the antenna is a scan antenna having a plurality of antenna elements and the scan antenna scans an area including a path of the RFID tag; and

a moving detection section for determining a moving direction of the RFID tag based on the plurality of information signals received by the antenna and time information corresponding to each of the wireless communications,

wherein the moving detection section is configured to calculate a linear approximate straight line to show the relation between a scan angle scanned by the scan antenna and the time information, and the moving detection section is configured to determine the moving direction of the RFID tag based on an inclination of the linear approximate straight line.

10. The system according to claim 9, wherein the time information specifies a time at which the RFID tag and the tag communication device performed the associated wireless communication.

11. The system according to claim 9, wherein the moving detection section calculates the moving direction of the RFID tag based on a plurality of sets of position information, wherein the position information has information relating to a position of the RFID tag.

12. The system according to claim 9, wherein the scan antenna receives a scan control signal based on the scan angle and scans for the RFID tag based on the scan control signal.

13. The system according to claim 9, wherein the antenna elements are two-dimensionally arrayed, and the scan antenna performs a two-dimensional scan of a path of the RFID tag.

14. A method of determining the moving direction of a radio frequency identification (RFID) tag comprising:

receiving a plurality of signals from the RFID tag;

receiving time information corresponding to each of the plurality of signals received from the RFID tag; and

determining a moving direction of the RFID tag based on the plurality of signals and time information, wherein said step of determining the moving direction comprises;

calculating a linear approximate straight line; and

determining the moving direction based on an inclination of the linear approximate straight line.

15. The method according to claim 14, further comprising scanning a plurality of locations of an area including a path of the RFID tag in response to control signals, wherein the control signals are based on a plurality of scan angles.