Tag communication apparatus, control method for tag communication apparatus, computer readable medium for tag communication control and tag communication control system

• US 7,573,418 B2
• Filed: 06/20/2005
• Issued: 08/11/2009
• Est. Priority Date: 06/22/2004
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Kawai, Takehiro, Saito, Keisuke, Okamura, Shinichiro
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US11/155,776
• Publication Number:
  US 20050280538A1
• Time in Patent Office: 1,513 Days
• Field of Search: 342/126, 340/572, 455/562
• US Class Current: 342/42
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• 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

Abstract

A direction estimating section estimates the incoming direction of a radio wave from an RFID tag in each of antennas. A position calculating section calculates the position of the RFID tag on the basis of the incoming direction of the radio wave estimated in the direction estimating section.

Claims

1. An apparatus configured to communicate with an RFID (Radio Frequency Identification) tag through a radio wave, said apparatus comprising:

a plurality of antenna elements, each of which is configured to receive the radio wave from the RFID tag;

a direction estimating section configured to estimate an incoming direction of the radio wave from the RFID tag at each of the antenna elements thereby obtaining estimated directions;

a power measuring section configured to measure a power of the radio wave received by each of the antenna elements, thereby obtaining a measured power ratio;

a position calculating section configured to calculate a position of the RFID tag based on the estimated directions; and

a power ratio estimating section configured to estimate a ratio of powers to be received by the antenna elements based on the calculated position of the RFID tag, as an estimated power ratio;

wherein the position calculating section is configured to compare the measured power ratio with the estimated power ratio to verify the calculated position of the RFID tag.

2. The apparatus or claim 1, wherein the direction estimating section estimates the incoming direction of the radio wave by null scanning.

3. A method for controlling an apparatus comprising a plurality of antenna elements each of which receives a radio wave from an RFID (Radio Frequency Identification) tag to communicate with the RFID tag, said method comprising:

estimating an incoming direction of the radio wave from the RFID tag at each of the antenna elements, thereby obtaining estimated directions;

measuring a power of the radio wave received by each of the antenna elements, thereby obtaining a measured power ratio ;

calculating a position of the RFID tag based on the estimated directions;

estimating a ratio of powers to be received by the antenna elements based on the calculated position of the RFID tag, as an estimated power ratio; and

comparing the measured power ratio with the estimated power ratio to verify the calculated position of the RFID tag.

4. The method of claim 3, wherein the step of estimating an incoming direction is performed by executing a null scanning operation.

5. A computer readable medium comprising a program including instructions for controlling an apparatus comprising a plurality of antenna elements each of which is configured to receive a radio wave from an RFID (Radio Frequency Identification) tag to communicate with the RFID tag, said instructions comprising:

estimating an incoming direction of the radio wave from the RFID tag at each of the antenna elements, thereby obtaining estimated directions;

measuring a power of the radio wave received by each of the antenna elements, thereby obtaining a measured power ratio;

calculating a position of the RFID tag based on the estimated directions;

estimating a ratio of powers to be received by the antenna elements based on the calculated position of the RFID tag, as an estimated power ratio; and

comparing the measured power ratio with the estimated power ratio to verify the calculated position of the RFID tag.

6. The computer readable medium of claim 5, wherein the method step of estimating an incoming direction is performed by executing a null scanning operation.

7. A tag communication control system comprising:

an apparatus configured to communicate with an RFID (Radio Frequency Identification) tag through a radio wave, said apparatus including;

a plurality of antenna elements each of which is configured to receive the radio wave from the RFID tag;

a direction estimating section configured to estimate an incoming direction of the radio wave from the RFID tag at each of the antenna elements thereby obtaining estimated directions;

a power measuring section configured to measure a power of the radio wave received by each of the antenna elements, thereby obtaining a measured power ratio;

a position calculating section configured to calculate a position of the RFID tag based on the estimated directions; and

a power ratio estimating section configured to estimate a ratio of powers to be received by the antenna elements based on the calculated position of the REID tag, as an estimated power ratio;

a management section for managing at least one object correlated with the RFID tag based on a result obtained from the communication with the RFID tag by the apparatus;

wherein the position calculating section is configured to compare the measured power ratio with the estimated power ratio to verify the calculated position of the RFID tag.

8. The tag communication control system as claimed in claim 7, wherein

the management section includes a photographing section which photographs a space region, and a photographing control section which controls at least one of a photographing direction and a photographing range in the photographing section, and

the photographing control section performs the photographing control based on the position of the RFID tag specified by the apparatus.

9. The tag communication control system of claim 7, wherein the direction estimating section is configured to estimate an incoming direction by executing a null scanning operation.