Tag communication apparatus and tag communication system

• US 8,072,328 B2
• Filed: 03/05/2008
• Issued: 12/06/2011
• Est. Priority Date: 03/05/2007
• Status: Active Grant

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Ando, Koji, Kawai, Takehiro
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): MEHRAVARI, PETER CYRUS
• Application Number:
  US12/042,847
• Publication Number:
  US 20080224828A1
• Time in Patent Office: 1,371 Days
• Field of Search: 340/572.1, 340/572.7, 340/10.2, 340/10.4, 340 32- 324, 340 36- 363, 340/825.2, 455/456.1, 455/562.1, 342/90, 342/91, 342/93, 342/121, 342/146, 342/156, 342/383, 342/456
• 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 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

A first tag communication apparatus is adapted to perform radio communications with a second tag communication apparatus and an RFID tag provided on a moving object. A controller is operable to cause an antenna to transmit first radio waves while changing a first direction that the first radio waves are transmitted. A receiver is operable to receive a second radio waves transmitted from the second tag communication apparatus. An extractor is operable to extract, from the second radio waves, synchronizing information indicative of a timing that the second tag communication apparatus changes a second direction that the second radio waves are transmitted therefrom. A synchronizer is operable to synchronize a timing that the controller changes the first direction with the timing that the second tag communication apparatus changes the second direction, based on the synchronizing information.

Claims

1. A first tag communication apparatus, adapted to perform radio communications with a second tag communication apparatus and an RFID tag provided on a moving object, the first tag communication apparatus comprising:

an antenna;

a controller, operable to cause the antenna to transmit first radio waves while changing a first direction that the first radio waves are transmitted;

a receiver, operable to receive a second radio waves transmitted from the second tag communication apparatus and to receive a tag information transmitted from the RFID tag in response to the first radio waves transmitted from the antenna;

an extractor, operable to extract, from the second radio waves, synchronizing information indicative of a timing that the second tag communication apparatus changes a second direction that the second radio waves are transmitted therefrom;

a synchronizer, operable to synchronize a timing that the controller changes the first direction with the timing that the second tag communication apparatus changes the second direction, based on the synchronizing information; and

a generator, operable to associate the tag information with temporal information indicative of when the receiver receives the tag information, and to generate a plurality of data sets including the temporal information and angle information which is indicative of the direction that the first radio waves are transmitted when the receiver receives the tag information.

2. The first tag communication apparatus as set forth in claim 1, wherein the extractor is operable to extract the synchronizing information from a reception level of the second radio waves.

3. The first tag communication apparatus as set forth in claim 2, wherein the extractor is operable to extract the synchronizing information from a temporal variation of the reception level of the second radio waves.

4. The first tag communication apparatus as set forth in claim 1, wherein the extractor is operable to extract the synchronizing information from data transmitted from the second tag communication apparatus.

5. The first tag communication apparatus as set forth in claim 1, wherein

the first tag communication apparatus further comprises:

an estimator, operable to perform linear approximation with respect to a relationship between the temporal information and the angle information, and to estimate a direction that the moving object moves from a gradient of a line obtained by the linear approximation.

6. A tag communication system, adapted to perform radio communications with an RFID tag provided on a moving object, the tag communication system comprising:

a pair of tag communication apparatuses, disposed so as to oppose each other, each of which is adapted to perform radio communications with the RFID tag and comprises;

an antenna;

a controller, operable to cause the antenna to transmit radio waves while changing a direction that the radio waves are transmitted;

a receiver, operable to receive a tag information transmitted from the RFID tag in response to the radio waves transmitted from the antenna;

a generator, operable to associate the tag information with temporal information indicative of when the receiver receives the tag information, and to generate a plurality of data sets including the temporal information and angle information which is indicative of the direction that the radio waves are transmitted when the receiver receives the tag information; and

an estimator, operable to perform linear approximation with respect to a relationship between the temporal information and the angle information, and to estimate a direction that the moving object moves from a gradient of a line obtained by the linear approximation.