Radio-frequency tag communication device, radio-frequency tag communication system, and radio-frequency tag detecting system

• US 8,149,091 B2
• Filed: 11/10/2006
• Issued: 04/03/2012
• Est. Priority Date: 05/13/2004
• Status: Active Grant

• Current Assignee: Brother Kogyo Kabushiki Kaisha
• Original Assignee: Brother Kogyo Kabushiki Kaisha
• Inventors: Nagai, Takuya, Kiyohara, Yuji
• Primary Examiner(s): Nguyen, Nam V
• Application Number:
  US11/558,727
• Publication Number:
  US 20070120650A1
• Time in Patent Office: 1,971 Days
• Field of Search: 342/42, 342/44, 342/51, 235/226, 340 101- 105, 340/572.1, 340/572.4
• US Class Current: 340/10.1
• 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 7/10356 using a plurality of antennas, e.g. configurations including means to resolve interference between the plurality of antennas

Abstract

A radio-frequency tag communication device permitting a radio-frequency tag communication system to have a sufficiently large area of communication, with a minimum required number of interrogators. The radio-frequency tag communication device includes a transmission control portion operable to control transmission of a transmitted signal, so as to prevent overlapping an area of communication of the radio-frequency tag communication device and an area of communication of another radio-frequency tag communication device, making it possible to maximize a spacing distance between the adjacent radio-frequency tag communication devices, and to effectively prevent concurrent receptions of the transmitted signals by the plurality of radio-frequency tags. Namely, the radio-frequency tag communication device permits the radio-frequency tag communication system to have a sufficiently large area of communication with a minimum required number of interrogators.

Claims

1. A radio-frequency tag communication device arranged to transmit a transmitted signal toward a radio-frequency tag, and to receive a reply signal transmitted from the radio-frequency tag in response to the transmitted signal, for communication with the radio-frequency tag, said radio-frequency tag communication device comprising:

a transmission control portion operable to control transmission of said transmitted signal, so as to prevent overlapping of an area of communication of said radio-frequency tag communication device and an area of transmission of another radio-frequency tag communication device; and

a radio-frequency-tag communication judging portion operable to determine whether there is any radio-frequency tag which exists within said area of communication of said radio-frequency tag communication device and which is under communication with said another radio-frequency tag communication device, and wherein said transmission control portion restricts the transmission of the transmitted signal when an affirmative determination is obtained by said radio-frequency-tag communication judging portion.

2. The radio-frequency tag communication device according to claim 1, wherein said transmission control portion controls the transmission of said transmitted signal such that the transmitted signal is transmitted at a timing different from a timing of transmission of the transmitted signal from said another radio-frequency tag communication device.

3. The radio-frequency tag communication device according to claim 1, further comprising a plurality of antenna elements through which the transmitted signal is transmitted, and said transmission control portion controls a direction of transmission of the transmitted signal by controlling a phase of the transmitted signal to be transmitted through each of said plurality of antenna elements, to thereby change said area of communication.

4. The radio-frequency tag communication device according to claim 1, wherein said transmission control portion controls the direction of transmission of the transmitted signal to change the area of transmission of said radio-frequency tag communication device when the affirmative determination is obtained by said radio-frequency-tag communication judging portion.

5. The radio-frequency tag communication device according to claim 1, further comprising a plurality of antenna elements through which said reply signals are received from said radio-frequency tags, and a reception control portion operable to control a direction of reception of the reply signals by controlling a phase of each of the reply signals received through said plurality of antenna elements.

6. The radio-frequency tag communication device according to claim 5, wherein said reception control portion is operable to control an amplitude of each of the transmitted signals to be transmitted from said plurality of antenna elements, and said reception control portion is operable to control an amplitude of each of the reply signals received through said plurality of antenna elements.

7. The radio-frequency tag communication device according to claim 5, wherein said area of communication of said radio-frequency tag communication device which is used for the determination by said radio-frequency-tag communication judging portion is determined on the basis of said direction of reception of said reply signals which is controlled by said reception control portion.

8. The radio-frequency tag communication device according to claim 5, wherein said transmission control portion controls the phase of each of the transmitted signals to be transmitted through said plurality of antenna elements such that the direction of transmission of the transmitted signals is coincident with the direction of reception of the reply signals.

9. The radio-frequency tag communication device according to claim 5, wherein said reception control portion controls the phase of each of the reply signals received by said plurality of antenna elements such that the direction of reception of the rely signals is coincident with the direction of transmission of the transmitted signals.

10. The radio-frequency tag communication device according to claim 1, further comprising a radio-frequency-tag-position detecting portion operable to detect a position of the radio-frequency tag existing within said area of communication of said radio-frequency tag communication device.

11. A radio-frequency tag communication system comprising a plurality of radio-frequency tag communication devices each constructed as defined in claim 1, and wherein said transmission control portions of the plurality of radio-frequency tag communication devices of said plurality of radio-frequency tag communication devices transmit the transmitted signals in synchronization with each other, so as to prevent overlapping areas of communication of said plurality of radio-frequency tag communication devices.

12. The radio-frequency tag communication system according to claim 11, wherein said transmission control portions of said plurality of radio-frequency tag communication devices control the transmission of said transmitted signals in synchronization with each other, such that the transmitted signals are transmitted by said radio-frequency tag communication devices at respective different timings.

13. The radio-frequency tag communication system according to claim 11, wherein said transmission control portions of said plurality of radio-frequency tag communication devices control directions of transmissions of said transmitted signals, in synchronization with each other.

14. A radio-frequency tag detecting system comprising:

a plurality of stationary radio-frequency tag communication devices which are located at respective predetermined positions and which are arranged to transmit transmitted signals toward a predetermined radio-frequency tag and to receive a reply signal transmitted from the radio-frequency tag, for communication with the radio-frequency tag;

a portable radio-frequency tag communication device, which is provided with an identification tag which has the same arrangement as the radio-frequency tag and is arranged to transmit a further transmitted signal toward said radio-frequency tag and to receive a further reply signal transmitted from the radio-frequency tag, for detecting the radio-frequency tag located within areas of communication of said plurality of stationary radio-frequency tag communication devices;

a transmission control portion operable to control transmission of said transmitted signals such that said plurality of stationary radio-frequency tag communication devices and said portable radio-frequency tag communication device transmit said transmitted signals at respective different timings; and

a judging portion operable to determine whether said identification tag provided on said portable radio-frequency tag communication device and the radio-frequency tag to be detected are located within one of the areas of communication of the plurality of stationary radio-frequency tag communication devices;

wherein said transmission control portion controls the transmission of the transmitted signal from said portable radio-frequency tag communication device such that the transmitted signal is transmitted only after an affirmative determination is obtained by said judging portion.

15. The radio-frequency tag detecting system according to claim 14, wherein the area of communication of said portable radio-frequency tag communication device is narrower than the areas of communication of said plurality of stationary radio-frequency tag communication devices.

16. The radio-frequency tag detecting system according to claim 14, wherein said transmission control portion controls the timings of transmission of the transmitted signals from said plurality of stationary radio-frequency tag communication devices, so as to prevent concurrent transmission of the transmitted signals toward an area in which the areas of transmission of the plurality of radio-frequency tag communication devices overlap each other.

17. The radio-frequency tag detecting system according to claim 14, which comprises a plurality of portable radio-frequency tag communication devices each arranged as defined in claim 14.

18. The radio-frequency tag detecting system according to claim 14, wherein said portable radio-frequency tag communication device includes an input portion for manually designating the radio-frequency tag to be detected.

19. The radio-frequency tag detecting system according to claim 14, wherein said portable radio-frequency tag communication device includes a display portion operable to indicate a direction in which the radio-frequency tag to be detected is located.

20. The radio-frequency tag detecting system according to claim 14, wherein said portable radio-frequency tag communication device includes an indicator portion operable to provide a predetermined indication when an affirmative determination is obtained by said judging portion.

21. The radio-frequency tag detecting system according to claim 14, wherein said portable radio-frequency tag communication device includes a plurality of antenna elements, and a directivity control portion operable to control directivity of said plurality of antenna elements.