Light selectable radio frequency identification tag and method therefor

• US 5,874,724 A
• Filed: 01/10/1997
• Issued: 02/23/1999
• Est. Priority Date: 01/10/1997
• Status: Expired due to Term

• Current Assignee: Toshiba Global Commerce Solutions Holdings Corporation (Toshiba Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Cato, Robert Thomas
• Primary Examiner(s): Le, Thien Minh
• Application Number:
  US08/781,755
• Time in Patent Office: 774 Days
• Field of Search: 235/492, 235/382, 235/375, 235/454, 235/486, 235/487, 235/380
• US Class Current: 235/492
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/0728 the arrangement being an optical or sound-based communication interface
• 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

Abstract

A radio frequency identification (RFID) tag includes a photodetector which is receptive to a predefined wavelength and a control circuit which is receptive to a flash pattern of a light source. The RFID tag responds to a predefined command from RFID base station only if the photodetector included in the tag was activated by a light signal having an appropriate wavelength and flash pattern. During or after the photodetector circuit is activated, an operator of a pulsed light source then interrogates a single RFID tag with an unknown identification by using a pulsed light source to illuminate the particular tag. Only the tag illuminated by the pulsed light source responds to the reader.

Claims

1. A radio frequency identification tag, comprising:

means for receiving a command signal;

a detector for detecting a directional signal and generating a detected signal in response to the directional signal; and

a digital control logic circuit coupled to the detector for receiving the detected signal and coupled to the means for receiving the command signal, the digital control logic circuit performing an operation in response to the command signal when the detected signal has a first value, wherein the command signal is provided by a radio frequency identification tag base station external to the radio frequency identification tag.

2. The radio frequency identification tag of claim 1 wherein the directional signal is provided by a light source.

3. The radio frequency identification tag of claim 1 wherein the detected signal has the first value when the detector detects an input signal having a predetermined wavelength and frequency.

4. The radio frequency identification tag of claim 1 wherein the digital control logic circuit detects an input signal having a predetermined pattern.

5. The radio frequency identification tag of claim 4, wherein the digital control logic circuit performs the operation when the input signal has the predetermined pattern.

6. The radio frequency identification tag of claim 1, further comprising:

a digitizer coupled to the detector for receiving the detected signal, the digitizer digitizing the detected signal to generate a digitized signal.

7. The radio frequency identification tag of claim 1 wherein the digital control logic circuit generates a command output signal during performance of the operation.

8. The radio frequency identification tag of claim 7 further comprising:

a radio frequency sub-system coupled to the digital control logic circuit for receiving the command output signal; and

an antenna coupled to the radio frequency sub-system for selectively communicating the command output signal.

9. The radio frequency identification tag of claim 7 wherein the digital control logic circuit generates a plurality of control signals during performance of the operation.

10. The radio frequency identification tag of claim 9, further comprising:

a memory coupled to the digital control logic circuit for receiving the plurality of control signals.

11. The radio frequency identification tag of claim 10 wherein the plurality of control signals enable the memory to output a data value stored therein.

13. The radio frequency identification tag of claim 10 wherein the plurality of control signals enable the memory to store a data value therein.

14. The radio frequency identification tag of claim 13 wherein the command output signal provides an acknowledge signal to a base station external to the radio frequency identification tag.

15. The radio frequency identification tag of claim 1 wherein the detector detects a pointing beam of the directional signal.

12. A radiofrequency identification tag, comprising:

means for receiving a command signal;

a detector for detecting a directional signal and generating a detected signal in response to the directional signal; and

a digital control logic circuit coupled to the detector for receiving the detected signal and coupled to the means for receiving the command signal, the digital control logic circuit performing an operation in response to the command signal when the detected signal has a first value, wherein the digital control logic circuit generates a command output signal during performance of the operation, wherein the digital control logic circuit generates a plurality of control signals during performance of the operation, wherein the radio frequency identification tag further comprises a memory coupled to the digital control logic circuit for receiving the plurality of control signals, wherein the plurality of control signals enable the memory to output a data value stored therein, wherein the command output signal provides the data value to a base station external to the radio frequency identification tag.

16. A radio frequency identification tag, comprising:

means for receiving a command signal;

a detector for detecting a directional signal and generating a detected signal in response to the directional signal; and

a digital control logic circuit coupled to the detector for receiving the detected signal and coupled to the means for receiving the command signal, the digital control logic circuit performing an operation in response to the command signal when the detected signal has a first value, wherein the detector detects a pointing beam of the directional signal, wherein the detector detects a helper beam of the directional signal and wherein the digital control logic circuit indicates the helper beam has been detected.

17. The radio frequency identification tag of claim 16 wherein the digital control logic circuit indicates that the directional signal should be moved such when the helper beam has been detected.

18. A method for performing radio frequency identification in a radio frequency identification tag, comprising the steps of:

receiving a first command signal to enable the radio frequency identification tag to operate in a first mode of operation;

detecting a directional signal and generating a detected signal in response to the directional signal;

performing a first radio frequency identification operation in response to the first command signal when the detected signal has a first value; and

receiving a second command signal to enable the radio frequency identification tag to operate in a second mode of operation.

19. The method of claim 18, further comprising the step of:

generating the detected signal having the first value when the directional signal is a light having a preselected wavelength.

20. The method of claim 18, further comprising the step of:

generating the detected signal having the first value when the directional signal is a light having a preselected pattern.

21. The method of claim 18, further comprising the step of:

generating a plurality of control signals during performance of the first radio frequency operation.

22. The method of claim 18, further comprising the step of:

generating a command output signal during performance of the first radio frequency identification operation.

23. The method of claim 21, further comprising the steps of:

coupling a memory to the control signal to receive the plurality of control signals;

enabling the memory to output a data value stored therein in response to the plurality of control signals; and

providing the data value to a base station external to the radio frequency identification tag.

24. The method of claim 21, further comprising the steps of:

coupling a memory to the control signal to receive the plurality of control signals;

enabling the memory to store a data value therein in response to the plurality of control signals; and

providing an acknowledge signal to a base station external to the radio frequency identification tag.

25. A radio frequency identification tag comprising:

a radio frequency sub-system for receiving a command signal from a source external to the radio frequency identification tag;

a detector for detecting a directional signal and generating a detected signal in response to the directional signal; and

a digital control logic circuit coupled to the detector for receiving the detected signal, the digital control logic circuit performing an operation in response to the command signal when the detected signal has a first value.

26. A method for performing radio frequency identification in a radio frequency identification tag, comprising the steps of:

receiving from a source external to the radio frequency identification tag a command signal;

detecting a directional signal and generating a detected signal in response to the directional signal; and

performing a radio frequency identification operation in response to the command signal when the detected signal has a certain value.