RF identification system with restricted range

• US 6,097,301 A
• Filed: 04/04/1996
• Issued: 08/01/2000
• Est. Priority Date: 04/04/1996
• Status: Expired due to Term

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Communications, Inc. (Micron Technology, Inc.)
• Inventors: Tuttle, John R.
• Primary Examiner(s): ZIMMERMAN, BRIAN A
• Application Number:
  US08/628,125
• Time in Patent Office: 1,580 Days
• Field of Search: 340/825.54, 340/572, 340/505, 340/432, 340/572.7, 340/572.8, 340/693.9, 340/10.1, 342/51, 342/42
• US Class Current: 340/693.9
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• 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: G08B 21/023 Power management, e.g. system sleep and wake up provisions
• CPC Class Codes: G08B 21/0258 System arrangements wherein both parent and child units can emit and receive
• CPC Class Codes: G08B 21/0266 System arrangements wherein the object is to detect the exact distance between parent and child or surveyor and item
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A method of adjusting the 2-way communication range of an RFID system to assist a human operator to individually handle and interrogate a plurality of tagged objects, such as suitcases, that each include an RFID tag transceiver. An RFID interrogator transceiver is mounted on the human operator. The 2-way communication range between the interrogator transceiver and the tag transceivers is adjusted to only slightly exceed the closest distance between the interrogator and the tag while the operator is handling the tagged object. Preferably, the 2-way communication range is short enough that other tagged objects will remain outside the communication range and will not respond to messages from the interrogator. Another aspect of the invention is a method of verifying whether an object to be transported has reached its intended destination. In this aspect, an interrogator transceiver at a first destination interrogates an RFID tag transceiver on the object, and in response the tag transmits its intended destination.

Claims

1. A method of adjusting the two-way communication range of an RFID system to permit a person to individually handle and interrogate each one of a plurality of tagged objects, each tagged object having an RFID tag transceiver, comprising the steps of:

mounting on the person an RFID interrogator transceiver having an antenna;

mounting the antenna of the interrogator transceiver near one hand of the person, so that the person can reduce the distance between the antenna and a tag transceiver to a minimum distance by extending his hand toward the tag transceiver;

mounting on each tagged object an RFID tag transceiver, wherein

each tag transceiver is characterized by a set of one or more performance parameters which control a reliable two-way communications range between that tag transceiver and the interrogator transceiver, and

the interrogator transceiver is characterized by a set of one or more performance parameters which control the reliable two-way communications range between the interrogator transceiver and any of the tag transceivers; and

adjusting at least one of the performance parameters so that the reliable two-way communications range between the interrogator transceiver and the transceiver of each of the tagged objects slightly exceeds said minimum distance.

2. A method according to claim 1, further comprising the step of:

the person grasping with said one hand a handle of at least one of the tagged objects,

wherein the step of mounting an RFID;

tag transceiver on each tagged object includes mounting each tag transceiver near a handle on its respective tagged object.

3. An RFID interrogator apparatus having an adjustable two-way communication range so as to permit a person to individually interrogate the closest one of a plurality of nearby tagged objects, wherein each tagged object has a respective RFID tag transceiver attached thereto, comprising:

an RFHD interrogator transceiver characterized by a set of one or more performance parameters which control a reliable two-way communications range between the interrogator transceiver and any of the RFID tag transceivers;

an antenna which is connected to the interrogator transceiver and which is adapted for mounting on a person near one hand of the person, so that the person can reduce the distance between the antenna and a tag transceiver to a minimum distance by extending his hand toward the tag transceiver; and

a control logic circuit, connected to the interrogator transceiver, for adjusting at least one of said performance parameters so that the reliable two-way communications range between the interrogator transceiver and the transceiver of each of the tagged objects slightly exceeds said minimum distance.

4. An RFID system having an adjustable two-way communication range so as to permit a person to individually interrogate the closest one of a plurality of nearby tagged objects, comprising:

a plurality of tagged objects, wherein each tagged object includes a respective RFID tag transceiver attached thereto;

an RFID interrogator transceiver characterized by a set of one or more performance parameters which control a reliable two-way communications range between the interrogator transceiver and any of the RFID tag transceivers;

an antenna which is connected to the interrogator transceiver and which is adapted for mounting on a person near one hand of the person, so that the person can reduce the distance between the antenna and a tag transceiver to a minimum distance by extending his hand toward the tag transceiver; and

a control logic circuit, connected to the interrogator transceiver, for adjusting at least one of said performance parameters so that the reliable two-way communications range between the interrogator transceiver and the transceiver of each of the tagged objects slightly exceeds said minimum distance.

5. An RFID interrogator apparatus according to claim 4, wherein:

the RFID tag transceiver of each tagged object is mounted near a handle on its respective tagged object; and

said minimum distance is a distance between the antenna and the tag transceiver of one of the tagged objects when said person grasps the handle of said one tagged object.