System and Method for Radio Frequency Tag Group Select

Abstract

A system and method is disclosed for selecting certain subgroups of radio frequency (RF) tags for querying, communicating, and/or identifying by a base station. The base station sends commands to a group tags within a RF field of the base station. The tags use control logic to determine whether or not they meet certain criteria sent out by the commands. This may cause the tags to change state which either prevents or allows a given tag to participate in an identification process. In this way, a given subgroups of tags meeting certain criteria can be selected for querying, communicating, and/or identifying.

1 . A method of selecting subgroups of a group of radio frequency tags comprising the steps of: 
 a. sending a group select radio signal command from a base station to a plurality of radio frequency tags, the command defining certain selection conditions, the tags each having a radio frequency communications component for receiving the command and a tag memory with tag fields;    b. changing a state of one or more tags in the group of tags, the state change being from a READY state to a SELECTED state, the tags changing state being a selected subgroup of tags from the group of tags, and the selected tags having data in their respective tag memory that meets the selection conditions.    
     
     
         2 . The method of  claim 1 , where the selected tags send a tag identifier to the base station.  
     
     
         3 . The method of  claim 1 , where the selected tags change data in one or more tag fields of their respective memory.  
     
     
         4 . The method of  claim 1 , where steps a and b are repeated one or more times to create a ORed subgroup which includes the union of the tags of each of the subgroups.  
     
     
         5 . The method of  claim 2 , where the tags are queried to indicate that the selected subgroup has one or more members.  
     
     
         6 . The method of  claim 5 , where a flag is set if the selected subgroup has members, the flag being an alarm and the selection condition being that there was a security breach.  
     
     
         7 . The method according to  claim 1 , wherein 
 in step a. the command defining certain logical selection conditions; and    in step b. the tags changing state being a first selected subgroup of tags from the group of tags;    the method further comprises the steps of:    c. sending a group unselect radio signal command from a base station to a plurality of radio frequency tags, the command defining certain logical unselection conditions; and    d. changing a state of one or more tags in the first selected subgroup of tags, the state change being from the SELECTED state to the READY state, the remaining tags in the SELECTED state being a second selected subgroup of tags, the tags in the second selected subgroup having data in their respective tag memories that meet both the selection and unselection conditions.    
     
     
         8 . The method of  claim 7 , where steps c and d are repeated one or more times to create an ANDed subgroup which includes the tags in the intersection of each of the second selected subgroups.  
     
     
         9 . The method of  claim 7 , where the selection conditions are one or more of the logical comparisons including greater than, less than, equal, not equal, greater than or equal, and less than or equal.  
     
     
         10 . The method of  claim 9 , where the comparison is made between a data value sent from the base station and a tag value stored in the tag memory.  
     
     
         11 . The method of  claim 10 , where the tag value is a value obtained by masking in the tag.  
     
     
         12 . The method of  claim 7 , where the unselection conditions are one or more of the logical comparisons including greater than, less than, equal, not equal, greater than or equal, and less than or equal.  
     
     
         13 . The method of  claim 12 , where the comparison is made between a data value sent from the base station and a tag value stored in the tag memory.  
     
     
         14 . The method of  claim 13 , where the tag value is a value obtained by masking in the tag.  
     
     
         15 . A system for selecting subgroups of radio frequency tags from a group of tags, comprising: 
 a. a base station for communicating radio frequency commands to the tags, the commands comprising command type, function, tag memory address value, and command data;    b. a plurality of tags having radio frequency component for receiving the radio frequency commands from the base station and sending radio frequency information to the base station, a tag memory with a tag memory address and tag memory data, tag control logic, a tag compare function, and a tag state, whereby the command type sent by the base station causes the tag control logic to perform the function sent by the base station in the tag compare function to compare tag memory data located in the tag memory address specified by the tag memory address value with the command data, and if comparison conditions are met, the tag control logic causing the tag state to change.    
     
     
         16 . The system, as in  claim 15 , where the command type is a select command and the tag logic causes the tag to move from a READY state to a SELECTED state; or 
 where the command type is a unselect command and the tag logic causes the tag to move from a SELECTED state to a READY state.    
     
     
         17 . The system, as in  claim 15 , where the tags identify clothing.  
     
     
         18 . The system, as in  claim 16 , where the base station queries the tags in the SELECTED state.  
     
     
         19 . The system, as in  claim 18 , where an security alarm is enabled if there are any tags in the SELECTED state.  
     
     
         20 . A system for selecting a subset of slaves that satisfy a selection criterion, and causing the selected subset of slaves to participate in an identification and isolation process whereby slaves of the selected subset are successively identified and isolated from further participation in such identification and isolation process, said system comprising: 
 (a) a master unit for communicating a command containing a selection criterion to a plurality of slaves;    (b) each slave of said plurality of slaves being in one of three or more different possible conditions during the identification and isolation process;    (c) a memory in said each slave containing at least one information value for use in evaluation of a selection criterion;    (d) a receiving unit in said each slave for receiving the command containing the selection criterion from the master unit; and    (e) a processing unit in said each slave that processes the command containing the selection criterion from the master unit;    (f) the processing units of the slaves having a mode of operation such that a subgroup of slaves that have an information value that satisfies the selection criterion are moved from a first condition to a second condition for participation in an identification and isolation process; and    (g) the processing units of the subgroup of slaves in the second condition having a mode of operation whereby individual slaves of said subgroup can progress to a third condition during the identification and isolation process, with slaves that have progressed to the third condition, and have been identified, being isolated from further participation in the identification and isolation process that continues so as to identify and isolate other of the slaves in the second condition.    
     
     
         21 . A method for selecting a subset of slaves that satisfy at least one selection criterion during a selection process, and then identifying slaves of the selected subset, and causing identified slaves of the selected subset of slaves to be isolated from further participation in the identification process, said method comprising; 
 (a) storing at least one information value in each of a plurality of slaves for use in evaluating at least one selection criterion;    (b) representing at least one selection criterion in at least one selection criterion command;    (c) communicating the at least one selection criterion command to the plurality of slaves;    (d) processing the at least one selection criterion command at each of said plurality of slave and deeming certain of the slaves based on storage of the at least one information value to be selected as a result of the selection process;    (e) carrying out an identification process with respect to the certain slaves deemed selected as a result of the selection process; and    (f) causing slaves that are identified during the identification process of clause (e) to be isolated from responding further in the course of the identification process of clause (e).