Method and apparatus to automatically search data carriers, such as RFID tags and machine-readable symbols

Abstract

A data carrier reader is capable of executing a number of different reading methods. A method for reading single RFID tags can store read data to a buffer for eventual transmission to a host, and can suppress redundant data. Still another method associates data read from an RFID tag with a particular object or item using a data coded in a machine-readable symbol. In a further method, the machine-readable symbol is automatically read when the RFID tag is within a predetermined proximity of the reader. In each method, the data carrier reader provides the user a consistent and intuitive output to identify the successful and unsuccessful operations such as reading an RFID tag or machine-readable symbol.

We claim:  
     
         1 . A method of automatically reading RFID tags, comprising: 
 reading a first tag identifier from a first RFID tag;    storing the first tag identifier to a memory;    reading a respective tag identifier from each of a number of RFID tags;    comparing the read tag identifiers to the tag identifiers stored in the memory; and    storing the tag identifiers in the memory that do not correspond the tag identifiers previously stored in the memory.    
     
     
         2 . The method of    claim 1   , further, comprising: 
 producing a human-perceptible indication when the read tag identifiers do not correspond to the tag identifiers previously stored in the memory.    
     
     
         3 . The method of    claim 1   , further, comprising: 
 producing a human-perceptible indication when the read tag identifiers correspond to the tag identifiers previously stored in the memory.    
     
     
         4 . The method of    claim 1   , further, comprising: 
 producing a first human-perceptible indication when the read tag identifiers correspond to the tag identifiers previously stored in the memory; and    producing a second human-perceptible indication, different from the first human-perceptible indication, when the read tag identifiers do not correspond to the tag identifiers previously stored in the memory.    
     
     
         5 . The method of    claim 1   , further comprising: 
 producing a first sound when the read tag identifiers correspond to the tag identifiers previously stored in the memory; and    producing a second sound, different from the first sound when the read tag identifiers do not correspond to the tag identifiers previously stored in the memory.    
     
     
         6 . The method of    claim 1   , further comprising: 
 transferring data from the RFID tag to a host computer when the read tag identifiers do not correspond to the tag identifiers previously stored in the memory.    
     
     
         7 . The method of    claim 1   , further comprising: 
 discontinuing reading the respective tag identifiers when the number of consecutive RFID tags having tag identifiers that do not correspond to the tag identifiers previously stored in the memory exceeds a determined maximum number.    
     
     
         8 . The method of    claim 1   , further comprising: 
 successively determining a maximum number based a number of tag identifiers stored in the memory; and    discontinuing reading the respective tag identifiers when the number of consecutive RFID tags having tag identifiers that do not correspond to the tag identifiers previously stored in the memory exceeds the determined maximum number.    
     
     
         9 . The method of    claim 1   , further comprising: 
 producing a human-perceptible indication having a characteristic that varies corresponding to the number of tag identifiers stored in the memory that do not correspond to the tag identifiers previously stored in the memory.    
     
     
         10 . A method of operating a data carrier reader, comprising: 
 reading a respective characteristic data strings from each of at least two RFID tags;    producing a first human-perceptible indication after each of the respective characteristic data strings from the RFID tags have been read;    comparing each of the read characteristic data strings to a set of identifiers stored in a memory to determine whether all of the RFID tags have been read; and    producing a second human-perceptible indication if all of the RFID tags have been read.    
     
     
         11 . The method of    claim 10   , further comprising: 
 storing at least an identifying portion of the characteristic data strings in a memory;    comparing at least a portion of each of the read characteristic data strings to the identifying portions stored in the memory to determine if the RFID tag has been previously read; and    producing a third human-perceptible indication after the number of successive repeatedly read RFID tags exceeds a maximum number of repeated reads.    
     
     
         12 . The method of    claim 10   , further comprising: 
 storing a first one of the characteristic data strings corresponding to a first one of the RFID tags to a buffer;    for each of the other RFID tags, successively, 
 reading the respective characteristic data string from the RFID tag;  
 transmitting at least a portion of the read characteristic data string to a host system if the read characteristic data string does not match any of the characteristic data strings previously stored in the buffer;  
 storing at least an identifying portion of the read characteristic data string to the buffer if the read characteristic data strings does not match any of the characteristic data strings previously stored in the buffer.  
   
     
     
         13 . The method of    claim 10   , further comprising: 
 receiving an interrogation command from a host system; and    powering a radio in response to the command from the host system.    
     
     
         14 . The method of    claim 10   , further comprising ceasing to power a radio after all of the RFID tags have been read.  
     
     
         15 . The method of    claim 10   , further comprising: 
 transmitting at least a portion of the first characteristic data string to a host system.    
     
     
         16 . A method of operating an RFID reader, comprising: 
 operating a radio in the RFID tag interrogator to write to an RFID tag; and    producing a first human-perceptible indication after writing to the RFID tag.    
     
     
         17 . The method of    claim 16   , further comprising: 
 receiving a confirmation signal from the RFID tag prior to producing the first human-perceptible indications.    
     
     
         18 . The method of    claim 16   , further comprising: 
 writing to a number of other RFID tags;    producing the first human-perceptible indication after writing to each of the other RFID tags; and    producing a second human-perceptible indication after writing to all of the RFID tags.    
     
     
         19 . The method of    claim 16   , further comprising: 
 writing to a number of other RFID tags;    producing the first human-perceptible indication after writing to each of the other RFID tags;    comparing a respective characteristic data string of each of the RFID tags to a set of identifiers stored in a memory to determine whether all of the RFID tags have been written; and    producing a second human-perceptible indication if all of the RFID tags have been written.    
     
     
         20 . The method of    claim 16   , further comprising: 
 writing to a number of other RFID tags;    producing the first human-perceptible indication after writing to each of the RFID tags;    comparing a respective characteristic data string of each of the RFID tags to a set of identifiers stored in a memory to determine if the RFID tag has been previously written; and    producing a second human-perceptible indication after the number of successive repeatedly written RFID tags exceeds a maximum number of repeated writes.    
     
     
         21 . The method of    claim 16   , further comprising: 
 ceasing to power the radio after writing to the RFID tag.    
     
     
         22 . A method of operating an RFID tag interrogator, comprising: 
 reading a respective characteristic data string from each of a number of RFID tags; and    producing a human-perceptible signal having a varying intensity, the intensity corresponding to a number of the read characteristic data strings meeting a defined criteria.    
     
     
         23 . The method of    claim 22   , further comprising: 
 determining the read characteristic data strings that meet the defined criteria including identifying the read characteristic data strings that do not match any of a number of characteristic data strings previously stored in memory.    
     
     
         24 . The method of    claim 22   , further comprising: 
 determining the read characteristic data strings that meet the defined criteria including identifying the read characteristic data strings match at least one of a number of characteristic data strings previously stored in memory.    
     
     
         25 . The method of    claim 22    wherein producing a human-perceptible signal having a varying intensity includes producing an audio output having a varying pitch.  
     
     
         26 . The method of    claim 22    wherein producing a human-perceptible signal having a varying intensity includes producing an audio output having a varying volume.  
     
     
         27 . The method of    claim 22    wherein producing a human-perceptible signal having a varying intensity includes varying a rate of an optical signal.  
     
     
         28 . The method of    claim 22    wherein producing a human-perceptible signal having a varying intensity includes producing an optical signal having a varying output power.  
     
     
         29 . The method of    claim 22   , further comprising: 
 determining a gain factor; and    varying the intensity corresponding to the gain factor and the read rate.    
     
     
         30 . A method of operating a data carrier reader, comprising: 
 reading data including a characteristic data string from an RFID tag;    reading data including a characteristic data string from a symbol; and    comparing at least a portion of the characteristic data string read from the RFID tag to at least a portion of the characteristic data string read from the symbol.    
     
     
         31 . The method of    claim 30   , further comprising: 
 producing a first human-perceptible indication if the portion of the characteristic data string read from the RFID tag matches the portion of the characteristic data string read from the symbol.    
     
     
         32 . The method of    claim 30   , further comprising: 
 producing a first human-perceptible indication if the portion of the characteristic data string read from the RFID tag matches the portion of the characteristic data string read from the symbol; and    producing a second human-perceptible indication, different from the first human-perceptible indication, if the portion of the characteristic data string read from the RFID tag does not match the portion of the characteristic data string read from the symbol.    
     
     
         33 . The method of    claim 30   , further comprising: 
 automatically turning on a symbol reader portion of the data carrier reader after reading data including a characteristic data string from an RFID tag.    
     
     
         34 . The method of    claim 30   , further comprising: 
 turning off a symbol reader portion of the data carrier reader if the portion of the characteristic data string read from the RFID tag matches the portion of the characteristic data string read from the symbol.    
     
     
         35 . The method of    claim 30   , further comprising: 
 transferring the data read from the RFID tag to a host if the portion of the characteristic data string read from the RFID tag matches the portion of the characteristic data string read from the symbol.    
     
     
         36 . The method of    claim 30   , further comprising: 
 modifying data stored ih a buffer according to the comparison.    
     
     
         37 . The method of    claim 30   , further comprising: 
 remove the data read from the RFID tag from a buffer if the portion of the characteristic data string read from the RFID tag matches the portion of the characteristic data string read from the symbol.    
     
     
         38 . The method of    claim 30   , further comprising: 
 store the data read from the RFID tag to a buffer if the portion of the characteristic data string read from the RFID tag matches the portion of the characteristic data string read from the symbol.    
     
     
         39 . A method of operating a data carrier reader, comprising: 
 receiving a plurality of characteristic data strings from each of a number of RFID tags, including at least one RFID tag of interest;    comparing at least a portion of each of the received characteristic data strings to at least one identifier stored in a buffer, the identifier corresponding to the RFID tag of interest;    producing a first human-perceptible indication in response to the number of received characteristic data strings that correspond to the at least one identifier; and    automatically operating a symbol reader when a rate of response corresponding to the at least one identifier exceeds a threshold value.    
     
     
         40 . The method of    claim 39   , further comprising: 
 producing a second human-perceptible indication in response to the number of received characteristic data strings that do not correspond to the at last one identifier.    
     
     
         41 . The method of    claim 39   , further comprising: 
 producing a second human-perceptible indication in response to the number of received characteristic data strings that do not correspond to the at last one identifier, wherein the first human-perceptible indication is a first sound and the second human-perceptible indication is a second sound, different from the first sound.    
     
     
         42 . The method of    claim 39   , further comprising: 
 determine a hit rate of response corresponding to a number of received characteristic data strings that correspond to the at least one identifier;    determine a miss rate of response corresponding to the number of received characteristic data strings that do not correspond to the at least one identifier; and    determine the threshold value from the hit rate of response and the miss rate of response.    
     
     
         43 . The method of    claim 39   , further comprising: 
 reading a symbol; and    comparing at least a portion of the read symbol to the at least one identifier stored in a buffer.    
     
     
         44 . The method of    claim 39   , further comprising: 
 reading a symbol;    comparing at least a portion of the read symbol to the at least one identifier stored in a buffer; and    automatically ceasing to power the symbol reader after reading the symbol.    
     
     
         45 . The method of    claim 39   , further comprising: 
 reading a symbol;    comparing at least a portion of the read symbol to the at least one identifier stored in a buffer; and    automatically transferring the characteristic data string read from the RFID tag of interest to a host if the at least a portion of the read symbol corresponds to the at least one identifier stored in a buffer.    
     
     
         46 . A method of operating a data carrier reader, comprising: 
 receiving a plurality of responses from a number of RFID tags including at least one RFID tag of interest; and    automatically operating a symbol reader when a rate of the responses from the RFID tag of interest exceeds a threshold rate of response.    
     
     
         47 . The method of    claim 46   , further comprising: 
 producing a first human-perceptible indication corresponding to a number of the responses received from the RFID tag of interest.    
     
     
         48 . The method of    claim 46   , further comprising: 
 producing a first human-perceptible indication corresponding to a number of the responses received from the RFID tag of interest; and    producing a second human-perceptible indication in response to a number of the responses received from the RFID tags other than the RFID tag of interest.    
     
     
         49 . The method of    claim 46   , further comprising: 
 determining the threshold rate of response from the ratio of the responses of the RFID tags other than the RFID tag of interest and the responses of the RFID tag of interest.    
     
     
         50 . The method of    claim 46   , further comprising: 
 reading a symbol; and    comparing at least a portion of the read symbol to at least a portion of at least one of the plurality of responses.    
     
     
         51 . The method of    claim 46   , further comprising: 
 reading a symbol;    comparing at least a portion of the read symbol to at least a portion of at least one of the plurality of responses; and    automatically ceasing to power the symbol reader after reading the symbol.    
     
     
         52 . The method of    claim 46   , further comprising: 
 reading a symbol;    comparing at least a portion of the read symbol to at least a portion of at least one of the plurality of responses; and    automatically transferring at least a portion of the response received from the RFID tag of interest to a host if the at least a portion of the read symbol corresponds to the at least a portion of the at least one of the plurality of responses.    
     
     
         53 . A method of automatically reading RFID tags, comprising: 
 receiving a plurality of characteristic data strings from each of a number of RFID tags, including at least one RFID tag of interest;    producing a first human-perceptible indication having an intensity corresponding to a rate of receiving the characteristic data strings from the RFID tag of interest.    
     
     
         54 . The method of    claim 53   , further comprising: 
 comparing at least a portion of each of the received characteristic data strings to at least one identifier stored in a buffer, the identifier identifying the RFID tag of interest.    
     
     
         55 . The method of    claim 53    wherein producing a human-perceptible signal includes producing an audio output having a pitch corresponding to the rate of receiving the characteristic data strings from the RFID tag of interest.  
     
     
         56 . The method of    claim 53    wherein producing a human-perceptible signal includes producing an audio output having a volume corresponding to the rate of receiving the characteristic data strings from the RFID tag of interest.  
     
     
         57 . The method of    claim 53    wherein producing a human-perceptible signal includes producing an optical signal having a rate corresponding to the rate of receiving the characteristic data strings from the RFID tag of interest.  
     
     
         58 . The method of    claim 53    wherein producing a human-perceptible signal includes producing an optical signal having an output power corresponding to the rate of receiving the characteristic data strings from the RFID tag of interest.  
     
     
         59 . The method of    claim 53   , further comprising: 
 determining a gain factor; and    adjusting the intensity of the first human-perceptible indication by the gain factor.    
     
     
         60 . The method of    claim 53   , further comprising: 
 determining a gain factor based on a hit rate corresponding to the rate of receiving the characteristic data strings from the RFID tag of interest, and a miss rate corresponding to the rate of receiving the characteristic data strings from the RFID tags other than the RFID tag interest; and    adjusting the intensity of the first human-perceptible indication by the gain factor.