Abstract:
If the frequency of the electric waves used at a pre-designated inspection site is known frequency, the antenna seal connected to a base antenna is peeled off, in part or entirety. Thus, the resonance frequency is easily and correctly adjusted to the frequency known.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2006-23077, filed on 31 Jan., 2006 and No. 2006-338491, filed on 15 Dec. 2006, the entire contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a Wireless Tag that can cope with the situation where the communication electric waves differ in frequency from place to place, and a method of reading data from the Wireless Tag. 
   2. Description of the Related Art 
   In recent years, Wireless Tags, each storing an ID, have come into use. The Wireless Tag has a memory area in and from which the ID and any desired data can be written and read by wireless, without setting the tag into contact with a data write/read device. For example, Wireless Tags using the UHF-band electric waves have come into use in international physical distribution, such as international mail, international freight, and baggage inspection at international airports. 
   However, the frequency at which data is written into and read from Wireless Tags differs from area to area. For example, the frequency used in Europe ranges from 866 to 870 MHz, the frequency used in the United States ranges from 902 to 928 MHz, and the frequency used in Japan ranges from 950 to 956 MHz. 
   Consequently, the data written into a Wireless Tag in, for example, Europe cannot be read at all. If the data is read in Japan, it will be incorrect, due to the low data-reading accuracy. This raises a problem. 
   To solve the problem, the resonance frequency allocated to the antenna of the Wireless Tag may be adjusted. More precisely, a dielectric member may be attached to the antenna, or the dielectric seal already adhered to the antenna is peeled off (refer to Jpn. Pat. Appln. Laid-Open Publication No. 2005-101706). 
   In the method of attaching a dielectric member to the antenna, however, an error may be made in the position or size of the dielectric member attached. Inevitably, it is difficult to adjust the resonance frequency with high accuracy. The method of peeling off the dielectric seal cannot achieve good results if the frequency of the electric waves greatly differs from area to area, as in the inspection of international cargo. This is because this method is to adjust the resonance frequency minutely if the data cannot be correctly read from the Wireless Tag. The method peeling off the dielectric seal can indeed lower the resonance frequency, but it cannot cope with the case where the resonance frequency should be raised. Further, in this method it is necessary to determine an appropriate amount in which to peel off the dielectric seal from the antenna. 
   BRIEF SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a Wireless Tag whose resonance frequency can be adjusted easily and accurately. 
   In an aspect of the present invention, there is provided a Wireless Tag that includes an antenna configured to transmit and receive electric waves. The antenna has a base antenna unit and an antenna seal. The antenna seal is connected to the base antenna unit, has instructions for adjusting a resonance frequency of the antenna to a known frequency of electric waves used, and is configured to be peeled off. The antenna seal can be peeled off in part or entirety in accordance with the instructions. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a plan view showing a Wireless Tag according to a first embodiment, which remains in the initial state; 
       FIG. 1B  is a plan view showing the Wireless Tag of  FIG. 1A , which is being used in a certain manner; 
       FIG. 1C  is a plan view showing the Wireless Tag being used in another manner; 
       FIG. 2  is a plan view showing a modification of the Wireless Tag shown in  FIGS. 1A to 1C ; 
       FIG. 3  is a plan view showing a Wireless Tag according to a second embodiment, which remains in the initial state; 
       FIG. 4  is a diagram explaining how to peel a dielectric seal off; and 
       FIG. 5  is a plan view showing another modification of the Wireless Tag shown in  FIGS. 1A to 1C . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus and methods of the present invention. 
   Wireless Tags according to an embodiment of the present invention will be described in detail, with reference to the accompanying drawings. 
     FIG. 1A  is a plan view showing a Wireless Tag according to a first embodiment, which remains in the initial state. The Wireless Tag  10  has a base  12 , an IC chip (memory chip)  14 , a base antenna  16 , and antenna seals  18 . The IC chip  14  is embedded in the base  12 . The base antenna  16  is provided on one surface of the base  12 . The antenna seals  18  are bonded to the surface of the base  12  and connected to the base antenna  16 . The base antenna  16  is connected to the IC chip  14 . The base antenna  16  and the antenna seals  18  constitute an antenna  20 . 
   The Wireless Tag  10  further has various circuits (not shown). The circuits are: a rectifier circuit, a receiver circuit, a transmitter circuit, a power-supply circuit, and a control circuit. The rectifier circuit rectifies the AC current generated at the antenna  20 . The receiver circuit demodulates any signals it has received. The transmitter circuit modulates response signals and transmits them to a reader-writer. The power-supply circuit applies a DC voltage to the other circuits of the Wireless Tag  10 . The control circuit controls the other circuits of the tag  10 . 
   The antenna seal  18  is composed of a flexible seal substrate and an antenna pattern each. The substrate is made of resin. The antenna pattern is provided on the substrate and made of conductive material such as metal. The antenna pattern has perforations  22   a  and  22   b . The perforations  22   a  and  22   b  divide the antenna pattern into three regions  24   a ,  24   b  and  24   c , which are, nonetheless, electrically connected to each other. The three regions  24   a ,  24   b  and  24   c  should preferably have different colors so that they may better be distinguished than otherwise. 
   The antenna seals  18  are bonded to the end parts of the base antenna  16 , respectively. Therefore, they make the antenna  20  symmetrical in the lengthwise direction as will be described later, when any two corresponding regions are peeled off, respectively, from the end parts of the base antenna  16 . 
   The abbreviation “JP” is printed on each region  24   a , indicating that this region corresponds to the frequency band of 950 to 956 MHz at which data can be read and written, by wireless, from and into the Wireless Tag  10  in Japan. Similarly, the abbreviation “US” is printed on each region  24   b , indicating that this region corresponds to the frequency band of 902 to 928 MHz at which data can be read and written, by wireless, from and into the Wireless Tag  10  in the United States. The abbreviation “EU” is printed on each region  24   c , indicating that this region corresponds to the frequency band of 866 to 870 MHz at which data can be read and written, by wireless, from and into the Wireless Tag  10  in the members of the European Unit(not necessarily all members). 
   Hence, while the Wireless Tag  10  remains in the state shown in  FIG. 1A , the antenna  20  of the Wireless Tag  10  is allocated to the resonance frequency at which data can be read and written, by wireless, from and into the tag  10  in the members of the European Union. 
   The Wireless Tag  10  is suitable for use in the case where the frequency at which data is read and written by wireless from and into the tag  10  gradually increases as the load is transported from an area to another. Assume that the Wireless Tag  10  is attached to a load transported from a European Unit member to the United States, and thence to Japan. First, in the European Union member, the data about the load is written into the Wireless Tag  10 , and the tag  10  is attached to the load in the state shown in  FIG. 1A . 
   Next, the load arrives at the United States. In the United States, it is practically impossible to read data by wireless from the Wireless Tag  10  that assumes the state shown in  FIG. 1A . To read the data, the person who has received the load in the United States peels off the two regions  24   c , along the perforations  22   b . Those parts of the base antenna  16 , which lie under the regions  24   c , are peeled off, too. As a result, the Wireless Tag  10  changes in configuration as is illustrated in  FIG. 1B . As a result, the resonance frequency of the antenna  20  increases before peeling-off to change to the frequency used in the United States. Hence, the data can be read from the Wireless Tag  10  and new data can be written into the Wireless Tag  10 . 
   To avoid errors in peeling off the wireless IC seals  18 , it is desirable to print on the tag  10  arrows and phrases (e.g., PEAL, Direction for Peeling, or the like), indicating the direction in which to peel off the antenna seals  18 . If the base  12  has an area available for printing, “EU: [JP] [US] [EU],” “USA: [JP] [US],” “JPN [JP],” or the like may be printed, showing where the Wireless Tag  10  has been used and can be used. 
   Then, the load arrives at Japan. In Japan, it is practically impossible to read the data by wireless from the Wireless Tag  10  remaining in the state shown in  FIG. 1B . To read the data, the person who has received the load peels off the two regions  24   b , along the perforations  22   a . As a result, the Wireless Tag  10  changes in configuration as is illustrated in  FIG. 1C . As a result, the resonance frequency of the antenna  20  changes to the frequency used in Japan. Hence, the data can be read from the Wireless Tag  10  and new data can be written into the Wireless Tag  10 . 
   Thus, the Wireless Tag  10  is so configured that any person can easily peel off the prescribed regions of each antenna seal  18  in accordance with the marks or instructions printed on the tag  10 . Hence, the Wireless Tag  10  can well cope with the fact that the frequency at which the data is read and written by wireless from and into the tag  10  differs from area to area. Further, the amount in which the antenna seals  18  are peeled off is the same, no matter who peels them. Therefore, an antenna  20  from which a person has peeled off the antenna seals  18  has the same resonance frequency as another antenna  20  from which another person has peeled off the seals  18 . This can prevent troubles in the process of reading the data from the Wireless Tag  10 , because of the fact that the frequency used to read and write data from and into Wireless Tags differs from area to area. 
   The Wireless Tag  10  can of course be attached to a load to be transported from EU to US, a load to be transported from EU to JP, and a load to be transported from US to JP. 
     FIG. 2  is a plan view of a Wireless Tag  10 A that is a modification of the Wireless Tag  10  shown in  FIG. 1A to 1C . This Wireless Tag  10 A has a base antenna  16  that has the resonance frequency used in Japan. Two antenna seals  18   a  are bonded to the base antenna  16  and have a perforation  22   c  each. The perforation  22   c  divides the antenna seal  18   a  into two regions  24   d  and  24   e . “US,” “EU” and “JP” are printed on the region  28   d , region  28   e  and the base  12 , respectively. 
   This Wireless Tag  10 A is used in the same way as the Wireless Tag  10 . That is, in any member of the European Union, the Wireless Tag  10 A is used, having both antenna seals  18   a  bonded to the base  12 , each seal  18   a  having both regions  24   d  and  24   e . In the United States, it is used, having both antenna seals  18   a  bonded to the base  12 , each seal  18   a  having the region  24   d  only, with the region  24   e  peeled off. In Japan, it is used, with both regions  24   d  and  24   e  peeled off (that is, antenna seals  18   a  have been peeled off). 
     FIG. 3  is a plan view showing a Wireless Tag  30  according to the second embodiment of this invention, which remains in the initial state. This Wireless Tag  30  has dielectric seals  32  in place of such antenna seals  18   a  as used in the Wireless Tag  10  described above. That is, the Wireless Tag  30  comprises a base  12 , an IC chip  14  embedded in the base  12 , a base antenna  16  provided on one surface of the base  12 , and dielectric seals  32  bonded to the base antenna  16 . 
   The dielectric seals  32  increase the floating capacitance in the base antenna  16 . The antenna  34  therefore has a higher resonance frequency than the base antennas  16  in the state illustrated in  FIG. 3 . 
   The dielectric seals  32  are flexible substrates made of resin and fine particles of dielectric ceramic uniformly dispersed in the resin. Each dielectric seal  32  has slits  36   a  and  36   b . The slits  36   a  and  36   b  divide the dielectric seal  32  into three regions  38   a ,  38   b  and  39   c . The three regions  38   a ,  38   b  and  38   c  should preferably have different colors so that they may be better be distinguished than otherwise. 
   “EU,” “US” and “JP” are printed on the regions  38   a ,  38   b  and  38   c , respectively. These abbreviations mean the same areas as on the Wireless Tag  10  described above. 
   This Wireless Tag  30  is suitable for use in the case where the frequency at which data is read and written by wireless from and into it gradually deceases as the load is transported from an area to another. Assume that the Wireless Tag  30  is attached to a load transported from Japan to the United States, and thence to a European Union member. In this case, in Japan, the data about the load is written into the Wireless Tag  30 , and the tag  30  is attached to the load. Next, the load arrives at the United States. In the United States, the person who has received the load peels off the two regions  38   c , along the slits  36   b . At this point, only the dielectric seals are peeled off, and the base antenna  16  remains intact, as is illustrated in  FIG. 4 . As described above, the dielectric seals are substrates made of resin and fine particles of dielectric ceramic uniformly dispersed in the resin. Hence, the frequency increases due to “wave-compressing effect” as the dielectric seals approach the base antenna  16 . The wave-compressing effect decreases when the dielectric seals are peeled off. Therefore, the resonance frequency becomes lower. The resonance frequency of the antenna  34  of the Wireless Tag  30  therefore changes to the frequency of the electric waves used in the United States. When the load arrives at the European Union member, the person who has received the load peels off the two regions  38   b , along the slits  36   a . The resonance frequency of the antenna  34  of the Wireless Tag  30  therefore changes to the frequency of the electric waves used in the European Union member. 
   Needless to say, the Wireless Tag  30  can be modified in configuration in the same way as the Wireless Tag  10  is modified into the Wireless Tag  10 A. 
   Embodiments of the present invention have been described. The invention is not limited to the embodiments, nonetheless. Various changes can be made within the scope of the invention. More specifically, the antenna seals used to raise the resonance frequency and the dielectric seals used to lower the resonance frequency may be both bonded to the base  12 . Then, resonance frequency can be lowered if necessary after the antenna seals have been peeled and the resonance frequency has thereby been raised. Conversely, the resonance frequency can be raised if necessary after the dielectric seals have been peeled and the resonance frequency has thereby been lowered. 
   Moreover, the components of the embodiments described above may be combined in any appropriate manner in order to make various inventions. For example, some of the component of any embodiment may not be used. Moreover, the components of the different embodiments may be combined in any desired fashion. A specific example is such a Wireless Tag  40  as shown in  FIG. 5 . This tag  40  has an antenna seal  42  that has the same composition as the antenna seals  18  and bonded to only one end of the base antenna  16 , not to both ends of the base antenna  16  as the antenna seals  18  in the Wireless Tag  10 . This simplify the work of peeling off the antenna seal. This configuration can be applied to dielectric seals, if any, provided on the base antenna  16 . 
   Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit of the present invention. All such changes, modifications, and alterations should therefore be seen as within the scope of the present invention.