Patent Publication Number: US-2010123586-A1

Title: Rfid tag and manufacturing method of rfid tag

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation application of PCT/JP2007/063437, filed on Jul. 5, 2007. 
    
    
     TECHNICAL FIELD  
     The present invention relates to a RFID (Radio Frequency IDentification) tag that exchanges information with an external device in a non-contact manner and a manufacturing method of the RFID tag. 
     BACKGROUND ART  
     In recent years, there are proposed various types of RFID tag that exchanges information by radio waves in a non-contact manner with an external device represented by a reader-writer (see Japanese Laid-open Patent Publication Nos. 2000-311226, 2000-200332 and 2001-351082, for example). 
       FIG. 1  is a schematic cross-sectional diagram illustrating one example of an inner component member (inlay) constituting a RFID tag. 
     An inlay  10  for a RFID tag in  FIG. 1  is formed such that on an antenna base  11  made of, for example, PET film or the like that can bend, an antenna  12  made of a conductive pattern is formed and further a circuit chip  13  is mounted thereon. The circuit chip  13  incorporates a communication circuit for wireless communications with an external device via the antenna  12 . The circuit chip  13  is electrically connected to the antenna  12  by connection terminals  13   a  formed on the under surface of the circuit chip  13  by means of soldering or the like, and its surrounding is fixed to the antenna base  11  with an adhesive  14 . 
     A RFID tag has a structure in which the inlay  10  one example of which is illustrated in  FIG. 1  is enclosed inside. 
     A RFID tag exchanges information by radio waves in a non-contact manner so that when an antenna is brought too closely to metal, a reaching distance of radio waves is lowered or a malfunction occurs. Therefore, there is proposed a technique of providing a spacer to prevent an antenna from approaching metal too closely (see Japanese Laid-open Patent Publication No. 2005-309811, for example). 
     There is also proposed a RFID tag having an external shape of a belt (band), which is a type surrounding an article to be fixed (see Japanese Laid-open Patent Publication Nos. 01-259881, 2001-236476, 2001-173281, 2007-99484, and Japanese Patent No. 3883896, for example). 
     Alternatively, other than a belt, Japanese National Publication of International Patent Application No. 2001-516111, for example, proposes a RFID tag provided with a hook to which a string or a rubber band can be attached, for attaching the RFID tag to an article. 
     According to the above-described belt-type RFID tag, it is easy to attach the RFID tag to a column-shaped article like a cylinder or a tube-shaped article, which is convenient. 
     However, if the belt-type RFID tag is applied to, for example, a metal pillar or an article that contains a lot of water like a human being, especially in a case of a RFID tag utilizing radio waves in UHF band, there is a possibility that communications may be disabled due to effect of water or metal, or a communication available distance may be considerably shortened. In order to reduce effect of metal and water, there is known a structure in which a spacer is formed by a dielectric material such as plastic. However, it is difficult to accommodate to a column-shaped or a tube-shaped article by a hard spacer like this. 
     In view of the above circumstances, the present invention aims to provide a RFID tag having an external shape of belt, which can be applied to articles made of various kinds of materials. 
     DISCLOSURE OF INVENTION 
     According to an aspect of the invention, a RFID tag includes: 
     an inlay having an antenna and a circuit chip incorporating a communication circuit for wireless communications via the antenna; 
     an enclosure that encloses the inlay; 
     a flexible belt surrounding an article to attach the enclosure to the article; and 
     a spacer fixed to a surface of the enclosure on the article side, and deforming in response to deformation of the belt to maintain a spacing between the article and the enclosure. 
     The spacer may be a single continuous member having flexibility, or may be made up of plural space maintaining members that are disposed spaced apart in a longitudinal direction of the belt and that change shape as a whole by changing postures in response to deformation of the belt. 
     Either type of the above-described spacers can maintain a spacing effectively between an enclosure in which an inlay is enclosed and an article, by flexibly changing a shape or a posture of the spacers when the belt wraps around the article. 
     In the RFID tag of the present invention, the belt may be formed integrally with the enclosure, or may be formed separately from the enclosure and detachably attached to the enclosure. 
     If the belt is formed separately from the enclosure, for example, the enclosure may include a hole to let through the belt and the belt is attached to the enclosure by being inserted into the hole. 
     By forming a belt integrally, the number of parts is reduced, therefore cutting down on costs is achieved. On the other hand, by forming a belt separately, it is possible to attach the belt having a dimension in accordance with a dimension of an article, enabling flexible accommodation to articles having different dimensions. 
     In the RFID tag of the present invention, the inlay may include visible information recorded in a part of a surface of the inlay, and the enclosure may include a view window made of a material having light transmission characteristics to recognize the visible information. 
     By the structure that records a piece of visible information recognized with the eyes on an inlay, for example, by means of such as printing, and includes a view window made of a transparent material in the enclosure, a failure that the piece of visible information fades or disappears is prevented. 
     In the RFID tag of the present invention, if a spacer made of a continuous member having flexibility is provided as the above-described spacer, preferably the spacer is made of a foam material in which bubbles are dispersed. 
     Since a foam material includes air inside the spacer, and by the presence of air, it is possible to suppress an actual dielectric rate of the spacer, thereby improving an antenna gain without downsizing the antenna to the extent of unnecessary dimensions. 
     It is preferable that, if a spacer made of a continuous member having flexibility is provided, a dimension of the spacer is larger than that of the antenna with respect to a longitudinal direction of the belt and the spacer is fixed to a position covering the antenna. 
     By this, it is possible to maintain a spacing all the more securely between the antenna in the enclosure and the article. 
     It is also preferable that, if a spacer made of a continuous member having flexibility is provided, the spacer is formed such that rigid members to maintain a spacing between the enclosure and the article are dispersedly arranged in a flexible member. 
     By arranging rigid members dispersedly in a flexible member, it is possible to surely control a spacing between the enclosure and the article. 
     It is also preferable that, if a spacer made of a continuous member having flexibility is provided, the spacer includes an adhesion layer to adhere to an article, on a surface on the article side. 
     This prevents displacement of an attaching position of a RFID tag after the RFID tag is attached to an article, so that a secure attachment is enabled. 
     In the RFID tag of the present invention, it is preferable that, each of the plural space maintaining members forming the spacer includes a base section fixed to the enclosure and a pair of standing sections standing with respect to the enclosure and bifurcating from the base section into two branches in the longitudinal direction of the belt while widening a gap between the two branches. 
     If space maintaining members having the above-described shape including the base section and the pair of standing sections are employed, when the RFID tag is attached to an article, stability of the space maintaining members is enhanced and falling off of the space maintaining members is prevented. Additionally, employing the shape including the base section and the pair of standing sections does not impair accommodation to the shape of an attachment portion of an article. 
     According to another aspect of the invention, a first manufacturing method of a RFID tag, among manufacturing methods of a RFID tag of the present invention, includes: 
     making an inlay by mounting, on an antenna base on which an antenna is formed, a circuit chip incorporating a communication circuit for wireless communications via the antenna; 
     making a base including an inlay placement section in which the inlay is placed and a belt section extending from the inlay placement section and surrounding an article to be fixed to the article; 
     enclosing the inlay by placing the inlay in the inlay placement section of the base, further placing a cover such that the inlay is sandwiched between the cover and the base, and applying heat and pressure, so that an enclosure that encloses the inlay by the base and the cover is formed on the base; and 
     adhering a spacer that maintains a spacing between the article and the enclosure on a surface of the enclosure on the article side. 
     According to the above-described first manufacturing method, an enclosure and a belt are integrally formed, and thus a RFID tag of the present invention is manufactured. 
     According to yet another aspect of the invention, a second manufacturing method of a RFID tag, among manufacturing methods of a RFID tag of the present invention, includes: 
     making an inlay by mounting, on an antenna base on which an antenna is formed, a circuit chip incorporating a communication circuit for wireless communications via the antenna; 
     making a base on which the inlay is placed; 
     enclosing the inlay by placing the inlay in the inlay placement section of the base, further placing a cover such that the inlay is sandwiched between the cover and the base, and applying heat and pressure, so that an enclosure that encloses the inlay by the base and the cover is formed on the base; 
     molding a belt surrounding an article to attach the enclosure to the article; 
     forming a hole to let through the belt in the enclosure; and 
     adhering a spacer that maintains a spacing between the article and the enclosure on a surface of the enclosure on the article side. 
     According to the above-described second manufacturing method, an enclosure and a belt are separately formed, and thus a RFID tag of the present invention is manufactured. 
     Both of the first and the second manufacturing methods may further include: 
     making a spacer in which rigid members are dispersedly arranged in a flexible material, by alternately laminating a sheet member made of a flexible material and plural line members made of a rigid material, which are arranged spaced apart on the sheet member, and by forming a block in which the line members are dispersedly arranged in the flexible material through application of heat and pressure, and then by cutting the block in a predetermined thickness, 
     wherein the adhering of a spacer adheres the spacer that is made in the making of a spacer. 
     For example, by further including the above-described making of a spacer, rigid members are dispersedly arranged in a flexible material, and thus a RFID tag of the present invention is manufactured. 
     The article and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic cross-sectional diagram illustrating one example of an internal composition member (inlay) constituting a RFID tag; 
         FIG. 2  illustrates a RFID tag of a first embodiment of the present invention; 
         FIG. 3  is a drawing for explaining dimensions of the RFID tag illustrated in  FIG. 2 ; 
         FIG. 4  is a drawing for explaining an attaching method of the RFID tag illustrated in  FIG. 2 ; 
         FIG. 5  is a drawing illustrating a spacing between metal and a RFID tag in UHF band using 953 MHz, and a communication distance of the RFID tag; 
         FIG. 6  is a drawing illustrating a spacing between water and a RFID tag in UHF band using 935 MHz, and a communication distance of the RFID tag; 
         FIG. 7  illustrates a RFID tag of a second embodiment of the present invention; 
         FIG. 8  illustrates a RFID tag of a third embodiment of the present invention; 
         FIG. 9  illustrates a state in which the RFID tag illustrated in  FIG. 6  surrounds an article; 
         FIG. 10  illustrates a RFID tag of a fourth embodiment of the present invention; 
         FIG. 11  illustrates a state in which the RFID tag illustrated in  FIG. 10  surrounds an article; 
         FIG. 12  illustrates a RFID tag of a fifth embodiment of the present invention; 
         FIG. 13  illustrates a RFID tag of a sixth embodiment of the present invention; 
         FIG. 14  illustrates a RFID tag of a seventh embodiment of the present invention; 
         FIG. 15  illustrates a state in which the RFID tag illustrated in  FIG. 14  surrounds an article; 
         FIG. 16  illustrates a state in which the RFID tag of the eighth embodiment surrounds an article; 
         FIG. 17  is a flowchart illustrating one embodiment of a manufacturing method of a RFID tag of the present invention; 
         FIG. 18  is a drawing for explaining a step of making an inlay; 
         FIG. 19  is a drawing for explaining a step of making a base; 
         FIG. 20  is a drawing for explaining a step of enclosing an inlay; 
         FIG. 21  illustrates a shape after thermo-compression bonding; 
         FIG. 22  is a drawing for explaining a step of adhering a spacer; 
         FIG. 23  illustrates a completed RFID tag after a spacer is adhered; 
         FIG. 24  is a drawing for explaining a manufacturing method of a spacer; 
         FIG. 25  is a drawing for explaining a manufacturing method of a spacer; 
         FIG. 26  is a flowchart illustrating another example of a manufacturing method of a RFID tag of the present invention; 
         FIG. 27  is a drawing for explaining a step of making an inlay; 
         FIG. 28  is a drawing for explaining a step of making a base; 
         FIG. 29  is a drawing for explaining a step of enclosing an inlay; 
         FIG. 30  illustrates a shape after thermo-compression bonding; 
         FIG. 31  illustrates a belt; 
         FIG. 32  is a drawing for explaining a step of forming a hole and a step of adhering a spacer; and 
         FIG. 33  illustrates a completed RFID tag. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Embodiments of the present invention will be described with reference to the drawings. 
       FIG. 2  illustrates a RFID tag of a first embodiment of the present invention.  FIG. 2A  is a plan view, whereas  FIG. 2B  is a side view. 
     A RFID tag  100 A is composed of an inlay  10  having an antenna  12  and a circuit chip  13  as illustrated in  FIG. 1 ; an enclosure  20  for enclosing the inlay  10 ; a belt  30  that is integrally formed with the enclosure  20  and extends from the enclosure  20  in right and left directions in  FIG. 2 ; and a spacer  40  that is fixed (here, adhered) to a surface of the enclosure  20  on an article  90  side (see  FIG. 3 ). 
     The enclosure  20  and the belt  30  are made of a flexible material like rubber or plastic, and the inlay  10  is completely sealed in the enclosure  20 . In one end  30   a  of the belt  30 , notches  30   b  with bumps are formed, and on the other end  30 C of the belt  30 , a coupling section  30   d  having a through hole for letting through the one end  30   a  is formed. 
     The spacer  40  is a single continuous member and made of a material in the form of rubber that follows deformation. 
       FIG. 3  is a drawing for explaining dimensions of the RFID tag illustrated in  FIG. 2 . 
     Here, a size B of the spacer  40  in a longitudinal direction of the belt  30  (right and left directions in  FIG. 3 ) is larger than a size A of the antenna  12  constituting the inlay  10  in the longitudinal direction of the belt  30 . The spacer  40  is fixed to a position covering the antenna  12  with respect to the longitudinal direction of the belt  30 . 
     Since the RFID tag  100 A is provided with the spacer  40 , a spacing from the article  90  (see  FIG. 3 ) is securely maintained. 
       FIG. 4  is a drawing for explaining an attaching method of the RFID tag illustrated in  FIG. 2 . 
     As illustrated in part (A) of  FIG. 4 , the article  90  is wrapped around by the belt  30  while making the spacer  40  cover the article  90 , then the one end  30   a  is inserted into the through hole in the coupling section  30   d  (see  FIG. 2 ) to engage the notches  30   b  with bumps in the one end  30   a  with the through hole, and thus the RFID tag  100 A is attached to the article  90  as illustrated in part (B) of  FIG. 4 . 
     At this time, the spacer  40  is deformed by being sandwiched between the belt  30  and the article  90 , and maintains a spacing between the article  90  and the enclosure  20  (see  FIG. 2 ). 
     At this time, if the antenna  12  constituting the inlay  10  is placed near metal, since the metal reflects electromagnetic waves and cancels incident light, so that an electromagnetic field near the metal becomes considerably feeble. Alternatively, if water is present near the antenna  12 , since the water absorbs electromagnetic waves, so that an electromagnetic field near the water becomes considerably feeble as well. Therefore, if the article  90  is a metal pillar or a person&#39;s arm (high in water content), it is necessary to keep a distance from these by the spacer  40 . 
     A thickness necessary for the spacer  40  will be considered. 
     Here, it is assumed that the antenna  12  is a half-wave dipole antenna. If a gain and an impedance of the dipole antenna in a free space are designated as Ga, Za, respectively, whereas a gain and an impedance of the dipole antenna are designated as Ga′, Za′, respectively when there is nearby a metal plane extending infinitely, and an impedance of the circuit chip  13  is designated as Zt, then a power supplied to a RFID tag in a free space is obtained as follows. 
     
       
         
           
             
               
                 
                   
                     [ 
                     
                       Formula 
                        
                       
                           
                       
                        
                       1 
                     
                     ] 
                   
                    
                   
                       
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   P 
                   = 
                   
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                         ( 
                         
                           
                             
                               Re 
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                                 [ 
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                             - 
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                         ) 
                       
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
           
         
       
     
     The formula 1 calculates a power supplied to a RFID tag in a free space. 
     Subsequently, a power supplied to a RFID tag when metal is present is obtained as follows. 
     
       
         
           
             
               
                 
                   
                     [ 
                     
                       Formula 
                        
                       
                           
                       
                        
                       2 
                     
                     ] 
                   
                    
                   
                       
                   
                 
               
               
                 
                     
                 
               
             
             
               
                 
                   
                     P 
                     ′ 
                   
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                       Ga 
                       ′ 
                     
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                         ( 
                         
                           
                             
                               Re 
                                
                               
                                 [ 
                                 Zt 
                                 ] 
                               
                             
                             - 
                             
                               Za 
                               ′ 
                             
                           
                           
                             
                               Re 
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                                 [ 
                                 Zt 
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                             + 
                             
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                         ) 
                       
                       2 
                     
                   
                 
               
               
                 
                   ( 
                   2 
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     The formula 2 calculates a power supplied to a RFID tag when metal is present. 
     A communication distance is determined by a power supplied to a RFID tag, and a change amount R in a communication distance when metal is present nearby is proportionate to the square root of a power. 
     
       
         
           
             
               
                 
                   
                     [ 
                     
                       Formula 
                        
                       
                           
                       
                        
                       3 
                     
                     ] 
                   
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                   R 
                   = 
                   
                     
                       
                         P 
                         ′ 
                       
                       P 
                     
                   
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
     A change amount R is obtained by the above formula 3. 
       FIG. 5  is a drawing illustrating a spacing between metal and a RFID tag in UHF band using 953 MHz, and a communication distance of the RFID tag. 
     It is noted that when another frequency is used, a relationship is proportionate to a wavelength. 
     A relationship between a spacing of the metal and the RFID tag and a communication distance of the RFID tag, which is obtained by the above formulas presents gradual decrease in the communication distance up to 8 mm. However, a distance change rate becomes large in areas nearer than that. 
     That is, if a spacing between metal and a RFID tag is attained by only the thickness of a spacer, then in areas equal to or less than 8 mm, variations in the thickness of a spacer affect largely as variations in the communication distance and stable use is impaired. Therefore, using a spacer having a thickness of equal to or greater than 8 mm reduces influence of variations in the thickness of the spacer and is appropriate for attaching to metal. Alternatively, in practice, a spacer having a thickness of equal to or greater than 8 mm, in a thickness that is easily obtained (for example, 10 mm, 20 mm and so on) may be employed. 
       FIG. 6  is a drawing illustrating a spacing between water and a RFID tag in UHF band using 935 MHz, and a communication distance of the RFID tag, which is obtained in a similar manner. 
     Here, a half-wave dipole antenna is used and a communication distance is obtained by a similar calculation as that of metal, based on the assumption that a relative dielectric constant of water is 80.7; a dielectric loss tangent of water is 0.055; and a water tank has dimensions of 20 cm×20 cm×30 cm (depth). 
     A relationship between a spacing of the water and the RFID tag and a communication distance of the RFID tag, obtained by the above-description presents gradual decrease in the communication distance until when a spacer has a thickness of 18 mm. However, a distance change rate becomes large in areas thinner than that. 
     That is, if a spacing between water and a RFID tag is attained by only the thickness of a spacer, then in areas equal to or less than 18 mm, variations in the thickness of a spacer affects largely as variations in the communication distance and stable use is impaired. Therefore, using a spacer having a thickness of equal to or greater than 18 mm reduces influence of variations in the thickness of the spacer and is appropriate for attaching to an article that is presumably influenced by water. Alternatively, in practice, a spacer having a thickness of equal to or greater than 18 mm, in a thickness that is easily obtained (for example, 10 mm, 20 mm and so on) may be employed. 
     From the above consideration, in the RFID tag  100 A of the present embodiment and also in various kinds of embodiments to be described later, when a metal pillar is supposed as the article  90 , the thickness of the spacer  40  is defined to keep a spacing between the inlay  10  and the article  90  greater than or equal to 8 mm. Also, when an article that is high in water content like a person&#39;s arm is supposed as the article  90 , the thickness of the spacer  40  is defined to keep a spacing between the inlay  10  and the article  90  greater than or equal to 18 mm. 
     The above descriptions are a basic embodiment of the RFID tag of the present invention and in the following, various kinds of embodiments of the RFID tag of the present invention will be described. In each drawing illustrating each embodiment, identical components as those of the RFID tag  100 A in the first embodiment illustrated in  FIG. 2  are referred to by same numerals as in  FIG. 2 , and explanation will be made about differences. 
       FIG. 7  illustrates a RFID tag of a second embodiment of the present invention. 
     Only a spacer  41  is different in a RFID tag  100 B illustrated in  FIG. 7  as compared to the RFID tag illustrated in  FIG. 2 . The spacer  41  of the RFID tag  100 B illustrated in  FIG. 7  is a single continuous member as a whole, made of a foam material in which bubbles are dispersed, for example, rubber foam. 
     In general, a rubber material has a large dielectric loss and is apt to lose energy of electromagnetic waves, so that a communication distance is short. As such, here, the spacer  41  is made of a foam material such as rubber foam, for allowing air to be present inside the spacer  41  to suppress reduction in a communication distance. Although a rubber material has a dielectric rate of substantially 3 to 5 in general, it is possible to reduce an actual dielectric rate substantially to 2 by having air in a part. This improves an antenna gain without downsizing the antenna  12  to the extent of unnecessary dimensions. 
       FIG. 8  illustrates a RFID tag of a third embodiment of the present invention, and  FIG. 9  illustrates a state in which the RFID tag illustrated in  FIG. 8  surrounds an article. 
     Also in a RFID tag  100 C illustrated in  FIG. 8 , only a spacer  42  is different, as compared to the RFID tag  100 A illustrated in  FIG. 2 . The spacer  42  of the RFID tag  100 C illustrated in  FIG. 8  is a single continuous member having a structure in which rigid members  42   d  made of a material such as plastic are dispersedly arranged in a flexible member  42   a  made of a material such as rubber. As such, when the RFID tag  100 C surrounds the article  90 , by the rigid members  42   d  dispersedly arranged in the spacer  42 , a spacing between the antenna  12  constituting the inlay  10  and the article  90  is controlled irrespective of a wrapping strength of the belt  30 , so that a predetermined antenna characteristics can be obtained. 
       FIG. 10  illustrates a RFID tag of a fourth embodiment of the present invention, and  FIG. 11  illustrates a state in which the RFID tag illustrated in  FIG. 10  surrounds an article. 
     Also in a RFID tag  100 D illustrated in  FIG. 10 , only a spacer  43  is different, as compared to the RFID tag  100 A illustrated in  FIG. 2 . The spacer  43  of the RFID tag  100 D illustrated in  FIG. 10  includes an adhesive layer  43   b  for attaching to an article, on a surface of a base member  43   a  made of a flexible material such as rubber, on the article  90  side. 
     Therefore, when the RFID tag  100 D is once wrapped around the article  90 , the adhesive layer  43   b  adheres to the surface of the article  90 , preventing detachment or displacement of an attaching position of the RFID tag  100 D even if the belt  30  becomes loose more or less, so that a secure attachment is expected. 
       FIG. 12  illustrates a RFID tag of a fifth embodiment of the present invention.  FIG. 12A  is a plan view of the RFID tag and an inlay on the side, whereas  FIG. 12B  is a side view of the RFID tag. 
     An inlay  10 B constituting a RFID tag  100 E illustrated in  FIG. 12  further includes a piece of visible information (here, numbers “12345”) printed on its antenna base  11 , as compared to the inlay  10  explained with reference to  FIG. 1 . 
     An enclosure  20 B constituting the RFID tag  100 E illustrated in  FIG. 12  encloses the inlay  10 B on which the visible information is printed. The enclosure  20 B includes a view window  21  made of a transparent material for viewing a piece of visible information printed on the enclosed inlay  10 B. 
     If this structure is employed, a failure that a piece of visible information on the inlay  10 B fades or disappears is prevented. 
       FIG. 13  illustrates a RFID tag of a sixth embodiment of the present invention.  FIG. 13A  is a plan view, whereas  FIG. 13B  is a side view. In a RFID tag  100 F illustrated in  FIG. 13 , a belt  30 C is formed separately from an enclosure  20 C. In the enclosure  20 C, belt through holes  22  are formed and the belt  30 C is attached to the enclosure  20 C by being inserted into the belt through holes  22 . The RFID tag  100 F is attached to an article (illustration is omitted here) while the belt  30 C still being inserted in the belt through holes  22 . 
     In  FIG. 13 , although a spacer  44  has a different cross-sectional shape as compared to the spacer  40  of the RFID tag  100 A illustrated in  FIG. 2 , the spacer  44  is made of a single continuous member of a flexible material. 
     As illustrated in  FIG. 13 , if the belt  30 C is prepared separately from the enclosure  20 C, it is possible to use a same enclosure regardless of dimensions of an article, by preparing only belts having different lengths according to dimensions of an article. 
       FIG. 14  illustrates a RFID tag of a seventh embodiment of the present invention.  FIG. 15  illustrates a state in which the RFID tag illustrated in  FIG. 14  surrounds an article. 
     Although the above-described RFID tags  100 A to  100 F in various kinds of embodiments include a spacer made of a single continuous member, a RFID tag  100 G illustrated in  FIG. 14  is different from those RFID tags and includes a spacer  45  made up of plural space maintaining members  45   a  each arranged spaced apart in a longitudinal direction of the belt  30 . Each of the space maintaining members  45   a  is small enough compared to a size of the antenna  12  in a longitudinal direction of the belt, allowing attachment even to a column-shaped article. 
     The space maintaining members  45   a  constituting the spacer  45  are made of a rigid material such as plastic and change relative postures with respect to one another according to deformation of the belt  30  when the belt  30  is wrapped around the article  30  or the like, so that the spacer  45  deforms as a whole. Therefore, when the RFID tag  100 G surrounds the article  90  as illustrated in  FIG. 15 , each of the space maintaining members  45   a  constituting the spacer  45  takes a posture fitting to the deformation of the belt  30  and a surface shape of the article  90 . And thus the spacer  45  composed of the space maintaining members  45   a  maintains a spacing between the enclosure  20  and the article  90  to be a spacing controlled by a length of the space maintaining members  45   a.    
     As such, a spacer in the RFID tags of the present invention is not limited to a single continuous member, but may be composed of plural space maintaining members arranged in the longitudinal direction of the belt, like the one illustrated in  FIGS. 14 and 15 . 
       FIG. 16  illustrates a state in which the RFID tag of the eighth embodiment surrounds an article. 
     Here, a difference from the RFID tag  100 G of the seventh embodiment illustrated in  FIGS. 14 and 15  will be explained. 
     As compared to the RFID tag  100 G illustrated in  FIG. 14 , only a shape of a spacer  46  is different in a RFID tag  100 H illustrated in  FIG. 16 . 
     The spacer  46  of the RFID tag  100 H illustrated in  FIG. 16  is composed of space maintaining members  46   a  made of a rigid material such as plastic, arranged spaced apart in the longitudinal direction of the belt  30 , in a similar manner to the spacer  45  of the RFID tag  100 G illustrated in  FIGS. 14 and 15 . However, as compared to the spacer  45  of the RFID tag  100 G illustrated in  FIGS. 14 and 15 , a shape of the space maintaining members  46   a  is different. Each of the space maintaining members  46   a  has a shape including a base section  461  fixed to the enclosure  20  for enclosing an inlay (not illustrated here), and a pair of standing sections  462 ,  463  of the base section  461 , standing with respect to the enclosure  20  and bifurcating into two branches, from both ends in the longitudinal direction of the belt  30 , in the longitudinal direction of the belt  30  while widening a gap between the two branches. 
     In this way, since the spacer  46  of the RFID tag  100 H is composed of the plural space maintaining members  46   a  having a shape of open bifurcated branches, namely, a shape of trapezoid with legs, the space maintaining members have enhanced stability and thus resist falling off. Alternatively, when stability of the space maintaining members  46   a  is enhanced by enlarging a dimension of the space maintaining members  46   a  in the longitudinal direction of the belt, a capability of accommodating a surface shape of the article  90  is not lost and the space maintaining member  46   a  takes a flexible posture fitting to the surface shape of the article  90 . 
     Next, a manufacturing method of a RFID tag will be explained. 
       FIG. 17  is a flowchart illustrating one embodiment of a manufacturing method of a RFID tag of the present invention. 
     Here, a RFID tag that is one embodiment of the present invention is manufactured through the steps of making an inlay (step S 11 ), making a base (step S 12 ), enclosing an inlay (step S 13 ), and adhering a spacer (step S 14 ). 
     Hereafter, each step (step S 11  to S 14 ) will be explained. 
       FIG. 18  is a drawing for explaining a step of making an inlay (step S 11 ). 
     In this step, the inlay  10  is made by forming the antenna  12  on the antenna base  11 , and further mounting thereon the circuit chip  13  incorporating a communication circuit for wireless communications by using the antenna  12 . 
       FIG. 19  is a drawing for explaining a step of making a base (step S 12 ).  FIG. 19A  is a plan view of the base, whereas  FIG. 19B  is a side view of the base. 
     A base  50  is made by molding silicon rubber or the like and includes an inlay placement section  51  for placing the inlay  10  (see  FIG. 18 ) in a center and portions to be used as a belt (here, referred to as the belt  30 ) after completion of the RFID tag extend from both sides of the inlay placement section  51 . 
     In one end  30   a  of the belt  30 , notches  30   b  with bumps are formed, and on the other end  30   c  of the belt  30 , a coupling section  30   d  having a through hole for inserting the one end  30   a  is formed. 
       FIG. 20  is a drawing for explaining a step of enclosing an inlay. 
     On a heat and pressure application stage  201 , the base  50  illustrated in  FIG. 19  is placed, and the inlay  10  illustrated in  FIG. 18  is placed in the inlay placement section  51  (see  FIG. 19 ) of the base  50 . Further, a cover  60  made of a same material as the base  50 , separately formed, having a same shape as that of the inlay placement section  51  of the base  50  is placed thereon, and these are sandwiched by the heat and pressure application stage  201  and a heat and pressure application head  202  for thermo-compression bonding by the application of heat and pressure. 
       FIG. 21  illustrates a shape after thermo-compression bonding. 
     By the thermo-compression bonding in the step of enclosing an inlay (step S 13 ), the inlay placement section  51  of the base  5  and the cover  60  are thermally bonded and the enclosure  20  is formed with the inlay  10  completely shielded in the enclosure  20 . 
     Additionally, in  FIG. 21 , although a line is drawn between the base  50  and the cover  60  as if indicating that these are separate parts, this line is drawn for easier understanding and in actuality, these are completely bonded to be a seamless single state by the thermo-compression bonding. 
       FIG. 22  is a drawing for explaining a step of adhering a spacer (step S 14 ), and  FIG. 23  illustrates a completed RFID tag after the spacer is adhered. 
     By the thermo-compression bonding illustrated in  FIG. 20 , the RFID tag becomes a state as illustrated in  FIG. 21 , thereafter the separately formed spacer  40  is bonded to a base  50  by a double-faced adhesive  71 , and thus a RFID tag  100 I that is substantially similar to the RFID tag in  FIG. 2  is completed, as illustrated in  FIG. 23 . 
       FIGS. 24 ,  25  are drawings for explaining a manufacturing method of a spacer. 
     A manufacturing method illustrated in  FIGS. 17 to 23  is a manufacturing method based on the use of the spacer  40  made of a uniform material, for example, such as rubber. However, a spacer that is manufactured by an after-mentioned manufacturing method may be employed in place of the spacer  40  made of such a uniform material. 
       FIG. 24  illustrates a multilayer state in which a sheet member  72  made of a flexible material such as rubber and plural line members  73  made of a rigid material such as plastic that are arranged spaced apart on the sheet member  72  are stacked in layers. 
     The sheet member  72  and the plural line members  73  are stacked alternately in layers as illustrated in  FIG. 24 , and the entire lamination is sandwiched by the heat and pressure application stage  201  and the heat and pressure application head  202  for thermo-compression bonding to bond the sheet members  72  thermally, for example, as illustrated in  FIG. 20 . 
       FIG. 25  illustrates a block (B) that is formed by bonding base members thermally, and a sheet member (A) that is cut out from the block. 
     As illustrated in  FIG. 24 , when the sheet member  72  and the plural line members  73  are stacked alternately in layers and then the sheet members  72  are bonded thermally, then a block  75  is formed in which line members  73  made of a rigid material such as plastic are dispersedly arranged in two dimensions in a flexible member  74  made of rubber or the like, as illustrated in part (B) of  FIG. 25 . 
     From this block  75 , as illustrated in part (A) of  FIG. 25 , a sheet member is cut out in a thickness necessary for using as a spacer, and thus the sheet member  76  in which rigid members  77  are dispersedly arranged in the flexible member  74  is obtained. 
     By employing this sheet member  76 , a RFID tag that can control a spacing precisely between an enclosure and an article, which has been explained with reference to  FIGS. 8 ,  9  is completed. 
     In the manufacturing method of a RFID tag illustrated in  FIG. 17 , a spacer that is made in the step of making a spacer, which has been explained with reference to  FIGS. 24 ,  25  may be employed. 
       FIG. 26  is a flowchart illustrating another example of a manufacturing method of a RFID tag of the present invention. 
     Here, a RFID tag is manufactured through the steps of making an inlay (step S 21 ), making a base (step S 22 ), enclosing an inlay (step S 23 ), molding a belt (step S 24 ), forming a hole (step S 25 ), and adhering a spacer (step S 26 ). 
     Hereafter, each step (step S 21  to S 26 ) will be explained. 
       FIG. 27  is a drawing for explaining a step of making an inlay (step S 21 ). 
     In this step as well, the inlay  10  is made by forming the antenna  12  on the antenna base  11 , and further mounting the circuit chip  13  incorporating a communication circuit for wireless communications by using the antenna  12 , on the antenna base  11 . 
       FIG. 28  is a drawing for explaining a step of making a base (step S 22 ). 
     Here, silicon rubber or the like is molded to make a base  52  composed of only an inlay placement section for placing the inlay  10 . 
       FIG. 29  is a drawing for explaining a step of enclosing an inlay (step S 23 ). 
     The base  52  illustrated in  FIG. 28  is placed on the heat and pressure application stage  201 ; the inlay  10  illustrated in  FIG. 27  is placed on the base  52 ; and further, a cover  61  formed separately, having a same shape as that of the base  52 , made of a same material as the base  52  is placed thereon; and these are sandwiched by the heat and pressure application stage  201  and the heat and pressure application head  202  for thermo-compression bonding by the application of heat and pressure. 
       FIG. 30  illustrates a shape after the thermo-compression bonding. 
     By the thermo-compression bonding in the step of enclosing an inlay (step S 23 ), the base  52  and the cover  61  are thermally bonded and thus the enclosure  20 C is formed with the inlay  10  completely shielded in the enclosure  20 C. 
     Additionally, also in  FIG. 30 , similarly in  FIG. 21 , although a line is drawn between the base  52  and the cover  61  as if indicating that these are separate parts, this line is drawn for easier understanding and in actuality, these are completely bonded to be a seamless single state by the thermo-compression bonding. 
       FIG. 31A  is a plan view of a belt, whereas  FIG. 31B  is a side view of a belt. 
     Here, the belt  30 C is molded of nylon or silicon rubber and so on, separately from the enclosure  20 C illustrated in  FIG. 30 . 
     The belt  30 C has notches  30   b  in one end and a coupling section  30   d  on the other end, which is same as a belt that is integrally formed with the inlay placement section (see  FIG. 19 ). 
       FIG. 32  is a drawing for explaining a step of forming a hole (step S 25 ) and a step of adhering a spacer (step S 26 ). 
     In the enclosure  20 C that is formed as illustrated in  FIG. 30 , by the thermo-compression bonding illustrated in  FIG. 29 , the through holes  22  for letting through the belt  30 C illustrated in  FIG. 31  are formed, and furthermore, the spacer  44  is bonded to the enclosure  20 C by the double-faced adhesive  71 . 
       FIG. 33  illustrates a completed RFID tag.  FIG. 33A  is a plan view, whereas  FIG. 33B  is a side view. 
       FIG. 33  illustrates the enclosure  20 C in a state illustrated in  FIG. 32 , that is, a state in which the belt  30 C illustrated in  FIG. 31  is attached to the enclosure  20 C after the through holes  22  are formed and the spacer  44  is attached. 
     Through the above-described manufacturing steps, a RFID tag  100 J of a type providing a belt separately is completed, which is similar to the RFID tag in  FIG. 13 . 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiment(s) of the present invention(s) has (have) been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.