Abstract:
A radio frequency identification (RFID) transponder may include a substrate and a device. The substrate may be in communication with a controller and an antenna, and the antenna is arranged to receive radio frequency signals. A first side surface of the substrate may include a capacitor. The device may be detachably coupled with the substrate via a conductive member positioned between the structure and the capacitor of the substrate, and the conductive member may be within a desired proximity of the capacitor. The structure may be attached to an attachment surface so that an attachment strength between the structure and the attachment surface may be greater than a force required to decouple the structure from the substrate. When the structure is decoupled from the substrate, the conductive member separates from the capacitor, disabling the transponder.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/956,763 filed Dec. 2, 2015, which in turn claims the benefit of U.S. Provisional Application No. 62/099,104, filed Dec. 31, 2014. The disclosure of the prior applications is hereby incorporated by reference herein in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to a radio frequency identification (RFID) tag and, more specifically, to a battery-assisted power (BAP) RFID tag with an anti-tamper assembly. cl BACKGROUND 
         [0003]    Vehicles can be automatically monitored with an electronic vehicle identification system, which is done with a wireless interface between a vehicle and a monitoring device. An electronic vehicle identification system is based on a RFID transponder, or tag, that is attached to a vehicle and a reader with an antenna for interrogating with the vehicle. 
         [0004]    A RFID transponder is used for providing remotely controllable identity information of the vehicle. With the user configurable memory in the RFID transponder, the information can be written and read remotely. A RFID transponder is commonly classified, in terms of the use they make of an internal power source, as: a passive RFID transponder which has no internal power source and uses the energy of the RF radiation transmitted by the reader; an active RFID transponder which comprises an internal power source that is used for both powering the transponder and for generating the RF energy required for transmitting a response radiation; and a battery-assisted RFID transponder (also referred to as a semi-active or a semi-passive transponder) which comprises an internal power source, where the energy of the response radiation is derived from the interrogation radiation provided by the reader and the transponder circuitry is powered by the internal power source. 
         [0005]    A battery-assisted passive (BAP) transponder has a small battery on board and is activated when in the presence of an RFID reader. The battery to powers the transponder&#39;s return reporting signal. Of course, a passive tag is cheaper and smaller because it has no battery; instead, the tag uses the radio energy transmitted by the reader. However, to operate a passive tag, it must be illuminated with a power level roughly a thousand times stronger than for signal transmission. That makes a difference in interference and in exposure to radiation. 
         [0006]    In the passive RFID transponder, the limitation is a reading distance while the RFID transponder needs to receive its operating power from a reader. In the active RFID transponder, the RFID transponder has a transmitter which requires more complex electronics for the functionality thus resulting in high cost and consumption of power compared to the battery-assisted RFID transponder and the passive RFID transponder. The energy required for battery-assisted RFID transponder and the passive RFID transponder to function is considerably less than for the active RFID transponder. 
         [0007]    In some applications, an RFID transponder is associated with a single vehicle. For example, a transponder attached to a vehicle has a code that identifies the vehicle and other data associated with the vehicle, such as the registered owner, the license plate number, and/or any other information about the vehicle. Users sometime attempt to remove the transponder from the vehicle and attach it to a different vehicle, despite such transfer being prohibited by the organization issuing the transponder. As such, some transponders may be provided with a mechanism whereby the transponder cannot be removed from the vehicle without permanently and irreparably destroying the transponder. This destruction creates undesired costs and inefficiency. It may be desirable to provide an RFID transponder with a tamper-proof assembly that temporarily disables the transponder if a user attempts to remove the transponder from the vehicle with which it is associated. 
       SUMMARY 
       [0008]    To address the above issues, a tamper-proof RFID transponder is provided. The transponder is attached to an attachment surface of, for example, a vehicle. The transponder includes a break-away structure that is detachably coupled with a housing of the transponder. If someone attempts to remove the transponder from the attachment surface, the break-away structure remains with the attachment surface and becomes decoupled from the housing. When the break-away structure is decoupled, a conductive foam member separates from a capacitor on a substrate contained in the housing, thereby creating a capacitance change of the capacitor. When the capacitance change exceeds a predetermined threshold, a microcontroller provided on the substrate is scrambled, thereby disabling the transponder. The microcontroller remains scrambled until reprogrammed, thus providing evidence of tampering but also permitting re-enablement of the transponder. 
         [0009]    In one embodiment, an RFID transponder includes a housing and a substrate contained in the housing. A microcontroller and an antenna are arranged on the substrate. The microcontroller communicates with an RFID unit, and the antenna receives and backscatters radio frequency interrogation radiation. A first side surface of the substrate includes a capacitor. A break-away structure is detachably coupled with the housing, and a conductive foam member is sandwiched between the break-away structure and the capacitor of the substrate. The conductive foam member is within a desired proximity of the capacitor. An adhesive member is configured to attach the break-away structure to an attachment surface. An attachment strength of the adhesive member with the break-away structure and the attachment surface is greater than a force required to decouple the break-away structure from the housing. When the break-away structure is decoupled from the housing, the conductive foam member separates from the capacitor and the transponder is disabled. 
         [0010]    In another embodiment, a radio frequency identification (RFID) transponder comprises a substrate and a break-away device. The substrate is in communication with a controller and an antenna, and the antenna is arranged to receive radio frequency signals. A first side surface of the substrate includes a capacitor. The break-away device may be detachably coupled with the substrate via a conductive member positioned between the break-away structure and the capacitor of the substrate, and the conductive member may be within a desired proximity of the capacitor. The break-away structure is attached to an attachment surface so that an attachment strength between the break-away structure and the attachment surface is greater than a force required to decouple the break-away structure from the substrate. When the break-away structure is decoupled from the substrate, the conductive member separates from the capacitor and the transponder is disabled. 
         [0011]    In another embodiment, a method of radio frequency identification (RFID) communications may include: providing a transponder comprising: a substrate, an antenna, and a break-away structure, wherein a first side surface of the substrate includes a capacitor; detachably coupling the break-away device with the substrate via a conductive member positioned between the break-away structure and the capacitor of the substrate, the break-away structure being attached to an attachment surface so that an attachment strength between the break-away structure and the attachment surface is greater than a force required to decouple the break-away structure from the substrate; decoupling the break-away structure from the substrate so that the conductive foam member moves away from the capacitor; and disabling the transponder is disabled in response to the decoupling the break-away structure from the substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The objects and features of the disclosure can be better understood with reference to the drawings described below, and the claims. The drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of embodiments of the disclosure. In the drawings, like numerals are used to indicate like parts throughout the various views. 
           [0013]      FIG. 1  illustrates an RFID system in accordance with the disclosure. 
           [0014]      FIG. 2  is an exploded view of an example of an RFID transponder having an anti-tamper assembly in accordance with the disclosure. 
           [0015]      FIG. 3  is an enlarged view of the break-away structure of  FIG. 2 . 
           [0016]      FIG. 4  is a cross-sectional view of the RFID transponder of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0017]    Various examples of the disclosure will now be described. The following description provides specific details for a thorough understanding and enabling description of these examples. One skilled in the art will understand, however, that the disclosure may be practiced without many of these details. Additionally, some well-known structures or functions may not be shown or described in detail, so as to avoid unnecessarily obscuring the relevant description. 
         [0018]    The terminology used in the description presented below is intended to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the disclosure. Certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section. 
         [0019]    Examples according to the disclosure may find ready applications in a setting where RFID tags are placed on vehicles. These applications may include, for example, paying tolls, parking, purchasing gas, and any other application. It should be understood that, while examples of the present disclosure are discussed herein with regard to a vehicle, the present disclosure may not be so limited and could be applied to various other applications. 
         [0020]      FIG. 1  illustrates an RFID system  100  including an RFID unit  104  and an RFID transponder  106 . The RFID unit  104  is configured to read from and/or write to transponders  106  within the range  112  of the RFID unit  104 . According to one embodiment, the RFID unit  104  includes a transceiver  114 , a read/write module  116 , a unique identifier  118  stored in memory, and an antenna. The RFID transponder  106  includes memory  108  where a code associated with the RFID transponder  106  is stored. The code of the RFID transponder  106  identifies the item it is attached thereto. For example, a transponder attached to a vehicle has a code that identifies the vehicle and other data associated with the vehicle, such as the registered owner, the license plate number, and/or any other information about the vehicle. The transponder code is capable of being modified to add or change the data therein. In one embodiment, a unique identifier may be added as a prefix to the code of the transponder by the RFID unit  104 . In another embodiment, the unique identifier does not modify the code but instead is saved as an additional code in the transponder. Regardless, when an RFID unit  104  queries the RFID transponder  106 , the RFID transponder  106  may transmit back to the RFID unit  104  both the code and the unique identifier. 
         [0021]    The antenna of the RFID unit  104  is designed to transmit a signal to a transponder which instructs the transponder to write the unique identifier to the transponder, such as a prefix to the previously-stored code. The transponders may be “passive” RFID tags, “active” RFID tags, or “battery assisted passive” (BAP) tags. Passive RFID tags are a type of transponder that does not contain their own power source or transmitter. When radio waves from the RFID writer reach the transponder&#39;s antenna, the energy is converted by the transponder&#39;s antenna into electricity that can power up the microcontroller in the tag (typically via inductive coupling). The passive RIFD tag is then able to receive and store the unique identifier to memory at the RFID tag by modulating the RFID reader&#39;s electromagnetic waves. “Active” RFID tags have their own power source and transmitter. The power source, usually a battery, is used to run the microcontroller&#39;s circuitry and to broadcast a signal to an RFID reader. Passive RFID tags do not have as great a range as active RFID tags, but it should be understood that either type of transponder may be employed in the present application. 
         [0022]    When the RFID transponder  106  is within the range  112  of the RFID unit  104 , the RFID unit  104  may receive a code stored in the memory  108  associated with the RFID transponder  106  is stored. It should be understood that the RFID unit  104  may be a RFID reader/writer that is configured to read from and write to transponders. 
         [0023]    Referring now to  FIG. 2 , the RFID transponder  106  may be, for example, a BAP RFID transponder. The transponder  106  may include a housing  230  ( FIG. 4 ) having a top portion  232  and a bottom portion  234 . According to various aspects, the top and bottom portions  232 ,  234  of the housing  230  can be constructed of rigid, non-flexible parts that create an enclosure around the RFID transponder. For example, the housing  230  can be constructed from plastics or fiberglass materials, but can also be constructed of any material suitable for encapsulating resonant components at ultra-high frequencies. 
         [0024]    The housing  230  contains a printed circuit board  236 . The printed circuit board  236  may be a substrate, which for example is rigid or flexible and on which a microcontroller  237 , a battery, and an antenna are constructed. In some aspects, the printed circuit board  236  can be replaced with a PET plastic film with an adhered conductive metal layer. It should be understood that the substrate may include a microcontroller  237 , which has both an analogue part for modifying the impedance matching of an antenna circuitry and a digital part for holding the logical functions and memory which enable RFID functionalities according to the air-interface standards that are used in the RFID transponder  106 . The substrate may also include a battery, for example, a  3  volt battery, attached to the microcontroller  237  by means of conductive path, such as a conductive wire between the battery and the microcontroller  237 , conductive glue, or mechanical bond between the microcontroller  237  and the battery. The battery may be, for example, a thin-film battery with thickness less to  1  millimeter. The printed circuit board  236  may include an antenna arranged to receive/backscatter radio frequency interrogation radiation from/to the RFID unit  104 . 
         [0025]    As shown in  FIG. 2 , the printed circuit board  236  includes a capacitive member, or capacitor,  238  implemented on the printed circuit board  236 . The microcontroller  237  is programmed to periodically probe the capacitor  238  to measure the capacitance and determine whether the capacitance of the capacitor  238  has changed. If the microcontroller  237  determines that the capacitor  238  experiences a change of capacitance that exceeds a predetermined threshold, the microcontroller  237  disables the transponder  106 . 
         [0026]    The transponder  106  includes a break-away structure  240  coupleable with the bottom portion  234  of the housing  230 . For example, as shown in  FIG. 3 , the break-away structure  240  may have a raised center region  242  and a peripheral flange  244 . The raised center portion  242  is sized and arranged to be received by the cutout region  250  of the bottom portion  234  of the housing  230 . The center portion  242  may include a plurality of tabs  243  spaced about its periphery. The tabs  243  may extend outward of the periphery of the center portion  242   
         [0027]    When the top and bottom portions  232 ,  234  of the housing  230  are assembled to contain the printed circuit board  236 , the raised centered portion  242  of the break-away structure  240  slightly enters the cutout region  250  such that the tabs  243  extending from the surface of the cutout region  250  can engage an inner surface  245  of the bottom portion  234  of the housing  230  thus removably coupling the break-away structure  240  to the housing  230 . When the break-away structure  240  is coupled with the housing  230 , a surface  246  of the raised center portion  242  faces the printed circuit board  236  within the housing  230 , while the peripheral flange  244  remains outside the bottom portion  232  of the housing  230 . As illustrated in  FIG. 3 , the surface  246  of the raised center portion  242  includes a raised platform  248 . 
         [0028]    Referring again to  FIG. 2 , the transponder  106  includes a first conductive foam member  252  and a second conductive foam member  254 . As illustrated in  FIG. 4 , when the break-away structure  240  is coupled with the bottom portion  234  of the housing  230 , the first conductive foam member  252  is positioned between the top portion  232  of the housing  230  and the capacitor  238  on a first side  233  of the printed circuit board  236  facing the top portion  232  of the housing  230 . The second conductive foam member  254  is positioned between the raised platform  248  and the capacitor  238  on a second side  235  of the printed circuit board  236  facing the bottom portion  234  of the housing  230 . 
         [0029]    As discussed above, the capacitor  238  is electrically incorporated into the printed circuit board  236  such that the microcontroller  237  can enable and disable the printed circuit board  236 , and thus the transponder  106 , depending on the capacitance of the capacitor  238 . For example, when the first and second conductive foam members  252 ,  254  are within a desired distance relative to the capacitor  238  on the first and second sides of the printed circuit board  236 , the capacitance of the capacitor  238  remains substantially unchanged. The microcontroller  237  thus determines that the capacitor  238  has not experienced a capacitance change that exceeds the predetermined threshold. As a result, the printed circuit board  236  is enabled and the transponder  106  is operable. However, when either one or both of the first and second conductive foam members  252 ,  254  are moved beyond the desired distance relative to the capacitor  238  on the first and/or second side of the printed circuit board  236 , the capacitance of the capacitor  238  changes. If the microcontroller  237  then determines that the capacitor  238  has experienced a capacitance change that exceeds the predetermined threshold, the microcontroller  237  disables the printed circuit board  236  and the transponder  106  is inoperable. It should be understood that the printed circuit board  236  may be “scrambled” when either one or both of the first and second conductive foam members  252 ,  254  is moved a sufficient distance away from the capacitor  238  such that a capacitance change exceeds the predetermined threshold. The printed circuit board  236  may remain scrambled until it is reprogrammed Thus, even if both the first and second conductive foam members  252 ,  254  are returned to a position closer to the capacitor  238  (or to their original positions), the printed circuit board  236  is not re-enabled and the transponder  106  remains inoperable. In one embodiment, to disable the transponder, power may be removed from the transponder or one or more other components from the transponder may be disconnected. In this regard, the transponder would effectively be disabled. 
         [0030]    The RFID transponder  106  includes an adhesive member  260  for coupling the transponder  106  to an attachment surface  290 . The attachment surface  290  may be, for example, a windshield, dashboard, or other surface of a vehicle. In some aspects, the adhesive member  260  may be a double-sided tape such as, for example, very high bond (VHB) or ultra high bond (UHB) double-sided tape. The bonding strength of the adhesive member  260  should be selected to provide a substantially permanent connection between the transponder  106  and the attachment surface  290 . As shown in  FIGS. 1 and 4 , the adhesive member  260  may be sized and arranged to couple the break-away structure  240  of the transponder with the attachment surface  290 . The bonding strength of the adhesive member  260  should be sufficient to keep the break-away structure  240  coupled with the attachment surface  290  even when a force is applied to the housing  230  of the transponder that causes the bottom portion  234  of the housing  230  to become decoupled from the break-away structure  240 . Thus, if a force is applied to the transponder  106  in an attempt to remove the transponder  106  from the attachment surface  290 , the force will cause the bottom portion  234  of the housing  230  to become decoupled from the break-away structure  240  while the adhesive member  260  will maintain attachment between the break-away structure  240  and the attachment surface  290 . When the bottom portion  234  of the housing  230  is decoupled from the break-away structure  240 , the second conductive foam member  254  moves away from the capacitor  238  on the second side of the printed circuit board  236  that faces the bottom portion  234  of the housing  230 . The movement of the second conductive foam member  254  away from the capacitor  238  on the second side of the printed circuit board  236  will result in a capacitance change that exceeds the predetermined threshold, and the printed circuit board  236  is disabled and the transponder  106  is inoperable. The printed circuit board  236  may also be “scrambled” when the capacitance change exceeds the predetermined threshold. The printed circuit board  236  may remain scrambled until it is reprogrammed 
         [0031]    In some aspects, the break-away structure  240  may be configured as a circular shape, and the second conductive foam member  254  may be positioned off-center on the break-away structure  240  such that the break-away structure  240  must be correctly rotationally aligned relative to the printed circuit board  236  in order to sandwich the second conductive foam member  254  between the raised platform  248  and the capacitor  238  on the second side of the printed circuit board  236  facing the bottom portion  234  of the housing  230 . This break-away structure  240  and the bottom portion  234  of the housing  230  may be provided with alignment markers, as would be understood by persons skilled in the art, in order to ensure proper alignment. The rotational alignment provides another mechanism for preventing tampering with the transponder  106 . For example, if housing  230  is rotated relative to the break-away structure  240 , which is fixedly attached to the attachment surface  290 , the second conductive foam member  254  may be moved a distance away from the capacitor  238  on the second side of the printed circuit board  236  causing a capacitance change that exceeds the predetermined threshold, and the printed circuit board  236  is disabled and the transponder  106  is inoperable. The printed circuit board  236  may also be “scrambled” when the capacitance change exceeds the predetermined threshold. The printed circuit board  236  may remain scrambled until it is reprogrammed 
         [0032]    According to some aspects, the break-away structure  24  may include a tamper tab  270 . When the top and bottom portions  232 ,  234  of the housing  230  are assembled, the tamper tab  270  extends through the opening  250  in the bottom portion  234  and cooperates with a corresponding through hole  272  in the printed circuit board  236 . Thus, if someone tries to twist the transponder  106  in an attempt to remove the transponder  106  from the attachment surface  290 , the tamper tab  270  breaks and the top and bottom portions  232 ,  234  of the housing  230  separate. As a result, one or both of the conductive foam members  242 ,  254  move away from the capacitor  238 , thereby creating a capacitive change that exceeds the predetermined threshold. The printed circuit board  236  is then disabled and the transponder  106  is inoperable. The printed circuit board  236  may also be “scrambled” when the capacitance change exceeds the predetermined threshold. The printed circuit board  236  may remain scrambled until it is reprogrammed 
         [0033]    Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise,” “comprising,” and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to.” As used herein, the terms “connected,” “coupled,” or any variant thereof, means any connection or coupling, either direct or indirect, between two or more elements; the coupling of connection between the elements can be physical, logical, or a combination thereof. Additionally, the words “herein,” “above,” “below,” and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word “or,” in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list. 
         [0034]    The above detailed description of embodiments of the disclosure is not intended to be exhaustive or to limit the disclosure to the precise form disclosed above. While specific embodiments of, and examples for, the disclosure are described above for illustrative purposes, various equivalent modifications are possible within the scope of the disclosure, as those skilled in the relevant art will recognize. For example, while processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified to provide alternative or sub-combinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times. Further any specific numbers noted herein are only examples: alternative implementations may employ differing values or ranges. 
         [0035]    The teachings of the disclosure provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments. 
         [0036]    Any patents and applications and other references noted above, including any that may be listed in accompanying filing papers, are incorporated herein by reference. Aspects of the disclosure can be modified, if necessary, to employ the systems, functions, and concepts of the various references described above to provide yet further embodiments of the disclosure. 
         [0037]    These and other changes can be made to the disclosure in light of the above Detailed Description. While the above description describes certain embodiments of the disclosure, and describes the best mode contemplated, no matter how detailed the above appears in text, the disclosure can be practiced in many ways. Details of the system may vary considerably in its implementation details, while still being encompassed by the disclosure disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the disclosure should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the disclosure with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the disclosure to the specific embodiments disclosed in the specification, unless the above Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the disclosure encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the disclosure under the claims. 
         [0038]    While certain aspects of the disclosure are presented below in certain claim forms, the inventors contemplate the various aspects of the disclosure in any number of claim forms. Accordingly, the inventors reserve the right to add additional claims after filing the application to pursue such additional claim forms for other aspects of the disclosure.