Abstract:
The present invention teaches a tamper-proof electronic bolt seal which contains a bolt assembly and a seal body. The gist of the present invention lies in the bolt assembly which contains a casing, and a circuit board elastically suspended inside the casing. When a burglar grinds a bolt head of the casing, an internal circuit of the electronic bolt seal is automatically disrupted so that the tampering of the electronic bolt seal can be detected.

Description:
TECHNICAL FIELD OF THE INVENTION 
       [0001]    The present invention is generally related to electronic bolt seals, and more particular to a tamper-proof electronic bolt seal. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]      FIG. 1  depicts a conventional electronic bolt seal 90 which contains a bolt 91 and a seal body 92. A radio-frequency identification (RFD) chip is configured in the bolt 91 whereas an antenna is configured in the seal body 92. By pushing the bolt 91 through a door latch 93 into the seal body 92, a container 94 is secured. As the bolt 91 contacts the antenna inside the seal body 92, the bolt 91 becomes an external antenna. A reader is used to send an electromagnetic wave which is received by the external antenna of the electronic bolt seal 90. The RFID chip then turns the power of the electromagnetic wave into an electric voltage and uses the electronic voltage to modulate and radiate an identification code of the RFID chip into an electromagnetic wave through the external antenna. The reader receives and demodulates the electromagnetic wave, and obtains the identification code. Through the identification code, customs can learn the identification of the container so as to achieve automatic identification and management. In addition, if a burglar tries to steal the cargo inside the container and cuts the bolt 91, customs can be altered through the identification electromagnetic wave. 
         [0003]    However, as shown in  FIG. 2 , a burglar can use a grinding wheel 95 to grind the bolt head 911 of the bolt 91 so that its diameter is smaller than that of the latch hole 931 of the door latch 93. Then the electronic bolt seal 91 can be removed from the door latch 93 without being damaged. After stealing the container 94&#39;s cargo, the burglar simply plugs the electronic bolt seal 90 upside down back into the latch hole 931 and the customs is not alerted. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention provides a tamper-proof electronic bolt seal. The gist of the present invention lies in the bolt assembly which contains a casing, and a circuit board installed inside the casing. When a burglar grinds a bolt head of the casing, an internal circuit of the electronic bolt seal is automatically disrupted so that the tampering of the electronic bolt seal can be detected. 
         [0005]    The foregoing objectives and summary provide only a brief introduction to the present invention. To fully appreciate these and other objects of the present invention as well as the invention itself, all of which will become apparent to those skilled in the art, the following detailed description of the invention and the claims should be read in conjunction with the accompanying drawings. Throughout the specification and drawings identical reference numerals refer to identical or similar parts. 
         [0006]    Many other advantages and features of the present invention will become apparent to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a schematic diagram showing a conventional electronic bolt seal securing a container. 
           [0008]      FIG. 2  is a schematic diagram showing the scenario of tampering a conventional electronic bolt seal. 
           [0009]      FIG. 3  is a perspective break-down diagram showing the various components of an electronic bolt seal according to an embodiment of the present invention. 
           [0010]      FIG. 4  is a perspective diagram showing the attachment of a circuit board to an insulating piece of the electronic bolt seal of  FIG. 3 . 
           [0011]      FIG. 5  is a perspective diagram showing a bolt assembly and a seal body of the electronic bolt seal of  FIG. 3  before the bolt assembly is plugged into the seal body through a latch. 
           [0012]      FIG. 6  is a sectional diagram showing the bolt assembly and the seal body of  FIG. 5 . 
           [0013]      FIG. 7  is a sectional diagram showing the bolt assembly and the seal body of  FIG. 5  after the bolt assembly is plugged into the seal body through the latch. 
           [0014]      FIG. 8  is a sectional diagram showing the bolt assembly and the seal body of  FIGS. 5  after the bolt assembly is tampered. 
           [0015]      FIG. 8 a    is a sectional enlarged diagram showing a portion of  FIG. 8 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    The following descriptions are exemplary embodiments only, and are not intended to limit the scope, applicability or configuration of the invention in any way. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Various changes to the described embodiments may be made in the function and arrangement of the elements described without departing from the scope of the invention as set forth in the appended claims. 
         [0017]    As shown in  FIGS. 3 to 8   a , an electronic bolt seal according to an embodiment of the present invention contains a bolt assembly A and a seal body B. The bolt assembly A is plugged axially downward into the seal body B when locking a door latch C. The seal body B and the door latch C are based on existing art and their details are omitted. The gist of the present invention lies in the bolt assembly A which contains the following components. 
         [0018]    The bolt assembly A has an electrically conductive casing  10  which contains a bolt body  11 , a bolt head  12  at a top end of the bolt body  11 , a channel  13  running axially downward through the bolt head and the bolt body  11 , and a ring  14  threaded through by the bolt body  11  and rested against the bolt head  12 . The bolt body  10  has a smaller diameter than that of a latch hole C 1  of the door latch C, which in turn is smaller than the bolt head  12 &#39;s diameter so that the bolt body  11  can threads through the latch hole C 1  until the bolt head  12  is blocked by the latch hole C 1 . The channel  13  contains a ring section  13 B and a chamber section  13 A, sequentially arranged along a top segment of the channel  13 . The ring section  13 B has a larger diameter than that of the chamber section  13 A, which in turn is not less than that of the latch hole C 1 . The chamber section  13 A thereby forms a first blocking element of the casing  10 . The ring section  13 B is to receive a top cover  15  for sealing a top end of the channel  13 . A first fastening element  16  is configured around a circumference of a bottom portion of the bolt body  11 . A top portion of the casing  10 , the ring  14 , and the top cover  15  are all wrapped inside a plastic waterproof cover  17 . The bolt body  11  and the ring  14  jointly allow the casing  10  to rest reliably in the latch hole C 1  so that, during the transportation of a container, the seal body B does not dangle and collide against the container door, thereby enhancing the life and performance of the electronic bolt seal. A bottom edge of the cover  17  has a downward extended wedge  171 . 
         [0019]    The bolt assembly A further contains an elongated circuit board  20  housed in the channel  13 . The circuit board  20  has a number of through holes  21 , a converging bottom end  22 , and a control circuit  23  on a front surface. The control circuit  23  contains a wire layout  231 , a bottom contact  232  connected to the wire layout  231 , a top contact  233  connected to the wire layout  231 , an RFID chip  234  on the wire layout  231 , a battery  235  powering the RFID chip  234 . The bottom contact  232  is at a tip of the converging bottom end  22 , whereas the top contact  233  is at a top end of the circuit board  20 . The bolt assembly A further contains an insulating piece  30  which has a number of pins  31  extended from a front surface and threading through the through holes  21  of the circuit board  20 . The circuit board  20  is as such attached to the insulating piece  30  and the two are jointly housed inside the channel  13 . A second blocking element  32  and a third blocking element  33  are configured on a top end and a bottom end of the insulating piece  30 , respectively. The second blocking element  32  contains two lower elastic pieces  321  forked downward and a bended upper elastic piece  322 . The lower elastic pieces  321  elastically contact a bottom side of the chamber section  13 A and the upper elastic piece  322  elastically contacts a bottom side of the top cover  15 . Through the upper and lower elastic pieces  322  and  321 , the insulating piece  30  and the circuit board  20  are elastically suspended and limited in the channel  13 , and do not fall off through the channel  13 . In the meantime, the top contact  233  is below the upper elastic piece  322  and does not electrically contact the top cover  15 . The casing  10  therefore cannot function as an external antenna electrically connecting the RFID chip  234 . The third blocking element  33  is located below the channel  13  and has a greater diameter than that of the channel  13 . The third blocking element  33  has a slot  331  for the converging bottom end  22  to penetrate through so that the bottom contact  232  is slightly exposed from a bottom side the third blocking element  33 . 
         [0020]    As illustrated in  FIGS. 5, 6, and 7 , the bolt assembly A is plugged into the seal body B through the latch hole C 1  of the door latch C. The first fastening element  16  engages a second fastening element B 1  in the seal body B and the bolt assembly A cannot be unplugged, thereby locking the door latch C. In the meantime, the third blocking element  33  presses an internal antenna B 2  inside the seal body B and the bottom contact  232  contacts the internal antenna B 2 . The RFID chip  234  as such is electrically connected with the internal antenna B 2  inside the seal body B. On the other hand, the top contact  233  is moved upward to contact the top cover  15 . The casing  10  therefore is electrically connected with the RFID chip  234  and functions as an external antenna. The electronic bolt seal is then in operation. In addition, the seal body B has a notch B 3  matching the wedge  171  of the plastic cover  17  so that the bolt assembly A after being plugged into the seal body B cannot be turned, thereby securing the bottom contact  232 &#39;s reliable contact with the internal antenna B 2 . 
         [0021]    As shown in  FIGS. 7 and 8 , if a burglar grind the bolt head  12  to a diameter smaller than that of the latch hole C 1 , the chamber section  13 A would be destroyed and the top cover  15  would fall off from the bolt assembly A. The top contact  233 &#39;s electrical connection with the top cover  15  is therefore interrupted and the casing  10  would fail to function as the external antenna for the RFID chip  234 . Moreover, the top cover  15 &#39;s falling off releases a pressure on the bottom contact  232 &#39;s pressing the internal antenna B 2 . Also due to the internal antenna B 2 &#39;s resilience, the third blocking element  33  breaks the electrical connection between the bottom contact  232  and the internal antenna B 2 . As described, both the external antenna and the internal antenna B 2  would fail to receive the electromagnetic wave from a reader, and fail to radiate the identification code from the RFID chip  234 . The reader (e.g., operated by the customs) therefore can be altered. 
         [0022]    Please note that the insulating piece  30  can be simplified if the second and third blocking elements  32  and  33  are riveted or bolted to the top and bottom ends of the circuit board  20 , respectively. 
         [0023]    While certain novel features of this invention have been shown and described and are pointed out in the annexed claim, it is not intended to be limited to the details above, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention.