Electronic security seal

• US 7,239,238 B2
• Filed: 03/16/2005
• Issued: 07/03/2007
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: E J Brooks Company
• Original Assignee: E J Brooks Company
• Inventors: Debrody, Robert F., Ruth, Donald A., Tester, Theodore R.
• Primary Examiner(s): Hofsass; Jeffery
• Assistant Examiner(s): Labbees; Edny
• Application Number:
  US11/081,930
• Publication Number:
  US 20050231365A1
• Time in Patent Office: 839 Days
• Field of Search: 340/568.1, 340/568.2, 340/572.1, 340/539.31, 292/307.R
• US Class Current: 340/539.31
• CPC Class Codes: G06K 19/07798 part of the antenna or the integrated circuit being adapted for rupturing or breaking, e.g. record carriers functioning as sealing devices for detecting not-authenticated opening of containers electronic seals G09F3/03
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2448 Tag with at least dual detection means, e.g. combined inductive and ferromagnetic tags, dual frequencies within a single technology, tampering detection or signalling means on the tag
• CPC Class Codes: G09F 3/0335 using RFID tags
• CPC Class Codes: G09F 3/0347 having padlock-type sealing means padlocks in general E05B67/00
• CPC Class Codes: G09F 3/0352 using cable lock
• CPC Class Codes: Y10T 292/48 Seals

Abstract

A battery operated cable security seal for cargo containers and the like includes a housing with a transparent cover for visual inspection of illuminated internal green or red LEDs, the red LED representing a tampered state of a stranded metal locking cable, which has a length sufficient to secure the keeper bars and hasp of a cargo container door. The cable has an internal conductor whose conductivity, e.g., resistance, manifests a tampered condition when severed and also if reattached, e.g., by a solder or spliced joint and so on. The electrical continuity of the conductor is monitored by a circuit in one embodiment for a severed state, i.e., tampering, and whose resistance is monitored in a second embodiment correlated optionally to either or both ambient temperature and a battery output voltage. The seal housing has two compartments one being hermetically sealed and contains the circuitry and the other containing a cable locking device for receiving and locking the cable to the seal. The circuit includes an RFID tag which may be part of a mesh network configuration with other tags.

Claims

1. An electronic security seal comprising:

a housing having a cavity;

a cable locking device in the cavity;

a cable having a hollow core and a first sealed free end and a second end, the second end being secured fixedly secured in the cavity, the first free end for selective insertion into engagement with the received locking device to lock the free end in the cavity;

an electrical conductor in the cable hollow core, the conductor having a given resistance R, the conductor forming a loop within the cable and extending adjacent to the cable sealed first end, the loop terminating in a second free end with the conductor forming a pair of conductors extending beyond the cable at the cable second end and electrically connected to a first circuit;

the first circuit located in the housing cavity including a signal generating circuit for generating a first signal manifesting a first cable locked state indicating that the cable free end is locked, the first circuit being responsive to a sensed tamper condition of the conductor for generating a second signal manifesting the sensed tampered condition of the locked cable; and

a resistance measuring circuit for periodically measuring the resistance value of said electrical conductor loop, the first circuit being responsive to the measuring circuit for generating the second signal when the resistance value of the conductor loop differs from a predetermined reference value to provide a detected tamper condition;

the first circuit including a power source having an output voltaae that decreases in value during a time period, the first circuit being arranged to correlate the predetermined reference resistance value of the conductor to at least one of a measured ambient temperature value and a measured decreasing power source output voltage value.

2. The electronic security seal of claim 1 wherein the first circuit is arranged to correlate the predetermined reference resistance value of the conductor to both the measured ambient temperature value and to the measured decreasing power source output voltage value.

3. The electronic security seal of claim 1 wherein the power source is at least one of a battery or solar cell.

4. The electronic security seal of claim 1 wherein the first circuit includes a stored table of reference power source output voltage values each corresponding to the predetermined a reference resistance value, the circuit for measuring the power source output voltage value and for comparing the measured output voltage value with the stored reference voltage values to obtain a reference resistance value corresponding to the measured output voltage and for comparing the measured resistance value of the conductor to the obtained reference resistance value.

5. The electronic security seal of claim 1 wherein the first circuit includes an ambient temperature sensor and a stored table of reference temperature values each corresponding to a reference resistance value, the circuit for periodically determining the ambient temperature and for comparing the determined ambient temperature value with the stored reference temperature values to obtain the predetermined reference resistance value and for comparing the measured resistance value of the conductor to the obtained reference resistance value.

6. The electronic security seal of claim 1 wherein the first circuit includes a table of reference resistance values each correlated to a given power source output voltage and ambient temperature, the first circuit for measuring the power source output voltage, the ambient temperature and the conductor resistance and for comparing the measured voltage and ambient temperature to the table voltage and temperature values to obtain the predetermined reference resistance value, the first circuit for comparing the measured resistance value to the predetermined reference resistance value.

7. The electronic security seal of claim 1 wherein the first circuit is responsive to a command signal, the first circuit including a memory for storage of time/date data and being arranged for periodically transmitting an electronic signal containing the time/date and tampered status of the cable during that period upon receipt of the command signal.

8. The electronic security seal of claim 1 wherein the first circuit includes an alarm circuit for generating and transmitting an alarm signal including a data signal manifesting the time/date stamp of the alarm signal upon detection of a tamper condition of the cable manifested by the measured resistance value of the conductor.

9. The electronic security seal of claim 1 including an electrical contact arranged to engage the received locked cable free end for arming the first circuit to commence periodically polling and recording the locked status of the cable and associated time/date of the recording.

10. The electronic security seal of claim 1 including an arming arrangement responsive to a received arm command signal for arming the first circuit and commencing monitoring the locked cable tamper free status.

11. The electronic security seal of claim 10 including a shut down arrangement for shutting down the first circuit at the end of a predetermined period after the arming of the first circuit.

12. The electronic security seal of claim 1 wherein the housing includes a first compartment for receiving the cable and a second compartment containing the first circuit, the first and second compartments being hermetically sealed from each other in the cavity, the second compartment being hermetically sealed from the ambient atmosphere.

13. The electronic security seal of claim 12 wherein the first and second compartments have a common wall, the conductor exiting the cable in the first compartment and passing into the second compartment through the common wall and sealed to the common wall with a hermetic seal.

14. The electronic security seal of claim 1 wherein the locking device includes an extension, the extension for receiving the cable second end, and a cable securing arrangement for fixedly securing the cable second end to the extension.

15. The electronic security seal of claim 14 wherein the arrangement for securing the cable second end to the extension comprises a staked portion in the extension.

16. The electronic security seal of claim 15 wherein the cable with the conductor is aligned with the staked portion.

17. The electronic security seal of claim 14 wherein the cable second end enters the extension in a first cable region, the conductor exiting the cable in a second cable region between the first region and the housing in the cavity.

18. The electronic security seal of claim 13 wherein the common wall forms a lid for enclosing the second compartment.

19. The electronic security seal of claim 1 wherein the seal is for securing the door of a cargo container, the door having keeper bars and a hasp, the cable having a length sufficient to secure the keeper bars and hasp.

20. An electronic securing seal for securing a cargo container door comprising:

a housing having a cavity;

a cable locking device in the cavity;

a cable having a hollow core and a first sealed free end and a second end, the second end being secured fixedly secured in the cavity, the first free end for selective insertion into engagement with the received locking device to lock the free end in the cavity,; and

an electrical conductor in the cable hollow core, the conductor having a given resistance R and electrically connected to a first circuit;

the first circuit located in the housing cavity including a signal generating circuit for generating a first signal manifesting a first cable locked state indicating that the cable free end is locked, the first circuit being responsive to a sensed tamper condition of the conductor for generating a second signal manifesting the sensed tampered condition of the locked cable;

wherein the first circuit includes a cower source having an output voltage that decreases in value during a time period, the first circuit being arranged to correlate the given reference resistance value R of the conductor to at least one of a measured ambient temperature value and a measured decreasing power source output voltage value.

21. The electronic security seal of claim 20 wherein the housing includes a first compartment for receiving the cable and a second compartment containing the first circuit, the first and second compartments being hermetically sealed from each other, the second compartment being hermetically sealed from the ambient atmosphere.

22. The electronic security seal of claim 20 wherein the first circuit is arranged to correlate the given reference resistance value R of the conductor to both the measured ambient temperature value and to the measured power source output voltage value.

23. The electronic security seal of claim 21 including a lid for covering the first compartment for sealing the first compartment from the second compartment.

24. The electronic security seal of claim 23 wherein the cable has a hollow core and a conductor in the core, the circuit for determining the conductivity of the conductor and for issuing a tamper alarm when the conductivity manifests a tampered cable, the conductor for passing through the lid into electrical engagement with the circuit including a sealant for sealing the conductor to the lid.

25. The electronic security seal of claim 20 wherein the electrical conductor forms a loop in the cable core and manifests a given electrical conductivity and having at least one end exiting the cable at the cable second end in the first compartment.

26. The electronic security seal of claim 25 wherein the cable second end is staked to the locking device with the staked region aligned with the conductor.

27. The electronic security seal of claim 20 further including an RFID tag associated with the first circuit, the tag for initializing the first circuit to an armed condition in response to a received arm command signal.

28. The electronic security seal of claim 27 wherein the tag includes a relay circuit for relaying commands and data to and from adjacent seal tags forming a mesh network configuration.

29. The electronic security seal of claim 21 wherein the electrical conductor is electrically connected to the first circuit and sealed to the lid;

the first circuit being arranged to compare the measured resistance of the conductor to the correlated given reference resistance value R and for generating a locked good cable signal when the measured resistance matches the given reference value R and for generating a tamper alarm signal when the measured resistance value is different than the reference value R beyond a predetermined range of resistance values.

30. The electronic security seal of claim 29 wherein the first circuit is responsive to the voltage from the power source and is arranged to compare the measured resistance of the conductor to the given reference resistance value R at both a given temperature and a given power source voltage value.

31. The electronic security seal of claim 29 wherein the given reference resistance value R is a function of the conductor open or closed state.

32. The electronic security seal of claim 20 wherein the circuit includes lights manifesting a respective tampered and normal condition of the cable.

33. The electronic security seal of claim 20 wherein the conductor includes a joint when tampered with, the first circuit for determining the presence of the joint and for issuing a tampered condition signal when the joint is present.

34. The electronic security seal of claim 20 wherein the resistance of the conductor varies with ambient temperature and voltage output level of a power source, the first circuit for determining the tampered state of the conductor based on the measured resistance of the conductor as correlated to the values of both the measured ambient temperature and measured power source output voltage.

35. An electronic security seal comprising:

a housing having a cavity;

a cable locking device in the cavity;

a cable having a hollow core and a first sealed free end and a second end, the second end being secured fixedly secured in the cavity, the first free end for selective insertion into engagement with the received locking device to lock the free end in the cavity;

an electrical conductor in the cable hollow core, the conductor having a given resistance R, the conductor forming a loop within the cable and extending adjacent to the cable sealed first end, the loop terminating in a second free end with the conductor forming a pair of conductors extending beyond the cable at the cable second end and electrically connected to a first circuit;

the first circuit located in the housing cavity including a signal generating circuit for generating a first signal manifesting a first cable locked state indicating that the cable free end is locked, the first circuit being responsive to a sensed tamper condition of the conductor for generating a second signal manifesting the sensed tampered condition of the locked cable;

a resistance measuring circuit for periodically measuring the resistance value of said electrical conductor loop, the first circuit being responsive to the measuring circuit for generating the second signal when the resistance value of the conductor loop differs from a predetermined reference value to provide a detected tamper condition; and

the first circuit including a power source having an output voltage that decreases in value dunng a time period, the first circuit being arranged to correlate the predetermined reference resistance value of the conductor to a measured decreasing power source output voltage value.

36. An electronic security seal comprising:

a housing having a cavity;

a cable locking device in the cavity;

a cable having a hollow core and a first sealed free end and a second end, the second end being secured fixedly secured in the cavity, the first free end for selective insertion into engagement with the received locking device to lock the free end in the cavity;

an electrical conductor in the cable hollow core, the conductor having a given resistance R, the conductor forming a loop within the cable and extending adjacent to the cable sealed first end, the loop terminating in a second free end with the conductor forming a pair of conductors extending beyond the cable at the cable second end and electrically connected to a first circuit;

the first circuit located in the housing cavity including a signal generating circuit for generating a first signal manifesting a first cable locked state indicating that the cable free end is locked, the first circuit being responsive to a sensed tamper condition of the conductor for generating a second signal manifesting the sensed tampered condition of the locked cable;

a resistance measuring circuit for periodically measunng the resistance value of said electrical conductor loop, the first circuit being responsive to the measuring circuit for generating the second signal when the resistance value of the conductor loop differs from a predetermined reference value to provide a detected tamper condition;

the first circuit being arranged to correlate the predetermined reference resistance value of the conductor to a measured ambient temperature value.

37. An electronic securing seal for securing a cargo container door comprising:

a housing having a cavity;

a cable locking device in the cavity;

a cable having a hollow core and a first sealed free end and a second end, the second end being secured fixedly secured in the cavity, the first free end for selective insertion into engagement with the received locking device to lock the free end in the cavity; and

an electrical conductor in the cable hollow core, the conductor having a given resistance R and electrically connected to a first circuit;

the first circuit located in the housing cavity including a signal generating circuit for generating a first signal manifesting a first cable locked state indicating that the cable free end is locked, the first circuit being responsive to a sensed tamper condition of the conductor manifested by a shift in the reference resistance value R from a predetermined amount for generating a second signal manifesting the sensed tampered condition of the locked cable;

the first circuit including a power source having an output voltage that decreases in value during a time period, the first circuit being arranged to correlate the given resistance R value to a measured decreasing power source output voltage value.

38. An electronic securing seal for securing a cargo container door comprising:

a housing having a cavity;

a cable locking device in the cavity;

a cable having a hollow core and a first sealed free end and a second end, the second end being secured fixedly secured in the cavity, the first free end for selective insertion into engagement with the received locking device to lock the free end in the cavity, the cable having a length sufficient to secure the keeper bars and hasp of the cargo container door; and

an electrical conductor in the cable hollow core, the conductor having a given resistance R and electrically connected to a first circuit;

the first circuit located in the housing cavity including a signal generating circuit for generating a first signal manifesting a first cable locked state indicating that the cable free end is locked, the first circuit being responsive to a sensed tamper condition of the conductor for generating a second signal manifesting the sensed tampered condition of the locked cable manifested by a shift in the reference resistance value R from a predetermined amount;

the first circuit being arranged to correlate the reference resistance value R of the conductor to a measured ambient temperature value.