Electronic security seal

Details Electronic security seal Electronic security seal

1999-04-16

2001-07-24

Hofsass, Jeffery (Department: 2632)

Communications: electrical

Condition responsive indicating system

Specific condition

C340S539230, C340S542000, C070S03800C, C070S03800C

Reexamination Certificate

active

06265973

ABSTRACT:

This invention relates to security seals of the type including a bolt and a locking body for securing a hasp, the seal including electronics for transmitting the locked and tampered states of the seal.
In the cargo industry, containers are widely employed. The containers have doors which are locked shut with hasps and secured with locking seals. Such seals include a steel bolt having a head and shank which is attached to a locking body having a shank locking mechanism. When the shank is inserted into the body, a locking collet or other arrangement permanently locks the shank to the body. For example, reference is made to commonly owned U.S. Pat. Nos. 5,005,883, 5,127,687, 4,802,700, 5,347,689, 5,413,393 and others for the disclosure of various seals of the type described.
Cargo containers are shipped via boat, train and truck. Hundreds of containers may be on a single boat. When the containers are unloaded they may be subject to tampering and vandalism. It is important that such tampering be immediately noted to preclude theft of valuable cargo. To assist in such theft and tampering prevention, prior art seals are assigned serial numbers. These seals are then assigned to a container and lock the assigned container. The serial number, container number, the carrier, and the location are then entered into a local computer manually. The entry then is manually made to show that the container is being shipped out of that location. Should a seal be tampered with, the event may be discovered at a different time and different location.
An electronic tagging device is commercially available that is programmable and which transmits information that is programmed, such as tagging identification serial numbers and other information as desired. This is referred to as radio frequency identification (RFID) which is well known in the art. Generally, an RFID tag will have a radio frequency (RF) transmitter, an RF receiver, an RF modulator, and a memory. The memory retains the digital code manifesting the identification number. The RF modulator extracts the digital code representing the identification number as a modulated signal which is applied to the RF transmitter. The RF receiver receives interrogation and control signals which manifest a request for the identification number.
Such systems provide security tagging for high value merchandise as it is transferred from the manufacturer to the consumer. Other applications include tagging of animals, humans and vehicles such as trucks and their cargo containers. Other applications include automatic toll collection systems.
FIG. 19
illustrates a prior art RFID communication system
214
. The system includes an interrogator
216
and an RFID tag
218
. The interrogator
216
includes a host controller
220
to process received information from the RFID tag
218
via antenna
222
and receiver
224
. To retrieve information from the RFID tag
218
, the host controller
220
generates an interrogation command signal which is transmitted by transmitter
226
and antenna
228
as signal
230
. The tag
218
transmits RFID signal
232
via antenna
234
in response to receipt of the interrogation command signal
230
. The receiver
224
receives the signal
232
via antenna
222
. The signal
232
manifests the identification number of the tag
218
.
The RFID tag
218
has an antenna
236
and a receiver
238
to receive the interrogation command signal
230
from the interrogator
216
. The receiver
238
transfers the received command signal to a controller
240
. The controller
240
interprets the command and extract the corresponding identification number (ID) from memory
242
. The extracted identification number is then transferred by the controller
240
to transmitter
244
which transmits the ID to antenna
234
which broadcasts the signal
232
.
In active RFID tags, power
246
is provided by a battery system. In passive systems, the power is induced from the received signal. The signal
232
transmitted by the RFID tag
218
is modulated back scatter of the original signal transmitted by the interrogator
216
.
The controller
240
may have an interface, not shown, to receive data from external transponders such as temperature sensors, pressure sensors, global positioning sensing and other telemetric measurement data.
When multiple RFID tags
218
are simultaneously in close proximity to the interrogator
216
and the interrogator is broadcasting interrogation and control signals, the RFID tags may simultaneously respond. The responses may collide and the identification codes may be garbled and lost. Generally, the interrogator will rebroadcast commands to establish an order of broadcast of the RFID tags. This ordering of the broadcast is possible only from active RFID tags.
U.S. Pat. No. 5,479,160 to Koelle, incorporated by reference herein, provides an inexpensive circuit that consumes low power, can detect low level RF signal and RF signals of varying strength, and can reject intermittent low level RF interference. Logic circuitry is provided to insure that the read/write circuitry of the tag will not be activated unless the polarity of the reactivation signal is detected for a specified time.
U.S. Pat. No. 5,541,604 to Meier, incorporated by reference herein, allows the use of a single set of circuitry in each of the interrogator and the transponder for transmission and reception of both powering and communication signals ;without the need for synchronization between interrogators. PWM (pulse width modulation), PPM (pulse position modulation and FSK (frequency shift keying) transmission systems are disclosed.
U.S. Pat. No. 5,485,154 to Brooks et al, incorporated by reference herein, encompasses systems and methods of communicating with or identifying more than one remote device employing random sequence selection of a carrier signal frequency from a defined set of carrier frequencies. The remote device selects a carrier signal frequency and transmits data such as an identification code using that frequency and then reselects the same or a new carrier signal frequency for the next transmission event.
The aforementioned copending application provides a communication system that allows multiple transmitters of telemetric data to communicate with an interrogating receiving system and is incorporated in the present invention circuit.
However, there are no mechanical seals of the type described in the aforementioned seal patents or copending application for use with such electronic tagging devices presently available. The present inventors recognize a need for such electronic tagging circuits for use with bolt seals to resolve a long felt problem in the cargo shipping field.
An electronic seal according to the present invention comprises a housing having a cavity that receives a bolt that has an elongated shank and a head. Signal generating means are in the cavity. Bolt locking means receive and lock the shank to the housing. Circuit means in the cavity are responsive to the received locked shank for causing the signal generating means to generate a first signal manifesting a first code and a locked seal and a second signal manifesting a second code and a tampered condition when the shank is severed.
In one aspect, an electrical conductor completes a circuit with the circuit means and extends along a length of the shank.
In a further aspect, an electrically insulated tube extends from and is locked to the cavity for receiving the shank therein, the tube including the conductor therein.
The conductor preferably extends adjacent to the head from the cavity, the tube for moisture sealing its interface with the bolt.
In a further aspect, the bolt is electrically conductive, the conductor including the bolt, an electrical insulator about the shank and an electrically conductive layer over the insulator, and contact means for electrically connecting the layer to the circuit means.
The housing preferably includes an opening for receiving means for programming the circuit means with seal identifying data, the housing including a door for selectivel

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