Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-03-02
2004-08-10
Tong, Nina (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S568100, C340S637000, C340S572100, C324S110000
Reexamination Certificate
active
06774807
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to detection of tampering with meters, communication devices and similar devices.
BACKGROUND OF THE INVENTION
As the cost of human intervention in reporting has increased, automation of many of the reporting functions has become more attractive in the commercial world. For example, the present meter values of many electrical, gas, water, vehicle parking and similar meters can now be electronically read and transmitted to a remote reporting station. As another example, many burglar alarms, intrusion alarms, fire alarms, environmental alarms and the like transmit alarm signals and all-clear signals to a remote monitoring station.
A communication device, meter device and the like is referred to collectively herein as a communications/meter device or “CMD”. A particular CMD may be inspected by a company representative once or a few times per year, or more often or less often. In some instances, it is to the advantage of the user of a CMD, or to one who would tamper with a CMD, to interfere with normal operation of the CMD by arranging for the CMD to report spurious values or conditions that do not accurately represent the present use or environment of the CMD. In some instances, a user of metered electricity, gas and/or water may attempt to tamper with the associated meter for substantial time intervals by (1) turning the meter off, by pulling all or a portion of the meter away from its normal attachment site, or (2) reversing the meter direction so that a meter value is caused to decrease, rather than increase, with continuing consumption of the metered quantity. In other instances, an intruder, such as a burglar, may attempt to tamper with an intrusion alarm to conceal the fact that this person is present without authorization on some part of protected premises.
What is needed is a system and associated method for detecting and promptly reporting any of certain types of attempted tampering with a CMD by sensing any of certain classes of movement of a CMD The system should operate automatically and should be capable of trouble-free operation, with little maintenance required, over long time intervals. The system should be capable of detecting attempted tampering with the CMD itself and with the tamper detection system. Preferably, the system should allow retrofitting or inclusion with the original CMD equipment so that the system's presence and operation are not obvious to a CMD user. The system should be flexible enough to respond to different types of tampering attempts, and the cost of installing the system should be a small fraction of the cost of the CMD. The system should allow tamper reporting at the CMD and/or of transmission of a tamper reporting signal to a remote reporting station.
SUMMARY OF THE INVENTION
These needs are met by the invention, which uses magnetic, electrical and/or mechanical responses by a tamper detection mechanism to monitor and report on attempts to rotate, translate or remove whatever attachment device (bolt, screw, etc.) are used to attach the meter to a CMD attachment site. In one embodiment, the invention uses one or more reed switches, oriented in a first preferred direction, and an adjacent permanent magnet, oriented in a second preferred direction and attached to an attachment device, to detect attempted tampering with the CMD. An electrical current source is connected to a first end of the reed switch.
In one version of this embodiment, the reed switch is normally positioned in a closed state, allowing a small electrical current (or a voltage) be sensed at a current-sensing (or voltage-sensing) device connected to a second end of the reed switch. If an attempt is made to rotate or translate the attachment device, the projection of the permanent magnet field at the reed switch changes sufficiently to cause the reed switch to open, thereby interfering with the current (or voltage) that would otherwise be sensed and triggering a tamper alarm signal. In a second version of this embodiment, the reed switch is normally positioned in an open state, and a tamper alarm signal is triggered when the reed switch changes to a closed state.
In a second embodiment of the invention, a micro-switch and attached plunger are located adjacent to a CMD attachment device that has a small detent, or other surface irregularity against which the plunger is urged by a spring-like mechanism. Any attempt to rotate or translate the CMD attachment device causes the plunger to move longitudinally (in or out) from its normal location. Longitudinal movement of the plunger by more than a threshold amount causes the micro switch to generate a tamper alarm signal.
In a third embodiment of the invention, a first sector of a CMD attachment device is electrically conducting and a second (remaining) sector of the attachment device is non-conducting. Two terminals of a circuit, which includes a current or voltage source and includes a current sensor or a voltage sensor, are movably connected to the attachment device at spaced apart locations. When the attachment device is rotated, or alternatively translated, beyond a threshold amount, the portion of the attachment device between the two terminals transitions from conducting to non-conducting, or from non-conducting to conducting, and a tamper alarm signal is generated.
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Glorioso Charles
Lehfeldt Carl Robert
Waters Christopher J.
Blakely , Sokoloff, Taylor & Zafman LLP
Cadence Design Systems Inc.
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