Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-08-29
2001-10-30
Mullen, Thomas (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C324S207210, C340S539230, C340S545100
Reexamination Certificate
active
06310549
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electronic security systems and in particular to wireless security systems.
BACKGROUND OF THE INVENTION
In the U.S., a burglary currently occurs every 13 seconds. Accordingly, security systems have gained popularity for home owners and businesses alike. For businesses that lease spaces, a security system is a necessity to compete in the marketplace. Whether it be the lease of apartments, office space, industrial space or self-storage facilities, the ability to attract new customers is greatly dependent upon a reliable security system to protect the tenants' valuable assets.
For self-storage facilities a reliable security system is important, not only to attract new tenants, but also to retain existing tenants. The term self storage facility describes a plurality of freestanding buildings with a plurality of separate, individual storage units that are typically rented on a monthly basis. In many of these facilities, tenants are responsible for the security of their units. Accordingly, the tenant will put a pad lock on the door to the unit to prevent theft. Unfortunately, the padlock can be easily defeated by simply using a bolt cutter to remove the padlock and gain access to the contents of the unit.
Electronic door alarms are also used in some self-storage facilities. Typically, these individual door alarms are hardwired devices that use a magnetic switch mounted to the floor or wall next to the door and a magnet mounted on the moving portion of the door. When the door is opened the magnet moves away from the switch, causing the switch to open the circuit, thereby signaling the opening of the unit door.
There is a trend toward offering these door alarms in new self-storage facilities. Self-storage facilities that have individual unit door alarms can normally attract a higher number of tenants and charge a higher rent per square foot than those facilities without the alarms. As a result, there is pressure on the owners of existing units to update security in order to retain existing tenants and attract new tenants.
Retrofitting an existing self storage unit with individual door alarms, however, is a difficult task. A hardwired security system is not a viable option, due to logistical problems and overwhelming expense. Typically, magnetic contacts are mounted inside the unit to protect from being defeated by a thief. If the magnetic contacts are mounted inside the unit, however, there is the need to access a tenant's space to install the system. Since the tenant typically puts a padlock on the unit, it is impossible for the owner of the facility to access the individual units without getting permission and cooperation from each tenant. As a result, this type of system is difficult to implement.
If the magnetic contacts were placed on the outside of each unit, in order to avoid accessing all the individual units, there are obvious security concerns. Placing the magnet contacts outside the unit gives a thief access to both the magnet and magnetic switch. Since standard magnets and biased magnets can be easily defeated, the owner of the facility would be forced to use a high-security magnet. Unfortunately, the cost of these high-security magnets dramatically increases the total cost of the system. The cost of using a high-security magnet, along with the costs of wiring, conduit and installation, prevents hardwired systems from being a cost-effective option for retrofitting existing self-storage facilities with security systems.
In order to lower the costs of wiring an existing unit, wireless security systems have been proposed. The wireless security systems work in a similar manner to that of magnetic contact systems. If the magnet moves away from the switch the system will transmit an RF alarm signal to a remote station.
Unfortunately, wireless systems do not work within either new or existing self-storage units, due to the typical metal construction of the units. As a result of the metal construction, the wireless detectors cannot transmit outside the unit to a remote station in a reliable manner. Moreover, the installation of the magnetic contacts, as with the hardwired systems, requires access to all the individual units.
Therefore, there is a need for a reliable security system that can be easily installed in either new or existing self-storage facilities in a cost-effective manner.
SUMMARY OF THE INVENTION
According to its major aspects and briefly described, the present invention is a wireless security system. Although the system will be described with respect to its application in self-storage facilities, it is clear that the system could be used anywhere a security system is used. Each unit in the facility is preferably equipped with an alarm sensor that is mounted outside the unit on the door or window that allows access to the unit. The alarm sensor continuously detects the position of the door or window with which it is associated. If the door's or window's position is changed, the alarm sensor transmits an alarm signal to the network controller. If an intruder attempts to disable or override an alarm sensor, the alarm sensor will transmit a tamper signal to the network controller.
Each alarm sensor contains three magnetoresistive sensors that are capable of detecting the three-dimensional vector (magnitude and phase) of a magnetic field. Preferably, the magnetoresistive sensors detect the orientation of the door or window based upon the earth's magnetic pole. As a result, a separate magnet is not required and the alarm sensor can detect movement of a door, regardless of whether the door opens about the vertical or horizontal plane. The three-dimensional vector output of the magnetoresistive sensors is received by a microprocessor on-board the alarm sensor. The microprocessor continuously compares the magnetoresistive sensors output with the maximum allowable position of the door or window. If the magnetoresistive sensors' output exceeds the maximum allowable position, the microprocessor will signal an alarm, which is transmitted to the network controller via a transmitter on-board the alarm sensor.
A major advantage of the present invention is that the landlord need not gain access to a tenant's space in order to install the security system. A major feature of the present invention, installation of the sensors on the outside of the door or window, is the key to eliminating the need to access the tenant's space. In self-storage facilities, for example, where the tenant can prevent landlord access, the logistics of obtaining access to each unit for installation is virtually impossible. Accordingly, this feature eliminates the logistical problems with retrofitting an existing unit.
The position of an alarm sensor outside the door or window is a major feature of the present invention. With the alarm sensor outside the unit there is no signal attenuation so a wireless system can be used. As a result of using a wireless system, installation costs are substantially reduced, thereby allowing security systems to be installed cost effectively in existing units.
Another advantage of the present invention is the elimination of the need for a separate magnet and magnetic switch. In the present invention, the alarm sensor uses magnetoresistive sensors to prevent the need for an external magnet. Since the magnetoresistive sensors detect the position of the door or window based upon the earth's magnetic pole, the use of an external magnet, which could be easily defeated, is not necessary.
These and other features and their advantages will be apparent to those skilled in the art from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings.
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patent: 4359646 (198
Crane Jerry
Crane Richard
Loftin Jon
Digitech International
Mann Michael A
Mullen Thomas
Nexsen Pruet Jacobs & Pollard LLC
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