Patent Publication Number: US-2007120698-A1

Title: System for monitoring the proximity of personal articles

Description:
FIELD OF THE INVENTION  
      The present invention relates to wireless systems for protecting personal articles against loss and theft.  
     BACKGROUND OF THE INVENTION  
      People regularly carry personal articles, such as car keys, wallets, cell phones, personal music players and other portable hand-held electronic devices. Many of these articles are small and can easily be left behind or forgotten and become lost. A number of these articles are also common targets of theft, as they may have significant value, contain important information or documents, or have other value to a person. The high value of these articles generally means such that the loss of such articles is a serious concern for the person, and it is desirable to prevent these articles from being forgotten, misplaced and stolen.  
      Some systems exist for locating articles that have already been lost or misplaced. For example, Crabtree et al. (U.S. Pat. No. 6,788,199) discloses a system for locating objects using transceivers attached to objects to be tracked and a handheld portable locating unit, which is carried by a user. The locator communicates wirelessly with the transceivers, and the time taken for a signal to travel round trip from the locator to the transceivers is used to determine an approximate distance between the transceivers and the locating unit. Crabtree also discloses a system utilizing a first locator unit and a second locator unit, in which the first locator unit can locate a transceiver that is outside of its range, but that is within range of the second locator unit. The purpose of the Crabtree system is to allow a user to locate objects and to determine the distance and the bearing to objects that the user now wishes to locate.  
      Kreiner et al. (U.S. Pat. No. 6,900,731) describes a system for locating objects that are lost or misplaced. Monitors that are inductively coupled to passive tags attached to objects or articles to be tracked. The monitors and the tags pass identification signals back and forth. The monitors are in communication with at least one network, and preferably a number of networks. Kreiner discloses the use of multiple monitors wherein the monitors are connected via a network such as a cellular telephone network.  
      Koslar (U.S. Pat. No. 6,404,338) discloses a fixed measuring and security system for protecting an object using fixed transmission systems positioned at control points, wherein the transmission systems communicate with each other, and are adapted to trigger an alarm when a particular object moves outside of predetermined activity areas. This system is not readily adaptable to be used to protect against loss or theft of personal articles.  
      McCall et al. (U.S. Pat. No. 6,738,628) discloses a system for tracking objects within a building for inventory purposes by using an array of fixed transmitting beacons and a radio device associated with an object, such as a personal computer or server computer. Each beacon transmits identification data to the radio device, and may be associated with an existing wireless communication mechanism, such as a Bluetooth network.  
      Bero et al. (U.S. Pat. No. 6,563,427) describes a system of proximity monitoring using a wireless communication system operating on two wireless local area networks, such as cell phone networks. A wireless device, such as a cell phone, communicates with a tracking device attached to an object being tracked, and an alarm is triggered when the monitor is no longer within a predetermined range.  
      None of the aforesaid prior art systems provides a person with an optimized system and apparatus for protecting against the loss or theft of articles carried by the person. There is accordingly a need in the art for a solution that provides a user with a flexible and portable system to protect against the loss and theft of personal articles without requiring a high degree of user involvement.  
     SUMMARY OF THE INVENTION  
      The present invention is directed to a system for monitoring the proximity of personal articles. The system comprises at least one wireless tracking device affixable to at least one portable article to be monitored, a first master wireless communication device for communicating with the at least one tracking device and for determining when the at least one tracking device is outside of a first operating range, and a second portable master wireless communication device for communicating with the at least one tracking device and for determining when the at least one tracking device is outside of a second operating range. The first master communication device and the second master communication device are operable to communicate with each other and to determine whether the first master communication device and the second master communication device are within a predetermined master range. At least one of the first master communication device and the second master communication device is operable to generate an alarm if the second master communications and the second master communication device are not within the predetermined master range. At least one of the first master communication device and the second master communication device is operable to generate an alarm if the least one tracking device is outside of the first operating range and the second operating range.  
      Another aspect of the present invention is a method for preventing the loss of portable personal articles. The method comprises the steps of:  
      (a) providing a user with a first portable master wireless communication device having a first operating range and a second portable master wireless communication device having a second operating range, the first master communication device and second master communication device being in wireless communication with each other;  
      (b) attaching at least one wireless tracking device to a portable personal article, the tracking device being in wireless communication with the first master communication device and the second master communications device;  
      (c) determining whether the first master communication device and the second master communication device are within a predetermined distance from each other and generating an alarm if the first master communication device and the second master communication device are not within the predetermined distance;  
      (d) sending a first locating signal from the first master communication device to the tracking device to determine a first distance between the first master communication device and the tracking device;  
      (e) generating an activation signal activating the second master communication device if the first distance is outside the first operating range;  
      (e) sending a second locating signal from the second master communication device to the tracking device to determine a second distance between the second master communication device and the tracking device; and  
      (f) generating an alarm if the second distance is outside the second operating range. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will now be described, by way of example only, with reference to the following drawings, in which:  
       FIG. 1  is diagram of a system made in accordance with a preferred embodiment of the invention;  
       FIG. 2  is a perspective view of a first master wireless communication device of the system of the present invention, shown inserted into a wallet.  
       FIG. 3  is a perspective view of a second master wireless communication device of the system of the present invention, shown attached to a set of keys.  
       FIG. 4  is a block diagram of a wireless transceiver module and a passive ID tag of the present invention; and  
       FIG. 5  is a flowchart of a method for monitoring the proximity of personal articles, implemented by the system of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      The present invention is directed to a system and method for monitoring the proximity of personal articles, which provides a user with a wearable personal “force-field” that protects against the loss or theft of the personal articles.  
       FIG. 1  shows a system  10  in accordance with a preferred embodiment of the present invention. System  10  comprises a first portable master wireless communication device  12 , a second portable master wireless communication device  14 , and a plurality of wireless tracking devices  22 ,  24 ,  26  and  28  attached to personal articles to be monitored. First master communication device  12  is sized and shaped to be small enough to be conveniently carried by a person, for example by inserting first master communication device  12  into a wallet  13  carried by the user. Second master communication device  14  is also sized and shaped to be carried by the person, and may be attached to a set of car keys  15 , for example.  
      First master communication device  12  has a first operating range  16 , which is of a generally spherical shape and which has a predetermined radius R 1 . Second master communication device  14  has a second operating range  18 , which is also of a generally spherical shape and which as a predetermined radius of R 2 . R 1  and R 2  may be determined in any number of various different ways. For example, R 1  and R 2  may be selected by the user to accord with the user&#39;s personal preferences, or may be hardwired into first master communication device  12  and second master communication device  14 , or may be based on the physical limitations of wireless transceiver technology on first master communication device  12  and second master communication device  14 , or may be determined according to another criteria. In a preferred embodiment, R 1  and R 2  are of generally equal distance, and are preferably about 5-10 feet.  
      First master communication device  12  and second master communication device  14  communicate with each other using first command signals  20  sent from first master communication device  12  to second master communication device  14 , and second command signals  21  sent from second master communication device  14  to first master communication device  12 . First command signals  20  and second command signals  21  may comprise instructions between first and second master communication devices  12 ,  14  and are used to determine the distance between the first and second master communication devices  12 ,  14 . If the distance indicates that the second master communication device  14  is not within a predetermined master range  17  of first master communication device  12 , an alarm is activated on at least one of first and second master communications devices  12 ,  14 . As shown, master range  17  is equal to first operating range  16 .  
      The distance between master communication devices  12 ,  14  may be calculated using different methods. For example, it may be based on the strength of first command signal  20  received by second master communication device  14  or the strength of the second command signal  21  received by first master communication device  14 . The distance may also be calculated by measuring the total round trip time taken for first command signal  20  to be sent from first master communication device  12  to second master communication device  14  and second command signal  21  sent back to first master communication device  12 . Other methods for determining distance may be used as are known in the art.  
      During operation, first master communication device  12  and second master communication device  14  operate together to provide a protective “force-field” which includes the first operating range  16  plus the second operating range  18 .  
      Wireless tracking devices  22 ,  24 ,  26  and  28  receive locating signals  31 ,  33  from first and second master communications devices  12 ,  14 , respectively, and send return signals  35  to first and second master communication devices  12 ,  14 , respectively. The return signal  35  of each wireless tracking device  22 ,  24 ,  26 , and  28  contains a unique identification number, and each tracking device is affixed to a different personal article to be tracked. For example, first wireless tracking device  22  may be affixed to a cell phone  23 , second wireless tracking device  24  may be affixed to a personal music player  25 , third wireless tracking device  26  may be affixed to a watch  27 , and fourth wireless tracking device  28  may be affixed to a laptop  29 .  
      During operation, first master communication device  12  scans for all wireless tracking devices  22 ,  24 ,  26 , and  28  that are associated with first master communication device  12  by sending locating signals  31  to and receiving return signals  35  from wireless tracking devices  22 ,  24 ,  26  and  28 . In this example, first wireless tracking device  22  and third wireless tracking device  26  are both within first operating range  16 , and thus would be quickly detected by first master communication device  12 . However, second wireless tracking device  24  and fourth wireless tracking device  28  are outside of first operating range  16 . First master communication device  12  then sends command signal  20  to second master communication device  14  with instructions to scan for second wireless tracking device  24  and fourth wireless tracking device  28 .  
      Second master communication device  14  receives first command signal  20 , and sends second command signal  21  back to first master communication device  12  acknowledging receipt of instructions. Second master communication device  14  then begins scanning by transmitting locating signals  33  and receiving return signals  35 , and locates second wireless tracking device  24  within second operating range  18 . However, fourth wireless tracking device  28  is outside of second operating range  18 , and cannot be detected by second master communication device  14 . Second master communication device  14  sends a second command signal  21  to first master communication device  12  with an indication that second wireless tracking device  24  was located, but fourth wireless tracking device  28  was not. An alarm is then activated on at least one of the first and second master communication devices  12 ,  14  to alert the user that a particular article, in this case laptop  29  associated with wireless tracking device  28 , is outside of the protective “force-field” and may have been lost or stolen.  
      System  10  then waits a predetermined time, such as 30 seconds, before repeating the scanning process looking for articles, although it should be understood that the duration of the waiting time can vary.  
      As shown, third wireless tracking device  26  is within both the first operating range  16  and the second operating range  18 . Optionally, second master communication device  14  may scan for and locate third wireless tracking device  26  and notify first master communication device  12  that third wireless tracking device  26  was located.  
       FIG. 2  shows first master communication device  12  inserted into a standard sized wallet  13 . First master communication device  12  is sized and shaped to be inserted into wallet  13  such that wallet  13  can be worn or carried by a user without difficulty. Typically, first master communication device  12  is about the same height and width dimensions as a credit card, while being somewhat thicker. It should be understood, however, that first master communication device  12  could be sized and shaped to fit other types of personal articles.  
      First master communication device  12  preferably comprises an alarm  30 , a small display screen  34 , and input keys  32 . Alarm  30  emits an audible tone of sufficient volume such that a user carrying wallet  13  would be able to hear the tone and be alerted to the fact that an article may have been lost or stolen. Alarm  30  could also vibrate or generate another signal notifying the user of an alarm condition. Input keys  32  may be used to program first master communication device  12 , to manually scan for a particular article, to deactivate the alarm  30  once the user has been alerted, to individually activate and deactivate master communications devices  12 ,  14  and each of wireless tracking devices  22 ,  24 ,  26  and  28 , and to perform other functions as required. Display  34  may provide the user with information about a particular alert, such as which wireless tracking device has gone missing, and which particular article that wireless tracking device was associated with. Display  34  may also be used to display information when programming first master communication device  12 , and other information as required.  
       FIG. 3  shows second master communication device  14  affixed to a set of keys  15 . Second master communication device  14  may be smaller than first master communication device  12 , and may comprise less features. For example, as shown second master communication device  14  comprises an alarm  36 , but no display screen or keys. It should be understood, however, that second master device  14  need not necessarily be subservient to first master device  12 .  
      The system of the invention could utilize a variety of different technologies for communicating between the master communications devices and the tracking devices. One such technology utilizes passive ID tags and a tag reader/interrogator. The operation of the tags uses transformer theory in the near magnetic field. A transformer has a primary winding and a secondary winding, and the ratio between the number of turns of the two windings gives the ratio between the primary and secondary voltages.  
      In one embodiment, the antenna of the reader/interrogator acts as the primary winding of the transformer while the tag antenna acts as the secondary. Signal strength at the tag is proportional to the cube of the distance from the reader. When the reader is turned on, the tag powers up and transmit its ID data. The binary pulses modify the impedance of the tag&#39;s antenna, which in turn causes an amplitude shift in the reader signal. The inductance of the antenna and the resonant capacitor form a resonant circuit tuned to the operating frequency of the system. The tag transmits data by tuning and detuning the resonant frequency of this circuit. This process loads and unloads the secondary winding to reflect an impedance back into the primary. The result is an AM wave with a very low percentage modulation. This signal is peak detected and reshaped into a serial data signal which will be read and validated by the controller/processor.  
      Passive tags receive the RF signal from the reader and they rectify and filter this signal to provide DC power for the circuitry. This approach limits the reading distance available. Active tags have their own power source (battery) to boost the transmit power back to the reader/interrogator so they have a longer read range.  
      Referring now to  FIG. 4 , illustrated therein is an embodiment of the system of the present invention in which the master communication devices  12 ,  14  comprise a wireless transceiver module  70  in the form of a tag reader/interrogator, and each of the wireless tracking devices comprise a passive ID tag  71 . Wireless transceiver module  70  is powered by a battery  72 , connected to a processor  74  that controls the operation of transceiver module  70 . Processor  74  may be a microcontroller or microprocessor. Transceiver module  70  further comprises an oscillator  76  for generating a time-varying signal, which is connected to a power amplifier  78  and then to an antenna  80 , for generating a wireless signal, such as commands signals  20 ,  21  or locating signals  31 ,  35  for communicating with wireless tracking devices  22 ,  24 ,  26 ,  28 . Antenna  80  is also connected to a peak detector  82  and to a resonating capacitor  84 . Peak detector  82  detects the peaks of incoming wireless signals  35 ,  37  and provides controller  74  with a more valid reading of values. Processor  74  includes a memory (not shown) as necessary as will be understood by those skilled in the art.  
      Passive ID tag  71  comprises a controller  86 , which may include a microcontroller or microprocessor, connected to a modulator  88  and a memory  94 . Memory  94  can be used to store information about RFID tag  71 , such as a unique identification number that is transmitted to transceiver module  70 . Modulator  88  is further connected to a rectifier/filter  92 , an antenna  90  and a resonating capacitor  96 . Rectifier/filter  92  is also connected to memory  94 .  
      During operation, when passive ID tag  71  is within the range of transceiver module  70  of first master communication device  12  or second master communication device  14 , passive ID tag  71  is powered by the electromagnetic field which is generated by the operation of antenna  80  of transceiver module  70 . The modulator  88  on the passive ID tag  22  modulates the incoming electromagnetic field in order to retrieve and transmit data to first transceiver module  70  using antenna  90 . Rectifier/filter  92  operates to transform the incoming electromagnetic field, which generates an AC current, into a DC current which is used to power modulator  88 , memory  94  and possibly controller  86 . Controller  86  passes data back and forth between memory  94  and modulator  88 .  
      Transceiver module  70  of master communication devices  12 ,  14  may be connected to input and output modules as desired, including but not limited to display screen  34 , input keys  32 , and alarm module  30 .  
      By using a passive ID tag  71 , wireless tracking devices  22 ,  24 ,  26 ,  28  can be made very small and lightweight, and there is no need to replace or recharge a separate power source.  
      Alternatively, wireless tracking devices  22 ,  24 ,  26 ,  28  could comprise active ID tags with an independent power source, instead of passive ID tags, which may be desirable when a larger operating range is preferred.  
      Referring now to  FIG. 5 , illustrated therein is a preferred embodiment of a method implemented by the system of the present invention.  
      At step  50 , a determination is made whether the first and second master communication devices  12 ,  14  are within a predetermined master range of each other. If first and second master communication devices  12 ,  14  are within the range, the system can proceed to step  52 . If first and second master communication devices  12 ,  14  are not within the range, the system proceeds to step  60 , and the system generates an alarm notifying the user that there is a problem.  
      At step  52 , the first master communication device looks for the presence of the first wireless tracking device  22  within a first operating range  16 . If first wireless tracking device  22  is located, the system then proceeds to step  54 . If first wireless tracking device  22  was not located, the system then proceeds to step  62 .  
      At step  62 , the second master communication device scans second operating range  18  for the presence of first wireless tracking device  22 . If first wireless tracking device  22  is located, the system proceeds on to step  54 . If second master communication device  14  does not locate first wireless tracking device  22 , the system proceeds to step  60  where an alarm is triggered, notifying the user that there is a problem and an article may have been lost or stolen.  
      At step  54 , first master communication device  12  scans to see if second wireless tracking device  24  is within its operating range  16 . If the second wireless tracking device  24  is located, the system proceeds to step  56 . If second wireless tracking device  24  is not located, the system proceeds to step  64 .  
      At step  64 , second master communication device  14  scans the second operating range  18  for the presence of second wireless tracking device  24 . If second wireless tracking device  24  is located, the system proceeds on to step  56 . If second master communication device  14  does not locate second wireless tracking device  24 , the system proceeds to step  60  where an alarm is triggered.  
      At step  56 , the first master communication device scans for third wireless tracking device  26  within its operating range  16 . If third wireless tracking device  26  is located within its range, the system then proceeds to step  58 . If third wireless tracking device  26  is not located, the system then proceeds to step  66 .  
      At step  66 , second master communication device  14  scans the second operating range for the presence of third wireless tracking device  26 . If third wireless tracking device  26  is located, the system proceeds on to step  58 . If second master communication device  14  does not locate third wireless tracking device  26 , the system proceeds to step  60  where an alarm is triggered.  
      At step  58 , first master communication device  12  scans for fourth wireless tracking device  28  within first operating range  16 . If fourth wireless tracking device  28  is located, the system the proceeds to step  70 . If fourth wireless tracking device  28  is not located, the system then proceeds to step  68 .  
      At step  68 , second master communication device  14  scans second operating range  18  for the presence of fourth wireless tracking device  28 . If fourth wireless tracking device  28  is located, the system proceeds on to step  70 . If second master communication device  14  does not locate the fourth wireless tracking device  28 , the system proceeds to step  60  where an alarm is triggered.  
      At step  70 , the system has successfully located all associated wireless tracking devices, and pauses for a predetermined time before repeating the scan. In a preferred embodiment, the predetermined time is 30 seconds.  
      Alternatively, first master communication device  12  could also scan for all wireless tracking devices within its range before instructing second master communication device  14  to scan for the wireless tracking devices that were not located by first master communication device  12 .  
      The system of the present invention provides a user with a portable, dynamic system for actively preventing the loss and theft of personal articles carried by the user, without requiring active user intervention. As such, the system provides the user with a personal “force-field” against the loss and theft of articles.  
      The system of the present invention has a number of advantages over the prior art systems. The two master communications devices of the present invention provide a double force field that has a greater range than that provided by prior art systems having a single master communications device. The subject system is also more versatile than prior art systems, in that the double force field of the present invention varies in strength as the person moves the two master communications devices relative to each other.  
      While the preferred embodiment utilizes two master wireless communication devices, the present invention could utilize a third master wireless communication device. Also, one or more of the wireless tracking devices affixed to personal articles could operate as a master communication device. It should also be apparent that the system of the present invention is not limited to any particular number of wireless tracking devices, and that the system could be set up to enable the user to add and dynamically activate additional wireless tracking devices.  
      The system of the present invention could also be modified to enable the master communication devices associated with different people to all work together to provide a wireless peer-to-peer communication network In this system, even if a particular article is lost or stolen and is not immediately recovered by the user, the user will be alerted when the particular article is detected by another “friendly” device.  
      Accordingly, while the invention has been described with regard to preferred embodiments, it should be understood by persons skilled in the art that various modifications may be made thereto without departing from the present invention, the scope of which is defined in the claims appended hereto.