Abstract:
A security device and alarm system includes a reader preferably concealed in a fabric article, at least one tag, and an alarm unit. The reader includes a reader transmitter, reader receiver, CPU, power source, and power switch. The tag includes a tag transmitter and a tag receiver. If using active RFID tags, each tag includes a power source. The alarm unit includes an alarm receiver, alarm, and power source. If the reader receiver does not receive an appropriate reply from the tag transmitter after the reader transmitter sends a query to the tag receiver, or if the reader was deactivated, the reader transmitter sends an alarm signal to the alarm unit. Upon the alarm receiver&#39;s receipt of the alarm signal, the alarm is energized. If using multiple active RFID tags, the CPU checks for each through tag transmission identifiers, and the alarm identifies the missing tag through unique alarm signals.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to a security device. In particular, the present invention relates to an anti-theft security device and alarm system. 
   Security devices are a part of doing business today. The low cost and obvious benefit of anti-theft measures make them used even on objects of small value in department and retail stores. However, rare objects and collectibles are often found unprotected in today&#39;s marketplace. This is partly the result of the decentralized nature of the antique business, trade shows, festivals, and similarly operated businesses in which there are many operators of independent booths in a single area. An anti-theft measure addressing the needs of decentralized merchants would be a welcome addition to their professions. Specifically, an alarm system is needed that provides warning when a dealer&#39;s property is moved. 
   Many stores utilize AM (acousto-magnetic) tags. Wide entrances can be covered, and the tags themselves are inexpensive. A transmitter is set near the area to be monitored (usually on one side of the store&#39;s door) and sends out intermittent pulses of radio waves. The material the tag is made of actually expands and contracts in size in the presence of this radio field. If the transmitter is operating at the correct frequency, the tag resonates like a tuning fork and produces a radiated signal that continues in between the pulses of radio waves. A receiver set to correspond to the transmitter (usually on the opposite side of the store&#39;s door, so that everything must pass between the transmitter and receiver when leaving) listens for this vibration to sense a tag. This system cannot distinguish multiple tags, however, and is poorly suited for monitoring multiple booths or areas without tightly controlled exits. 
   The most commonly used anti-theft systems in stores are swept-RF systems, mostly due to their extremely low cost. In these systems, a tag is little more than a simple transmitter circuit and a flexible aluminum antennae printed on a paper backing. When an item is purchased, a high-energy burst of radio energy is delivered in close proximity to the tag. This burns out the circuitry and deactivates the tag. Receivers are positioned at the stores&#39; exits to detect active tags. However, like the AM systems described above, swept-RF is unable to distinguish multiple tags. It also suffers from being poorly suited for monitoring multiple booths or areas without tightly controlled exits. 
   The fastest rising trend in security products is RFID (Radio Frequency Identification). Essentially, a stationary reader sends out a radio signal of a particular frequency. The tag responds to this signal by “replying” in a way that alerts the reader that a tag has just entered its range. This information can then be used to draw conclusions about the location of the tagged object. If a theft is suspected, an alarm can be triggered. In passive RFID systems, the tag does not require a battery. Instead, the energy of the reader signal provides the energy necessary to reply. The circuitry required is exceedingly small—not much bigger than a grain of rice. These devices can also be very unobtrusive and have lengthy life-spans. The largest disadvantage of passive systems is that the reader must provide a powerful transmission in order to power the tag. This results in large power requirements and limits the signal range. Generally the tag must be within a few feet of the reader to be “seen”. 
   Active RFID systems are powered by a battery onboard the tag. When the tag detects the reader signal, it transmits a reply. Some active systems have a range of hundreds of feet, but more importantly multiple tags can be identified simultaneously. The tag can also respond independently of the reader, such as activating if an attempt is made to disable it. Both passive and active RFID systems in the current state of the art rely on detecting the presence of a tag near an exit to activate an alarm. 
   Various proposals for other theft alarm devices are found in the art. U.S. Pat. No. 4,584,571 discloses attaching a permanent magnetic body to a valuable article that is placed in a bag. The bag includes circuitry that sets off an alarm when the magnet is missing unless manually overridden. 
   U.S. Pat. No. 5,963,131 discloses using a motion sensor in combination with a proximity sensor to guard valuables and reduce incidences of false alarms. A theft detector unit is integrated into a laptop, and a control unit is carried by the user to maintain two-way communication with the laptop. 
   U.S. Pat. No. 6,172,607 discloses an alarm that is attached to an object and manually activated. When the object is thereafter moved, an alarm sounds until disarmed by entering a security code or the internal power source is exhausted. Thus, the alarm detects its own movement, and no corresponding device is used. 
   While assumably effective for their intended purposes, none of the above proposals provide an anti-theft alarm system that addresses the needs of decentralized merchants. Therefore, it is desirable to have a security device and alarm system that is unobtrusive, can be used in a variety of settings, is able to monitor and distinguish between multiple objects, alerts the merchant when the device is turned off, and is inexpensive. 
   SUMMARY OF THE INVENTION 
   A security device and alarm system according to the present invention includes a reader, at least one security tag, and an alarm unit. The reader includes a reader transmitter, a reader receiver, a CPU, a reader power source, and a power switch. The security tag is remote from the reader and includes a tag transmitter electrically connected to a tag receiver. If active RFID tags are used, each tag also includes a power source. The alarm unit is remote from the reader and the tag and includes an alarm receiver and an alarm electrically connected to an alarm power source. 
   In use, an inspection loop is established wherein the reader transmitter sends a query signal to the tag, the tag receiver receives the query signal, the tag transmitter sends a reply signal, the reader receiver receives the reply signal, and the reader CPU checks for the appropriate reply signal and for power failure of the reader. If an appropriate reply signal is not received by the reader receiver or if the CPU has been turned off, the reader transmitter sends an alarm signal to the alarm unit. Upon receipt of an alarm signal by the alarm receiver, the alarm is energized. If multiple active RFID tags are used, the reader CPU checks for the presence of each active RFID tag through the use of tag transmission identifiers. Further, unique alarm signals are used to identify the missing active RFID tag, and the alarm includes means to identify each active RFID tag individually. The reader is preferably concealed in a fabric article, though other arrangements are of course possible. 
   Therefore, a general object of this invention is to provide a security device and alarm system that takes into account the decentralized nature of many businesses. 
   Another object of this invention is to provide a security device and alarm system, as aforesaid, that is unobtrusive. 
   Still another object of this invention is to provide a security device and alarm system, as aforesaid, that can be used in a variety of conditions, such as inside, outside, in separate booth arrangements, in large galleries, etc. 
   Yet another object of this invention is to provide a security device and alarm system, as aforesaid, that is able to monitor and distinguish between multiple objects. 
   A further object of this invention is to provide a security device and alarm system, as aforesaid, that alerts the merchant when the device is turned off. 
   A still further object of this invention is to provide a security device and alarm system, as aforesaid, that is inexpensive. 
   Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, embodiments of this invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a security device and alarm system according to one embodiment of the present invention with the reader being positioned in a fabric article, the tag being incorporated into a vase, and the alarm unit; 
       FIG. 2  is a block diagram showing the components of the security device and alarm system as in  FIG. 1 ; 
       FIG. 3  is a flow chart explaining the operation of the security device and alarm system as in  FIG. 1 ; 
       FIG. 4  is a top view of a reader according to another embodiment of the present invention being positioned in a fabric article, but shown without the fabric, and an alarm unit according to another embodiment of the present invention, but shown without tag devices; 
       FIG. 5  is a block diagram showing the components of the security device and alarm system as in  FIG. 4 ; 
       FIG. 6  is a flow chart explaining the operation of the security device and alarm system as in  FIG. 4 ; 
       FIG. 7  is a perspective view of a security device and alarm system according to still another embodiment of the present invention, but shown without an alarm unit; 
       FIG. 8   a  is a perspective view of the security device and alarm system as in  FIG. 7 ; and 
       FIG. 8   b  is a perspective view of the security device and alarm system as in  FIG. 7 , but shown without tag devices or the case lining. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   A security device and alarm system according to the present invention will now be described in detail with reference to  FIGS. 1 through 3  of the accompanying drawings. More particularly, a security device and alarm system  100  includes a reader  110 , a security tag  120 , and an alarm unit  130 . 
   The reader  110  includes a reader transmitter  112 , a reader receiver  114 , a CPU  116 , a reader power source  118 , and a power switch  119  electrically connected as shown in  FIG. 2 . The reader transmitter  112  is capable of transmitting query signals  150  and alarm signals  152 , and the reader receiver  114  is capable of receiving reply signals  154 . The reader transmitter  112  and the reader receiver  114  preferably utilize RFID (Radio Frequency Identification) technology, making the reader  110  a RFID reader  110 . A wire loop antenna  113  preferably functions as both the reader transmitter  112  and the reader receiver  114 , though other transmitters and receivers may of course be used. It is also understood that other technologies may be suitable besides RFID, such as AM (acousto-magnetic) or swept-RF technology. 
   The tag  120  is remote from the reader  110  and includes a tag transmitter  122  electrically connected to a tag receiver  124  ( FIG. 2 ). The tag transmitter  122  is used to transmit reply signals  154 , and the tag receiver  124  is used to receive query signals  150 . Here, the tag  120  is a passive RFID tag and does not require a battery power source. Instead, energy from signals received by the tag receiver  124  is used to power the tag transmitter  122 . Whenever the tag receiver  124  receives a query signal  150 , the energy from the query signal  150  powers the tag transmitter  122 , and the tag transmitter  122  transmits a reply signal  154 . 
   The alarm unit  130  is remote from the reader  110  and the tag  120  and includes an alarm  132 , an alarm receiver  134 , and an alarm power source  138  electrically connected as shown in  FIG. 2 . The alarm receiver  134  is used for receiving alarm signals  152 , and the alarm  132  is used to notify a user of the alarm signal  152 . Whenever the alarm receiver  134  receives an alarm signal  152 , the alarm power source  138  energizes the alarm  132 . The alarm  132  may incorporate various alarming devices, such as a piezoelectric buzzer  135 , a vibrator  136 , or a visual alarm  137 , or the like ( FIG. 4 ). The alarm unit  130  may be very small, allowing the alarm unit  130  to be shaped like jewelry (such as the bumblebee broach alarm unit  133  seen in  FIG. 1 ) or to be placed easily in a pocket. Conversely, the alarm unit  130  may be larger to incorporate a piezoelectric buzzer  135 , a vibrator  136 , and a visual alarm  137 , as well as other desired alarming devices ( FIG. 4 ). Ideally, the alarm  132  unobtrusively informs the user that an object has been moved from the range of the security device and alarm system  100 . 
   In use, the reader  110  is preferably positioned in a fabric article for concealing the presence of the reader  110 , such as a table with a fabric top  3  ( FIG. 1 ), a tablecloth, or rug. While most large retailers with tightly controlled exits opt to make their security devices clearly visible, it may be beneficial to the decentralized merchant to conceal the presence of the security device and alarm system  100 . Concealment that a security system exists may in fact reduce the likelihood that someone will attempt to bypass the security device and alarm system  100  while unattended. The tag  120  is attached to an item of value that the user wishes to protect by adhesives, clips, or other attachment means. The tag  120  is shown attached to a vase  2  in  FIG. 1 . The user then monitors the alarm unit  130 . The processing steps of the logic performed by the reader  110  are shown in the flowchart of  FIG. 3 . 
   In process step S 1 , the reader power switch  119  is pressed, turning the reader  110  on. The process then proceeds to step S 2 , where the reader transmitter  112  sends a query signal  150  to the tag receiver  124 . The process then proceeds to step S 3 , where the reader receiver  114  attempts to receive a reply signal  154  from the tag transmitter  122 . The process then proceeds to step S 4 . 
   In process step S 4 , the reader CPU  116  determines whether the reader receiver  114  received a reply signal  154  from the tag transmitter  122 . If so, the process is directed to step S 6 . If not, the process is directed to step S 5 . 
   In process step S 5 , the reader transmitter  112  sends an alarm signal  152  to the alarm receiver  134 , and the process proceeds to step S 6 . It should be appreciated that the reader  110  is using an object&#39;s absence to notify a user of possible theft, unlike traditional anti-theft devices used by large retailers that use an object&#39;s presence near an exit to notify of possible theft. 
   In process step S 6 , the reader CPU  116  determines whether the reader power switch  119  has been pressed to turn the reader  110  off. If not, the process proceeds to step S 2 , forming an inspection loop. If so, the process is directed to step S 7 . 
   In process step S 7 , the reader transmitter  112  sends an alarm signal  152  to the alarm receiver  134 , and the process proceeds to step S 8 . 
   In process step S 8 , the reader  110  deactivates (turns off). It is obvious, then, that the reader  110  cannot be deactivated without the user being warned. 
   A security device and alarm system  200  according to another embodiment of the present invention is shown in  FIGS. 4 through 6  and includes a construction substantially similar to the construction previously described except as specifically noted below. More particularly, the security device and alarm system  200  according to this embodiment is an active RFID system. 
   Each tag  120  of a plurality of tags  120  is an active RFID tag that includes a tag transmitter  122 , a tag receiver  124 , and a power source  228  ( FIG. 5 ). Each tag transmitter  122  has a predetermined tag transmission identifier  254  different from a predetermined tag transmission identifier  254  of any other tag transmitter  122  ( FIG. 5 ). Whenever the tag receiver  124  receives a query signal  150 , the power source  228  powers the tag transmitter  122 , and the tag transmitter  122  transmits a reply signal  154  that includes a corresponding tag transmission identifier  254 . The tag transmission identifier  254  is preferably a unique modulation or frequency, though other identifiers are of course possible. 
   The reader transmitter  112  and the reader receiver  114  utilize active RFID technology, making the reader  110  an active RFID reader  110  ( FIG. 5 ). The reader CPU  116  has means for recognizing each tag transmission identifier  254  and associating each tag transmission identifier  254  with a corresponding active RFID tag  120 . The reader CPU  116  also has means for determining whether an appropriate reply signal  154  is received by the reader receiver  114  after the reader transmitter  112  transmits a corresponding query signal  150 . The reader transmitter  112  includes means for transmitting a plurality of unique alarm signals  252 , and each unique alarm signal  252  is associated with a respective active RFID tag  120 . Transmission of the unique alarm signals  252  by the reader transmitter  112  is actuated by the reader CPU  116  if the appropriate reply signals  154  are not received by the reader receiver  114  after the reader transmitter  112  transmits a corresponding query signal  150 . 
   The alarm unit  130  includes means for indicating which active RFID tag  120  is associated with each unique alarm signal  252  and, when the alarm receiver  134  receives a unique alarm signal  252 , the alarm  132  indicates the associated active RFID tag  120 . This may be done through a plurality of visual alarms  137 , different behaviors of the piezoelectric buzzer  135  or the vibrator  136 , or a combination of the various alarming devices. 
   The processing steps of the logic performed by the reader  110  are shown in the flowchart of  FIG. 6 . In process step S 201 , the reader power switch  119  is pressed, turning the reader  110  on. The process then proceeds to step S 202 , where the reader transmitter  112  sends a query signal  150  to the tag receivers  124 . The process then proceeds to step S 203 , where the reader receiver  114  receives all reply signals  154  and the reader CPU  116  records the corresponding tag transmission identifiers  254 . The process then proceeds to step S 204 . 
   In process step S 204 , the reader transmitter  112  sends a query signal  150  to the tag receivers  124 . The process then proceeds to step S 205 , where the reader receiver  114  receives all reply signals  154 . The process then proceeds to step S 206 . 
   In process step S 206 , the reader CPU compares each tag transmission identifier  254  received in step S 205  to the tag transmission identifiers  254  recorded in step S 203  and determines if any replies are missing. If so, the process is directed to step S 207 . If not, the process is directed to step S 208 . 
   In process step S 207 , the reader transmitter  112  sends a unique alarm signal  252  corresponding to the missing active RFID tag  120  to the alarm receiver  134 , and the process proceeds to step S 208 . 
   In process step S 208 , the reader CPU  116  determines whether the reader power switch  119  has been pressed to turn the reader  110  off. If not, the process proceeds to step S 204 , forming an inspection loop. If so, the process is directed to step S 209 . 
   In process step S 209 , the reader transmitter  112  sends a unique alarm signal  252  corresponding to the power failure to the alarm receiver  134 , and the process proceeds to step S 210 . 
   In process step S 210 , the reader  110  deactivates (turns off). It is obvious, then, that the reader  110  cannot be deactivated without the user being warned and that the user receives notice of which RFID tag  120  is missing, if any. 
   A security device and alarm system  300  according to still another embodiment of the present invention is shown in  FIGS. 7 through 8   b  and includes a construction substantially similar to the construction previously described except as specifically noted below. More particularly, the reader  110  of the security device and alarm system  300  according to this embodiment is positioned in an ornamental case  4  for concealing the presence of the reader  110 .  FIG. 8   b  is shown without the case lining  5  to better demonstrate the security device and alarm system  300 . 
   It is understood that while certain forms of this invention have been illustrated and described, it is not limited thereto except insofar as such limitations are included in the following claims and allowable functional equivalents thereof.