Abstract:
A system for remote detection using and RFID system including a transceiver, a transponder and a fuse configured within the transponder. The transceiver is configured to send and receive radio frequency signals. The transponder is configured to receive radio frequency signals from the transceiver and to send radio frequency signals to the transceiver. The transceiver is configured to send radio frequency to the transponder thereby preventing the fuse from blowing while the radio frequency signal is received.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This Utility Patent Application is related to U.S. patent application Ser. No. 11/117,803, entitled “REMOTE MEASUREMENT EMPLOYING RFID,” and U.S. patent application Ser. No. 11/117,994, entitled “REMOTE MEASUREMENT OF MOTION EMPLOYING RFID,” which are all filed on even date herewith, are all assigned to the same assignee as the present application, and are all herein incorporated by reference. 
   BACKGROUND 
   The present invention relates to radio frequency (RF) communications, and more particularly, to radio frequency identification (RFID) systems. Wireless communication systems that communicate signals over the RF spectrum are well known in the art. One such system is the RFID system. Typically, an RFID system includes a transceiver having a transceiver antenna, and a tag or transponder having a transponder antenna. Typically, the transponder is electronically programmed with unique information. The transceiver periodically transmits RF interrogation signals to the transponder. Upon receiving an interrogation signal, the transponder responds by transmitting a response signal containing data. 
   RFID systems have been used in a variety of circumstances, such as for tracking inventory, tracking movements of objects, various security applications, and a variety of other applications. RFID systems have not, however, typically been employed in remote enabling devices. Consequently, there is a need for the present invention. 
   SUMMARY 
   One aspect of the present invention provides a remote detection system. The system includes a transceiver and a transponder. The transceiver is configured to send and receive radio frequency signals. The transponder is configured to receive radio frequency signals from the transceiver and to send radio frequency signals to the transceiver. The transponder also includes a fuse. The transceiver is configured to send radio frequency to the transponder thereby preventing the fuse from blowing while the radio frequency signal is received. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block/schematic diagram illustrating an RFID system. 
       FIG. 2  is a block diagram illustrating a transponder. 
       FIG. 3  is a block diagram illustrating a transponder in accordance with one embodiment of the present invention. 
       FIG. 4  is a block/schematic diagram illustrating an RFID system in accordance with one embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention can be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments can be utilized and structural or logical changes can be made without departing from the scope of the present invention. The following Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
     FIG. 1  illustrates radio frequency identification (RFID) system  10 . RFID system  10  includes transceiver  12  and transponder  20 . Transceiver  12  includes transceiver antenna  14 . Transponder  20  includes transponder antenna  22 . Signals generated by transceiver antenna  14  and by transponder antenna  22  are transferred through medium interface  16 . 
   Transceiver  12  of RFID system  10  is configured to communicate with transponder  20 . In one embodiment, transceiver  12  includes a microprocessor, and in another embodiment, transceiver  12  is coupled to a host system that includes a microprocessor. In one embodiment, transceiver antenna  14  is integrated within a single transceiver device. In one embodiment, transceiver  12  includes a separate transceiver circuit device and a separate transceiver antenna  14 . Transceiver antenna  14  emits radio frequency signals that are transmitted through medium  16  to activate transponder  20 . After activating transponder  20 , transceiver  12  reads and writes data to and from transponder  20 . Transceiver antenna  14  and transponder antenna  22  are the conduits between transceiver  12  and transponder  20 , and communicate radio frequency signals through medium interface  16 . 
   In some embodiments, medium interface  16  is air, and in other embodiments medium interface  16  includes air and other materials. Transceiver antenna  14  and transponder antenna  22  can be of a variety of shapes and sizes, dependent upon the anticipated distance separating them, the type of medium  16  that is between antennas  14  and  22 , and on other factors. 
   Transceiver  12  typically performs a variety of functions in controlling communication with transponder  20 . In one case, transceiver  12  emits output signals from transceiver antenna  14 , thereby establishing an electromagnetic zone for some distance adjacent antenna  14 . When transponder  20  passes through the electromagnetic zone established by transceiver antenna  14 , transponder  20  detects an activation signal from transceiver  12 . Transponder  20  typically has integrated circuits that include data that is encoded in memory. Once transponder  20  is activated with the activation signal, transceiver  12  decodes data that is encoded in transponder  20 . For instance, in one embodiment transceiver  12  performs signal conditioning, parity error checking and correction. 
   Typically, transceiver  12  emits radio waves in ranges from a few millimeters up to hundreds of feet or more, depending on its output power and upon the radio frequency used. In one case, transceiver  12  is integrated in a circuit board card that is then coupled to a host computer, which processes the received data and controls some of the communication with transponder  20 . 
     FIG. 2  illustrates one embodiment of transponder  20 . In one embodiment, transponder  20  includes transponder antenna  22 , analog circuitry  24 , digital circuitry  26 , and memory  28 . In various embodiments, memory  28  can include read only memory (ROM)  30 , flash memory  32 , and/or random access memory (RAM)  34 . 
   Transponder  20  comes in a variety of shapes and sizes for use in a variety of applications. For example, in one embodiment transponder  20  is configured as a small cylindrical-shaped tube having a diameter the size of a typical pencil lead. For example, such a transponder can be inserted beneath the skin of an animal to facilitate tracking the animal. In another embodiment, transponder  20  is screw-shaped such that it is screwed into trees or wooden items for identification or related purposes. In still other cases, transponder  20  is credit-card shaped for use in a multitude of access and/or security applications. In another embodiment, transponder  20  is embedded in hard plastic tags attached to merchandise in stores for security purposes, and in other embodiments it is in heavy-duty relatively large cases that are used to track inter-modal containers or heavy machinery, as well as a variety of other applications. 
   In some embodiments, transponder  20  includes one or more types of memory  28 . For example, in some embodiments memory  28  includes ROM  30  to accommodate security data and operating system instructions that are employed in conjunction with analog circuitry  24  and digital circuitry  26  to control the flow of data within transponder  20 . In other embodiments, memory  28  includes RAM  34  to facilitate temporary data storage during a time period when transceiver  12  is interrogating transponder  20  for a response. In other embodiments, memory  28  includes flash memory  32  to store data in transponder  20  that is non-volatile in order to ensure that the data is retained when transponder  20  is in a quiescent or power saving state. In some embodiments, memory  28  includes other types of non-volatile programmable memory, such as programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), and electrically erasable programmable read-only memory (EEPROM). Any one of memory types ROM  30 , flash memory  32  (or other non-volatile programmable memory), or RAM  34  can be used, or any combination thereof can be used. 
   In one embodiment, transponder  20  is an active transponder device. An active transponder is powered by an internal energy source, such as a battery configured within analog circuitry  24 . Such active transponders are typically “read/write,” which means data stored within memory  28  of transponder  20  can be rewritten and/or modified. An active transponder can also be powered from an existing source in another electronic device. For example, where transponder  20  is an active transponder coupled within a computer system, the power supply within the computer system supplies power to the transponder. 
   In one embodiment, transponder  20  is a passive transponder device. Passive transponders operate without a separate internal power source and obtain operating power from transceiver  12 . Rather than having a battery within analog circuitry  24 , for example, passive tags instead can use a strongly capacitive circuit and a charge pump within analog circuitry  24 . The capacitive circuit and charge pump are configured to receive radio frequency energy from transceiver  12  and store it for use within transponder  20 , for example, to control digital circuit  26  and memory  28 . 
   Since active transponders accommodate an internal battery, they are typically larger in size than passive transponders. Memory size within an active transponder varies, but can be fairly significant with some systems operating, for example, with up to a megabyte or more of memory. Active transponders also typically have a longer ready range such that transceiver  12  and transponder  20  are typically placed apart at greater distances than in the case of passive transponders. In the same way, passive transponders typically have shorter read ranges, but are typically much smaller and lighter than active transponders and are typically less expensive. 
   In addition to including a battery for active transponders or capacitive circuit and charge pump for passive transponders, analog circuitry  24  typically include interface circuits for data transfer between transponder antenna  22  and digital circuitry  26 . Digital circuitry  26  in turn typically includes control logic, security logic, and internal logic or microprocessor capabilities. This control logic controls the flow of data to and from memory  28 . 
     FIG. 3  illustrates transponder  40  in accordance with one embodiment of the present invention. Transponder  40  includes transponder antenna  42 , analog circuitry  44 , digital circuitry  46 , read only memory (ROM)  50 , flash memory  52 , random access memory (RAM)  54 , and fuse  60 . In one embodiment, fuse  60  is configured to allow continued operation of transponder  40  when not blown. When fuse  60  is blown, however, transponder  40  becomes inoperable such that communication with transponder  40  with a transceiver is no longer possible. 
   In one embodiment, fuse  60  is configured to disable transponder  40  under certain conditions and allow it to function in other conditions. In operation, transponder  40  is used in conjunction with a transceiver such that a transceiver first sends radio frequency (RF) signals to transponder  40 . These RF signals are received via transponder antenna  42  and sent to analog circuitry  44 . In one embodiment, analog circuitry  44  includes a capacitive circuit and a charge pump. In this way, received RF signals charge the capacitive circuit within analog circuitry  44 . The storage energy is then used to energize digital circuitry  46 . 
   In one embodiment, digital circuitry  46  includes control circuitry for activating flash memory  52 , RAM  54 , and ROM  50  as well as fuse  60 . In this way, upon continued or periodic activation by digital circuitry  46 , fuse  60  stays enabled such that transponder  40  sends RF signals back to the transponder. In one embodiment, the transceiver then subsequently interrogates transponder  40  in order to read a digitized code stored in memory  48  of transponder  40 . When RF signals are no longer continually or periodically received by transponder  40  from the transceiver, however, fuse  60  will blow and disable transponder  40 . In this way, transponder  40  will no longer be able to send RF signals back to the transceiver. 
   In one embodiment, transponder  40  will no longer receive RF signals from the transceiver when transponder  40  is out of a set range of the transceiver. In this way, whenever the transponder  40  is out of this set range of the transceiver, fuse  60  will blow, thereby disabling transponder  40 . In one embodiment fuse  60  is an electronic fuse. 
     FIG. 4  illustrates RFID system  80  in accordance with one embodiment of the present invention. RFID system  80  includes computer system  81  having a transceiver  82 . Transceiver  82  has a transceiver antenna  84 , which can be embedded or external to transceiver  82 . RFID system  80  further includes first and second transponders  92  and  94 , which are coupled to first and second system components  96  and  98 , respectively. Medium interface  86  is between transceiver antenna  84  and first and second transponders  92  and  94 . 
   In one embodiment of the present invention, RFID system  80  is used in conjunction with assuring the security of computer system  81 . In the way, RFID system  80  detects whether first and second system components  96  and  98  have been removed from the proximity of computer system  81  by having transceiver  82  remotely detect the presence of transponders  92  and  94 . Because transponders  92  and  94  are fixed to first and second system components  96  and  98 , RFID system  80  determines that first and second system components  96  and  98  have been removed from the proximity of computer system  81  when transponders  92  and  94  are out of range of transceiver  82 . Thus, RFID system  80  disables computer system  81  when transponders  92  and  94  are out of range of transceiver  82 . 
   In one embodiment, RFID system  80  utilizes first and second transponders  92  and  94  and transceiver  82 , which is embedded in an electronic module such as computer system  81 . Transceiver  82  is configured to scan the proximity of medium interface  86  specifically for first and second transponders  92  and  94 . In one embodiment, transponders  92  and  94  are configured like transponder  40  in  FIG. 3 , such that each has a memory and a fuse. A unique identification code is stored in each memory of transponders  92  and  94 . If transceiver  82  scans and receives the unique code from each of transponders  92  and  94 , then computer system  81  is allowed to function normally. If transceiver  82  scans and does not receive the unique code from each of transponders  92  and  94 , however, then the fuse (or several fuse links in some embodiments) is blown. 
   In one embodiment, computer system  81  further includes an embedded-security device such as a Trusted Platform Module (TPM). TPM is known to those skilled in the art as a means for authenticating internal and external communications to a computer or computer system by using an encrypted digital signature. TPMs typically provide authentication of components of computing systems that are not transferable from system to system. In other words, the security of a computing system can be compromised if the TPM is moved from one system to another. In one embodiment, each of first and second system components  96  and  98  are TPMs. In this way, corresponding transponders  92  and  94  are embedded in TPMs  96  and  98 . In one embodiment, TPMs  96  and  98  are physically connected within computer system  81  and in another embodiment TPMs  96  and  98  are coupled externally to computer system  81 . 
   Thus, with one embodiment of RFID system  80 , TPMs  96  and  98 , along with embedded transponders  92  and  92 , can be physically disconnected from computer system  81  without sacrificing or compromising the security of the system, as long as the modules are not moved out of the range established between transceiver  82  and its associated transponders  92  and  94 . Thus, for example, TPMs can be removed from computer system  81  to allow repair, as long as the TPMs and embedded transponders  92  and  92  stay within range of associated transceiver  82 . RFID system  80  only blows fuses within transponders  92  and  94  embedded in TPMs  96  and  98  when TPMs  96  and  98  are powered on and far enough away from away from transceiver  82 . Transceiver  82  is essentially “keyed” to transponders  92  and  94  in that it sends RF signals to transponders  92  and  94  in order to receive back the unique code stored therein. If the code is not received, the fuses are blown and the TPM is disabled. In this way, RFID system  80  provides security of computer system  81  with an embedded TPM. 
   In one embodiment, transponders  92  and  94  each contain a one-time programmable number in their respective memories. Transceiver  82  then sends RF signals to the transponders, and receives the one-time programmable number when transponders  92  and  94  are in range to verify a match. Thus, the transceiver  82  will only check for a match if it has been programmed with the value of transponders  92  and  94 . 
   In one embodiment, the transponders  92  and  94  are transponder types that are typically attached to the system in a label, or are physically embedded in the computer system. This provides added security benefit. In this way, if the TPM with embedded transponder is removed and placed in a computer system without the matching transceiver, the TPM will be made permanently inoperable. Since, the TPM is typically tied to a particular computer system of a particular system manufacturer, RFID system  80  appropriately destroys or disables the TPM that has been removed from the proper system. At the same time, however, RFID system  80  still allows legitimate repair of a system, where the TPM has to be removed, but not moved out of the proximity of the corresponding transceiver. 
   In one embodiment, RF signals received from transceiver  82  are received by the associated transponder antenna within first and second transponders  92  and  94 , and sent to analog circuitry, which in one case includes a capacitive circuit and charge pump. Energy stored in the capacitive circuit is then used to control digital circuitry within each of first and second transponders  92  and  94 . When first and second transponders  92  stop receiving RF signals, the digital circuitry is configured to activate or blow the fuse such as the transponders become disabled. In this embodiment, continued RF signal from transceiver  82  is needed to continue enabling the fuses and the transponders. 
   In one embodiment, RFID system  80  includes first and second transponders  92  and  94 , which are active transponders. In this embodiment, first and second transponders  92  and  94  are configured such that each has a battery or similar energy storage device within the analog circuitry of each transponder. This provides an RFID system  80  with more flexible range, meaning that first and second transponders  92  and  94  are operable even when placed a further distance from transceiver  82 . 
   In one embodiment, RFID system  80  includes first and second transponders  92  and  94 , which are passive transponders. In one such embodiment, first and second transponders  92  and  94  are configured very similarly to transponder  40  illustrated in  FIG. 3 . In this way, a capacitive circuit and charge pump are provided within the analog circuitry of each of first and second transponders  92  and  94 . 
   In one embodiment of these passive first and second transponders  92  and  94 , each can also further include a charge building device. In this way, radio frequency signals received from transceiver  82  by first and second transponders  92  and  94  builds up additional charge over a period of time. This additional built-up charge can then be used to power the control circuitry within first and second transponders  92  and  94 . In this way, RF signals are sent by transceiver  82  to first and second transponders  92  and  94  over a first period of time. Subsequently, that charge is released and used to power control circuitry over a second period of time, which is a shorter period of time than the first. In this way, a relatively large signal is generated within each of first and second transponders  92  and  94  due to the quicker dispensing of that stored energy relative to how it was received. In one embodiment, the charge building device within passive first and second transponders  92  and  94  is a capacitive ladder, or similar circuitry for building and storing energy over time. 
   In an alternative embodiment of RFID system  80 , a transceiver is embedded within the TPM rather than the transponders. Furthermore, the transceiver is configured with a fuse, rather than the transponder. In this way, in operation of the alternative system the TPM with embedded transceiver can also be physically disconnected from computer system  81  without sacrificing or compromising the security of the system, as long as the modules are not moved out of the range established between the transceiver embedded in the module and its associated transponder. Thus, for example, the TPM can be removed from the computer system to allow repair, as long as the TPM and embedded transceiver stays within range of associated transponder. The alternative RFID system only blows fuses within the transceiver embedded in the TPM when the TPM is powered on and far enough away from away from transponder. In this way, the alternative RFID system provides security of the computer system with an embedded TPM. 
   In one embodiment, computer system  81  is a rack-level server implementation where first and second components  96  and  98  are individual servers. In another embodiment, computer system  81  is an individual server where first and second components  96  and  98  are integrated within computer system  81 . In this way, first and second components  96  and  98  are, for example, blade computers, disks, memory, I/O cards, or related components. 
   Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.